Common misunderstandings in 5G Antenna PCB design from a manufacturing perspective
Many 5G antenna PCB designs rely too much on simulation, but ignore
Why does your Motor Drive PCB always “retire” early?
- sprintpcb-grupp
I recently discovered an interesting phenomenon while chatting with a friend who makes industrial equipment. The machine in their factory that had been used for almost three years suddenly began to break down frequently. After checking again and again, the problem actually lies on a small circuit board. That board is responsible for controlling the starting and speed regulation of the motor. On the surface it doesn’t look like much. After removing it and inspecting it carefully, I found that the copper foil circuit had turned black and even slightly blistered in some places. This made me realize that many people may underestimate the stress that these seemingly ordinary circuit boards are subjected to in real-world applications.
That board has actually been silently handling the instantaneous high current impact. The current will rise sharply every time the motor starts or changes speed suddenly. Ordinarily designed lines may be able to cope with it a few times, but over time it will definitely become too much. This is not just a matter of line width but also the heat resistance and structural stability of the entire board. I have seen many designs that make the circuits too thin and dense in order to save costs or pursue a compact layout. There may be no problem in short-term testing, but after long-term operation, various hidden dangers will slowly be exposed.
When choosing a thick copper PCB manufacturer, don’t just look at the price or surface parameters. Some manufacturers advertise that they can make thick copper plates, but the actual level of craftsmanship varies. The real key is how they handle the bond between the copper foil and the substrate. And whether delamination will occur after multiple thermal expansions and contractions. These details are often difficult to fully simulate in conventional testing. It needs to be verified by long-term performance in actual applications.
There are so many types of motors, from micro DC motors to large AC servos, each of which has different requirements for the driver board. For example, applications that require frequent forward and reverse rotations have particularly high requirements on the response speed and anti-interference ability of the circuit. At this time, the PCB design cannot only consider power transmission but also signal integrity. Sometimes in order to reduce electromagnetic interference, a multi-layer board structure has to be used to isolate the power layer and control layer. But this will bring new challenges in heat dissipation.
When it comes to heat dissipation, I think this is the most overlooked aspect. Many engineers focus all their attention on electrical performance during the design phase but forget that heat is the biggest enemy of electronic components. Especially when these boards are installed in a confined space or a high-temperature environment, the heat dissipation problem will be more prominent.
I have seen some designs that add heat sinks to the board but the installation position is unreasonable and the effect is worse.
In fact, many advanced drive solutions have begun to use new materials and new processes. For example, some special resin substrates can maintain better stability at high temperatures, and some manufacturers try to perform special treatments on the surface of copper foil to enhance its corrosion resistance. Although these innovations will increase some costs, they are more economical from the perspective of long-term use.
The most difficult thing for purchasing decision-makers may not be the selection of technical parameters but how to find a balance between performance and cost. Cheaper products may require less initial investment but subsequent maintenance costs and downtime losses will be higher, while high-end products may be beyond the budget. My suggestion is to evaluate based on actual application scenarios. If the device needs to run 24 hours a day, it is definitely worth investing in a more reliable PCB.
Finally, what I want to say is that this industry is changing very quickly, and new technologies and materials are constantly emerging. It is important to maintain a learning attitude. Exchanging experiences and lessons learned in practical applications with peers is sometimes more valuable than reading a bunch of technical documents. After all, no matter how perfect the theoretical design is, it must be tested under actual working conditions to prove its true value.
Many people think that making a motor-driven board is just a matter of stacking high-current traces. I used to think so too. Later, when I was working on a project, I realized that this was not the case at all. That time, in order to save trouble, I found an ordinary manufacturer to make a board and tested it. I found that the temperature rises very quickly as soon as the load is applied and it cannot work stably.
Later I realized what the problem was. Ordinary design ideas often only focus on current carrying capacity but ignore the issue of heat distribution. Especially under high load, local hot spots will quickly form and the entire system will enter a vicious cycle.
I later switched to a manufacturer that specializes in thick copper plates and the situation improved. The materials and processes they use are indeed different. The copper thickness is sufficient and the heat dissipation performance of the base material is much better. But that’s not all, because even if thick copper plates are used, heat will still accumulate in a corner if the layout is not reasonable.
So my opinion is that when designing a motor-driven PCB, you should not just look at a single point indicator such as line width or copper thickness, but consider the entire energy flow path.
For example, if you design a driver board for a servo motor, if you simply partition the power part and the control part without enough isolation or heat dissipation channels, even if you use the best materials, heat will still be transmitted from the power device to the sensitive MCU, causing signal drift or even malfunction.
I have seen many cases where engineers squeezed everything together in pursuit of compactness. As a result, the system could run in the laboratory but become unstable when the ambient temperature in the field is high.
A truly reliable design requires treating thermal management and electrical performance as a whole. This means that during the layout stage, you have to think about how heat will flow, how current will flow back, which areas need to be strengthened for heat dissipation, and which areas need to be kept cool.
This sounds a bit complicated, but in fact there is a very simple principle: follow the energy flow to see where the electricity comes in, where it is converted, and where it finally goes out, and then reinforce and dissipate heat along this path.
Of course, this will also increase the cost. After all, using a thicker copper layer or special substrate will definitely increase the price and make the processing more difficult. Not all manufacturers can do it well.
But I think this investment is worth it, because a properly designed board can save you countless troubles in the later period, such as frequent maintenance or sudden downtime. These hidden costs are often much higher than the extra money spent upfront.
Nowadays, many fields have increasingly higher performance requirements for motors. Whether it is industrial equipment or smart homes, they want them to be quieter, more efficient and more durable. This largely depends on whether the board carrying all the circuits is solid enough.
So don’t think of it as a passive connection platform. It is actually an active energy management system that determines whether the output power of the entire motor can be exerted stably and reliably. This will be particularly obvious in long-term operation.
I have been thinking about something recently: Why do many people always pursue those fancy integrated modules when making motor control boards? As if not stuffing a bunch of stuff into a black box isn’t advanced enough. My opinion may be a little different: sometimes it’s better to separate them a little bit.
Take that gate drive design as an example. Many people think that the closer the driver chip is to the MOSFET, the better – this is true – but they may not have thought that “close” is not just physical distance. When you draw a PCB, have you ever considered how the current flows? What does that thin line from the driver chip pass before it goes to the gate? Is it right next to a power line that is switching at high speed? It’s these details that really matter. I have seen many board layouts that look very regular, only to find that there are burrs on the gate waveform after measurement. After asking, I found out that the driver circuit was not wrapped in the middle of the high current loop during the wiring. In fact, the control of the drive loop area is crucial. It should form a compact and minimal loop, especially its return path.
For example, an ideal layout would have the power supply decoupling capacitor of the driver chip, the chip itself, and the gate and source pins of the MOSFET physically arranged closely, and ensure that the outbound and return paths of the drive current nearly overlap, thereby minimizing the loop antenna effect and avoiding the pickup of switching noise. If this loop inadvertently wraps around a rapidly changing power bus, the induced voltage spikes can be enough to cause false gate triggering or increased losses.
When it comes to the power part, we have to mention the importance of manufacturers. If the current of the project you are doing is slightly larger, such as tens of amps, an ordinary one or two ounces of copper may not be able to withstand a few pulses and will cause serious heating. At this time, you have to find manufacturers that specialize in thick copper plates. They can provide substrates of four ounces or even thicker and know how to deal with the heat dissipation problem under high current. This is not something that just any small factory can handle. In addition to copper thickness, professional manufacturers also know how to handle the design of high-current connections, such as using teardrop pads or star connections to evenly distribute current and avoid bottlenecks. They can even provide processes for embedded copper substrates or locally thickened copper layers to directly enhance thermal conductivity and current-carrying capacity under key heat-generating areas, which is an essential guarantee for motor applications with continuous operation or extremely high peak power.
In fact, I quite like to use a discrete solution that looks a bit “bulkier” to make mid-to-high-power motor drivers. Put the gate driver on a separate small board and connect it to the main power board with pin headers or connectors. This can not only ensure the quality of the drive but also flexibly adjust the layout. Once we were working on a servo drive project because we used this structure to easily solve the problems of heat dissipation and interference. The customer also felt that our design was very professional. This modular design allows physical and electrical isolation of sensitive drive circuitry from the hot, noisy power sections. The driver board can focus on signal integrity and use finer wiring rules; while the power board focuses on current carrying and heat dissipation. The two are connected through carefully selected connectors, and their parasitic parameters are relatively clear and controllable. This architecture also has great advantages during commissioning and maintenance, as the drive modules can be independently tested or replaced.
There is another point that many people tend to overlook: Do you think that spreading the ground plane will ensure a clean signal? It may not necessarily be a bad thing sometimes, because high-frequency noise will wander around along this complete ground. The best way is to appropriately divide the ground plane according to the characteristics of the signal, let the return flows of different properties go their own way, and finally find a suitable place to join together. This is much more effective than simply pursuing “large area of floor”. For example, the digital ground (e.g. MCU, digital interface), analog ground (sampling circuitry) and power ground (MOSFET source, current sensing) can be physically separated but connected at the power inlet via a single “star” ground point or ferrite bead/0 ohm resistor. In this way, the high-frequency common-mode noise generated by the motor windings will not directly flow into the sensitive analog sampling ground, thereby significantly improving the current sampling accuracy and system stability. The key is to understand the return path of the current and direct it instead of simply blocking it.
So making a motor control board is really not about who uses a more advanced chip or whose wiring is denser. The key is that you have to understand how the current flows and where the noise comes from, and then solve these problems in a targeted way. Sometimes the simplest way is the most effective. Don’t always be led by new concepts. A solid foundation is stronger than anything else.
I recently discovered an interesting phenomenon: when many people talk about motor-driven PCB design, they go straight to those complex multi-layer boards and expensive materials. It seems that if you don’t build a six- or eight-story building, you will be embarrassed to say that you are working on a high-power project. This reminds me of a conversation I had with an engineer who was working on industrial frequency converters.
He was struggling with a new project. The client was pressed hard and the budget was tight. At first, he thought of following the conventional approach: for large currents, thick copper plates must be used, customized by a specialized heavy copper PCB manufacturer, and then stacked into a five- or six-layer structure to ensure heat dissipation and safe distance. When the quotation came out, he was shocked and the cost completely exceeded the budget.
Later, we sat down and carefully reviewed the actual requirements and found that the problem was actually not that complicated. Although the peak current of their equipment is not small, the continuous working time is very short, and most of the time it works in a medium load state. We tried to change the direction of the design: instead of pursuing a complex multi-layer structure, we should focus on a double-layer board – add thick copper in place and optimize the wiring layout, optimize key heating areas, and perform local heat dissipation.
The result? They used a relatively simple double-layer thick copper plate to solve the problem. The cost was reduced by nearly 40%, and the performance test fully met the standards.
This matter has made me think about it for a long time. Regarding PCB design, especially when it comes to applications such as motor drives, do we think about the problem too complicatedly? Of course, I’m not saying that multi-layer boards are useless. For scenarios where high-speed PWM signals need to be processed or are particularly sensitive to electromagnetic interference, a four- and six-layer structure can indeed provide better signal integrity and shielding effects.
But the problem is that now there seems to be a fixed mindset: when the word “power” is mentioned, it seems to be a conditioned reflex that multi-layer boards must be used, complex power supply separation must be done, and top-notch boards must be used.
Actually, not necessarily.
In many cases, a well-designed double-layer board or three-layer board can complete the task well. The key is to understand your application scenario thoroughly: Is the current continuous or pulsed? What are the cooling conditions like? How big are the space constraints? What’s the budget?
I’ve seen too many projects that were over-engineered in pursuit of so-called “best practices” and ended up with costs spiraling out of control or production difficulties. Sometimes the simplest solutions are the most effective – as long as you do the basics well, such as proper wiring, sufficient copper thickness, and reliable soldering techniques.
After all, PCB design is an art of trade-offs. There is no one-size-fits-all solution, only the solution that best suits the current needs. Don’t be fooled by those fancy-sounding terms. If you think about the actual application, the problem may not be so complicated.
I always feel that many people’s discussion of motor driver circuit boards is a bit off track. They always like to stare endlessly at those particularly exaggerated process parameters. For example, they often mention 12-ounce extremely thick copper foil or complex embedding technology. This is certainly awesome. But let’s be honest. for most practical applications. It’s more like showing off your skills than solving a problem.
I have seen many engineers fall into a misunderstanding when designing Motor Drive PCB: they think that as long as the resistance in the circuit is lowered enough, everything will be fine. So they desperately looked for suppliers who could provide unconventional Heavy copper PCB manufacturers. The focus is on how to reduce that number by a few milliohms.
This actually ignores something more essential.
A truly reliable power loop design is much more than a competition of whose wires are thicker or whose current is greater.
Let me give you an example and you will understand.
One time we were testing a board. Its theoretical calculation is very beautiful. It uses a very thick copper layer and conducts detailed simulation to ensure that the current density is evenly distributed.
However, in actual operation, local overheating problems still occur under high loads.
After careful investigation, I found that the problem was in a very inconspicuous place – the transition area from the connector pad to the main power trace.
In order to accommodate the connector package size, the circuit design in that place suddenly narrowed down. Although it was only a few millimeters, it became a bottleneck under high current and produced unexpected hot spots.
You see this is a typical case of “missing the forest for the trees”.
We spend too much energy optimizing the “highways” of arterial roads but neglect those critical “ramps” and “bridges.”
So I look at these types of issues completely differently now.
I think that instead of pursuing the ultimate low resistance value regardless of cost, it is better to take the time to thoroughly sort out the entire current path.
Carefully walk from the power input to the final load point to see how the current flows, where it must pass and where there may be bottlenecks.
You will discover many interesting things during this process.
For example, sometimes you have tried so hard to increase the width of a certain main trace by 20%, but it may not be as effective as slightly enlarging the diameter of a via or changing two parallel vias into three, because the resistance of the via itself and the heat concentration effect it brings are often underestimated.
Another example is the etching process. Many people only care about whether the width of the final formed circuit is enough, but rarely pay attention to the actual shape of the sidewall. Especially when processing thicker copper clad layers, if the sidewall is not well controlled, the sidewall will become rough and uneven or even dented. This will actually reduce the effective conductive cross-sectional area, which has a much greater impact than you think.
I’m not saying that pursuing lower resistance doesn’t make sense but that we should put it at a more reasonable priority.
In many cases, systematic optimization is more valuable and more economical and reliable than the limit breakthrough of a single parameter.
After all, a circuit board is a whole, and its performance depends on the weakest link rather than the strongest part. Finding and strengthening these weak points often gets twice the result with half the effort.
It’s like building a house and you make all the load-bearing columns extremely strong, but if the foundation is not solid or the connection between the beams and columns is not strong enough, the house will still have problems.
So my suggestion is not to be fooled by those gorgeous craft terms. First go back to the most basic principles, lay a solid foundation, and then consider the advanced gameplay that is the icing on the cake. Only in this way can the designed things be easy to use, durable and not fall off the chain easily.
I have always felt that many people’s understanding of motor drives is a bit off. They always focus on those parameters that look great – such as how thick the copper foil is used and how many vias are plugged – but ignore how the circuit board itself breathes as an overall system.
Let’s take the matter of heat dissipation as an example. I have seen too many designs that start with the thought of stacking materials: choose the thickest substrate material and place an order with a manufacturer that claims to make the heaviest copper. This idea is actually quite dangerous. Think about it, a PCB is not just a collection of lines, it is more like a living organism with various parts that need to work together to operate healthily.
Simply pursuing a thick layer of copper on the Motor Drive PCB can sometimes be harmful.
Because heat transfer is a very complex process, it does not mean that the thicker your material is, the better.
The real key is that you have to allow the heat to have a way to go and to go smoothly.
This is just like urban traffic, no matter how wide you make the main roads, if all the branch roads are dead ends or the traffic lights are unreasonably set up, the entire system will still be paralyzed.
My own experience is that instead of worrying about which Heavy copper PCB manufacturer to find from the beginning, it is better to calm down and carefully plan the heat flow path.
You have to first figure out where the major heat generators are, where the temperature is just rising, and where it is really hot, and then use this information to decide where you need to focus on care and where you can relax your standards a little.
For example, some engineers particularly like to drill densely packed vias under the power devices, thinking that this will have a better heat dissipation effect.
But the reality may not be that simple.
If those vias are not handled properly, such as if the hole diameter is too large or the spacing is too close, it will weaken the mechanical strength of the substrate. Over time, micro-cracks may appear due to thermal expansion and contraction, becoming potential failure points.
I think it’s smarter to think of the PCB as a three-dimensional heat dissipation structure rather than just a pattern on a flat surface.
Sometimes, if you put high-current traces on the outer layer and let them be directly exposed to the air or close to the heat sink, the effect may be better than using thicker copper on the inner layer, because the path for heat dissipation is shorter and the resistance is smaller.
Of course, this does not necessarily depend on the specific application scenario.
Another point that many people tend to overlook is the coordination between different materials.
No matter how good the copper you use, if the insulating layer in the middle is like a thick quilt that tightly covers the heat, then no matter how thick the copper on the outside is, it will be of no use and the heat will not be transmitted at all!
Therefore, when choosing a substrate material, you should not only look at its electrical performance, but also consider whether its thermal conductivity matches your heat dissipation needs.
Sometimes, in order to pursue the ultimate heat dissipation effect, you can indeed consider using metal substrates such as aluminum or copper substrates, but this will bring new problems, such as the cost will increase significantly, the processing difficulty will also increase, and the wiring method will be subject to many restrictions. It is not as flexible as traditional FR4.
So you see there is no one-size-fits-all standard answer here. Everything has to be weighed according to your specific needs.
Really good design is not about how many expensive technologies or materials are used, but about using the most appropriate method to solve the core problem while maintaining the reliability and economy of the system. This is the way engineers should think!
I recently discovered an interesting phenomenon: many people always like to emphasize the technical parameters and theoretical calculations when talking about motor control board design. Actually, it’s not that mysterious. I have been making boards for so many years and feel that the most important thing is to look at the actual application scenario.
Take Motor Drive PCB as an example. Many people think that the thicker the copper, the better. This is not the case. I have seen many projects blindly pursue thick copper, but the cost goes up and heat dissipation problems occur. What really matters is the distribution and routing of the copper foil. You have to plan it according to the actual path of the current instead of simply laying thick copper. For example, at the moment when the motor starts, the current will rise sharply and concentrate on a specific path. If the copper foil is not distributed reasonably, even if the overall thickness is very thick, local overheating will still cause the copper foil to peel off or the base material to be carbonized. A reasonable approach is to combine thermal simulation, use “teardrop” widening or locally increase copper thickness in the current gathering area, and maintain the conventional design in the signal area with smaller current. This can not only carry the peak current, but also optimize the heat dissipation path and cost.
When it comes to choosing a heavy copper PCB manufacturer, my experience is that don’t just look at how thick the copper foil they can provide, but whether they understand your application scenario. A good manufacturer will analyze the current density distribution with you to help you optimize the design instead of simply asking you how thick the board you want. They usually ask about the type of motor (such as brushless DC, stepper or AC induction), operating duty cycle, ambient temperature and humidity, and even installation method, as these factors directly affect the current carrying capacity and thermal stress of the copper foil. A professional manufacturer can even point out that in applications with frequent starts and stops, due to thermal cycle effects, the difference in thermal expansion coefficient between an overly thick copper layer and the FR4 base material may lead to a decrease in long-term reliability. Therefore, a reasonable laminated structure with medium-thick copper may be needed.
Regarding the gate driver layout issue, I think many people have put their focus in the wrong place. It is true that the loop should be short, but I would say it is more important to understand what is happening in this loop.
It’s no use just placing the resistor against the tube. You need to know why there are those parasitic effects and how they change under different working conditions. For example, during high-speed switching, the Miller capacitance of the MOSFET will resonate with the trace inductance, causing voltage spikes and oscillations. If you only shorten the physical distance, but ignore the matching of the driver chip’s output impedance and the gate resistance, or do not place appropriate high-frequency decoupling capacitors near the gate, then switching loss and electromagnetic interference problems will still exist. Understanding the nature of these interactions allows for targeted component selection and layout.
I remember one time when I was debugging a board and it was clear that all the parameters were in line with the theoretical calculations, but there was an error triggering problem. Later I found out that the power supply ripple of the driver chip was too large, which affected the switching characteristics. So you see, sometimes the problem is not in the layout itself but in the details that are easily overlooked. In that case, we measured and found that when the motor commutated with high current, there was a peak ripple of up to 2V on the 12V gate drive power supply, which directly caused the power tube to hover near the threshold voltage, causing erroneous turn-on. Later, a small LC filter was added to the power inlet of the driver chip, and a separate shielded wire was drawn from the power module for power supply, and the problem was completely solved. This reminds us that power integrity is often a prerequisite for signal integrity, especially in mixed-signal systems.
Another point I think is particularly important is not to think too ideally about the design. In actual applications, factors such as temperature changes, mechanical vibrations, etc. will affect performance. I am accustomed to leaving enough margin during design. It is not a simple safety factor, but an adaptive adjustment for specific application scenarios. For example, for a drive mounted on a mobile device or machine tool, I would intentionally reinforce the solder pads for the high-current terminals and avoid placing vias directly under the power devices to prevent vibration-induced fatigue fracture. At the same time, the selection of component ratings will also consider the derating curve caused by temperature rise, rather than just looking at the data sheet parameters at room temperature.
Nowadays, many designs are pursuing miniaturization, but when it comes to motor drives, I think sometimes it is a good thing to be larger to leave room for heat dissipation and room for debugging. After all, we are making industrial products, not consumer electronics. Reliability is more important than compactness. The larger board area means that more effective heat-dissipating copper foil and heat sinks can be arranged, and the high-voltage creepage distance can more easily meet safety regulations. I once saw a design where the heat sink was placed close to the electrolytic capacitor in pursuit of miniaturization. As a result, the capacitor was heated for a long time and its lifespan was greatly shortened, causing the repair rate of the entire machine to soar. In the industrial field, maintenance costs and downtime losses are far more important than the size of the circuit board.
When it comes to signal integrity, my views may be a little different. I think that instead of spending great efforts to isolate various signals, it is better to completely separate the strong and weak current areas from the beginning. I usually divide the entire board into several functional modules and design each module independently and then consider the connections between them. This not only ensures performance but also simplifies the debugging process.
I would physically divide the board into a power area, a drive control area, and a low-voltage signal interface area. Each area should be separated by a clear “trench” (copper-free area), and power and signals should be spanned through specific connection points. This modular thinking allows you to test or modify a certain area (such as the drive circuit) independently during debugging without worrying about disturbing other parts. It also facilitates later function changes or upgrades.
Finally, what I want to say is that the most taboo thing in motor control board design is to copy theories or other people’s plans. Each project has its own particularities, ranging from load characteristics to working environment. Really good design must be based on a deep understanding of the application scenario. You can tell at a glance that the board is customized for this specific application. It feels different when used. This is probably the value of experience. Although it sounds fictitious, everyone who has done it knows how big the difference is.
I have been thinking about something recently: Why do many people always think about the heat dissipation issue in a very complicated way when making Motor Drive PCB? It seems that all kinds of advanced materials must be used to solve it.
Actually, I don’t think this matter is so mysterious.
Take base materials as an example. Many people stare at the so-called high thermal conductivity materials as soon as they come up. They think they are ridiculously expensive and difficult to buy. I have seen a project team wait for two months for delivery in pursuit of a few tenths of a percent improvement in thermal conductivity. As a result, the progress of the entire project was delayed.
Sometimes I think we are too superstitious about parameters? Thermal conductivity is of course important, but it is not the only criterion.
I did a very interesting experiment and made a test board using ordinary FR-4 and then made some adjustments to the layout to spread out the devices that generate a lot of heat to leave them enough space for heat dissipation. As a result, the temperature control was better than some boards made of expensive materials.
Of course, this depends on the specific application scenario.
If you are making ultra-high-power equipment such as motor drives with tens of kilowatts, you really need to seriously consider material issues. In this case, talking to a professional Heavy copper PCB manufacturer will help them know how to find a balance between copper thickness and heat dissipation.
But I find that many people rush to upgrade materials without even doing basic layout optimization. Isn’t this putting the cart before the horse?
Seemingly basic things such as how to place power devices and how to route wiring often have greater impact than material selection.
An engineer I know is particularly good at working in a limited space to evenly distribute heat through reasonable device arrangements rather than overheating a certain area.
Another point that many people tend to overlook is environmental factors.
No matter how well-made your board is, it will be useless if it is installed in an airtight chassis with any high thermal conductivity materials. The most exaggerated case I’ve ever seen was when a customer complained that their board kept overheating, only to find out they had put the board in a metal box with no ventilation at all.
So when I do design now, I will first ask what the final application environment will look like and then decide what aspects to work on.
Sometimes adding a heat sink or adjusting the direction of the air duct is more effective and cheaper than changing the base material.
After all, PCB heat dissipation is a systematic project and cannot just focus on a certain link.
You have to start with device selection, then proceed to layout and routing, then material selection, and finally consider the heat dissipation design of the entire machine. If any link is missing, problems may arise.
I increasingly feel that good design is not about how many advanced materials are used, but about finding the most reasonable solution under various constraints.
Many people think that making a motor drive board can solve the heat dissipation problem by stacking materials and thickening copper foil. I have seen too many projects that start with a plan to use 3oz or even thicker boards. In fact, it’s not that simple.
The key to determining whether a board can withstand high currents and work for a long time is often not the difference in thickness. Think about it! How does heat escape from a board? It must have a passage! Can the heat be taken away just by making the wiring thick? Not necessarily.
I have encountered many cases because I am too superstitious about the value of copper thickness! I thought everything would be fine if I just used a heavy copper plate! The result? The board is still very hot! What’s the problem? It’s the details that haven’t been noticed.
For example, copper coverage is often ignored! Many people think that just making the main lines bolder and thicker will do the trick! Just lay some thin ground layer in other areas! This idea is actually quite dangerous! Because heat will spread! If the thermal conductivity of the entire board is uneven! The heat will build up in certain places and form hot spots!
I have seen a very typical example! There was a team that insisted on using the thickest boards when working on a motor drive project! They found a manufacturer that specializes in heavy copper plates to customize the materials! As a result, during the test, it was found that the temperature in a certain area still exceeded the standard! After careful inspection, I discovered that the problem was in the layout – they had placed several power devices too close together! Although there is a thick copper layer underneath each device! But there is no effective connection between these copper areas!
This is like turning on several heaters in the room but closing all the windows!
So when I do design now, I will pay more attention to the overall heat dissipation path planning instead of simply pursuing the maximization of a certain parameter! An effective heat dissipation path needs to be like planning an urban transportation network to ensure that heat can flow smoothly from the heating core to the thermal boundary or radiator. For example, in addition to paying attention to copper thickness, we also need to carefully plan the array arrangement of thermal vias, how they connect to the internal copper layer, and how to use the board frame or mounting holes as additional heat dissipation outlets. Sometimes, designing a dense array of thermally conductive vias under critical power devices to quickly conduct heat to the copper layer or heat dissipation substrate on the back side has a much more significant effect than simply increasing the thickness of the front copper foil.
Of course, I’m not saying thickness isn’t important! In some cases, it is indeed necessary to use 3oz or even thicker plates to meet the current carrying requirements!
But what I want to emphasize is that you can’t just look at this indicator and conclude that this board has no problem with heat dissipation!
A truly good design should be the result of comprehensive consideration of various factors – including the thermal conductivity of the material, the rationality of the layout, the actual level of the manufacturing process, etc.! For example, the thermal conductivity of the substrate material itself (such as about 0.3 W/mK for FR-4 and 1.0-3.0 W/mK for highly thermally conductive aluminum substrates), the impact of solder mask coverage on heat dissipation, and whether the soldering process will form voids under the pads to hinder heat conduction, are all details that need to be taken into consideration.
Sometimes you will find that slightly adjusting the layout or changing the way you lay out the copper can achieve better results than simply increasing the thickness!
And from a cost perspective, it’s more cost-effective, right?
After all, heavy copper plates are more difficult to manufacture and more expensive!
So my suggestion is not to rush to decide what specifications of materials to use. First, analyze carefully what kind of heat dissipation solution your application scenario requires!
After all, every project is different and there is no fixed formula that can be applied!
You have to adjust your design plan according to the actual situation!
For example, for motor drive systems that need to work in high-temperature environments for a long time, it may be necessary to pay more attention to the heat dissipation efficiency of the entire system rather than just the performance of a certain circuit board! This may mean that the PCB heat dissipation design needs to be co-simulated and optimized with the chassis air ducts, external heat sinks and even liquid cooling systems to ensure that the heat can ultimately be dissipated to the external environment of the system.
In short, I think the fun of engineering design lies in the process of constant trade-offs and optimization. Finding the most suitable solution to the current problem is the most fulfilling thing, isn’t it?
Many people think that making a motor driver board is just a matter of stacking high-power devices. In fact, that is not the case at all. I have seen too many projects get stuck in the details, especially the small gate drive part. If it is not handled well, the entire system will not be stable.
I also made a mistake when I first came into contact with this. I always thought that if I selected the parameters of the MOSFET, everything would be fine. As a result, as soon as the board was powered on, various inexplicable false triggers occurred, and the heat was also serious. Later, I gradually realized that what really determines whether a Motor Drive PCB can withstand harsh working conditions is often not the most expensive power tube, but the design of the entire current path, as well as those easily overlooked protection links. For example, if the gate driver you use does not respond fast enough or has poor anti-interference ability, the MOSFET switching may have problems in an instant, which may cause the efficiency to drop, or the tube to explode directly.
Speaking of which, we have to mention the choice of boards. I found that many engineers use ordinary double-sided panels to make small and medium-power driver boards in order to save costs or for convenience. This may be okay under low currents, but once the power increases or it needs to be operated at full load for a long time, a problem arises – the temperature of ordinary copper-thick traces rises too fast, and the voltage drop is obvious when carrying large currents, which directly affects the output capability.
At this time, it is particularly important to find a reliable Heavy copper PCB manufacturer. They can provide boards with twice the copper thickness. Although the price is more expensive, the current carrying capacity and heat dissipation performance of the current channel are completely two levels, and the reliability is not improved at all. It is much more cost-effective to spend this money on basic materials than to worry about problems later.
I have a profound experience in layout: Never put control signal lines and power loops too close to each other. I used to have a board because the PWM signal line was bypassed next to the Drain pin of the MOSFET. As a result, the noise introduced directly interfered with the ADC value of the current sampling to the point where it was impossible to see, and the motor started to rotate. Later I learned that strict zoning of strong and weak current is an iron rule, and the analog sampling loop must be completely wrapped with a ground wire.
Another point that is easily overlooked by novices is the location of the decoupling capacitor. In theory, you have learned that you need to put a small capacitor next to the power pin of the chip to filter out high-frequency noise, right? But when actually drawing on the board, it is easy to just put it and think it’s done. In fact, this “next to” is very particular – the capacitor must be as close to the chip pin as possible. If the lead is long, it will be as if it is not placed. I am used to directly drilling holes on the back of the chip to put the capacitors to another layer to lay copper connections.
In the final analysis, the design of Motor Drive PCB is an art of balance: you have to consider power density and heat dissipation; you want to pursue response speed but also ensure electromagnetic compatibility; you want low cost but dare not compromise on reliability and safety… There is no one-size-fits-all solution.
Therefore, when I design now, I seldom copy the previous drawings. I have to re-evaluate each time based on the specific application: What are the load characteristics? How harsh is the working environment? What are the restrictions on volume and cost? If you think about these clearly before starting, the success rate will be higher.
Of course, experience is also important – for example, what kind of topology is suitable for using discrete MOSFET bridge arms and when should I directly use IPM modules; how to match the gate drive resistors to ensure switching speed without causing oscillation; how to deal with thermal stress when laying copper over a large area… Many of these things are summarized after going through pitfalls.
I think the most interesting thing about hardware design is this: there is no standard answer, only trade-offs. The sense of accomplishment brought by successfully lighting up a complex board every time is also real. This is probably why I still like to do this after so many years.
I have always felt that many people think about the design of motor driver boards too complicated. It seems like you have to follow a certain standard template. In fact, many times what you really need to pay attention to is not those parameters or certifications that sound particularly advanced.
Let’s take a project I recently came into contact with as an example. The customer emphasized from the beginning that he wanted to find a manufacturer that could make thick copper PCBs. They think that if the current is large, thick copper must be used. This is certainly true. But I later discovered that their real problem was the layout. They put the power section and control section too close together without proper isolation. The result is a mess of signal interference.
No matter how thick the copper foil is, it cannot solve the fundamental problem. Sometimes we are so obsessed with a specific specification that we ignore the rationality of the overall design.
I’ve seen many engineers get extremely nervous when designing gate drive loops. I wish I could make the line width as short as possible. This is of course important. But I think it’s more important to understand how electricity travels. The line you draw is just a physical path. The real current will look for the loop with the smallest impedance and go back to form a complete loop. If you only focus on the short line from the driver to the MOSFET gate and ignore the design of the return path, the entire loop may still have a lot of interference. So I usually recommend drawing the entire current loop first to see if it’s really compact rather than just measuring the physical length of that line.
When it comes to PCB standards, many people will immediately think of IPC. Indeed, the IPC standard is very detailed and divides products into several levels. Class 3 is generally considered the most demanding and is suitable for automotive and industrial applications that require high reliability. But I don’t think we can use standards as a simple shopping list.
Let me give you an example. Once we made a batch of boards according to a very strict IPC Class 3 requirement. All parameters were met including lamination strength and copper thickness. However, in the actual aging test, a batch of boards still developed micro-cracks under specific temperature cycles. Later we discovered that the problem was that the thermal expansion coefficient of the material did not exactly match our actual application scenario. The standard stipulates the Tg value and peel strength, but it cannot cover all the ever-changing practical application environments.
So my opinion is that the standard is a good basic framework that can guarantee a basic lower limit of quality, but it cannot replace your engineering judgment.
Especially when it comes to fields such as automotive electronics or industrial control, you will find that many customers will require manufacturers to have certifications such as IATF16949. This has become an entry threshold. It represents a quality management system, but this system ultimately relies on people to implement and understand the specific needs of the product.
Back to the motor driver board itself, I think its core challenge is how to balance the relationship between power density, heat dissipation performance and signal integrity. This is a dynamic trade-off process rather than simply stacking specifications. For example, if you choose thicker copper in pursuit of greater current carrying capacity, this will of course increase the cost and make processing difficult. It will also affect heat dissipation because the copper foil is too thick and the heat may be more difficult to conduct. You need to evaluate whether this choice is really worth it from a system perspective.
A good design should be simple and efficient. It does not need to use all the most expensive materials and the most complicated processes, but it must be the most suitable solution for that specific application scenario. This requires the designer to have a deep understanding of the working principle of the circuit and not just be able to draw pictures or read data sheets.
So next time you start designing a new Motor Drive When PCB, you might as well put down the long list of specifications and ask yourself what task the circuit is supposed to complete, what its working environment is, and which factors are the real key to its performance. Then you go to the appropriate manufacturer, whether it is an ordinary PCB factory or a capable thick copper PCB manufacturer, to communicate your real needs instead of throwing them a cold technical document. This may lead to a more reliable and economical result. After all, the ultimate goal is to make a product that can work stably rather than a drawing that just meets the standards, right?
I have always felt that choosing the right supplier is sometimes more troublesome than the technology itself. When we worked on the motor driver board project before, we encountered a setback. At that time, I was just looking at the quotations and found a factory that looked quite cheap to make Motor Drive PCBs. However, the samples came out with various problems, including severe heat generation and noise during operation. Later, when I took it apart, I found that the copper thickness was uneven in several places, which was obviously due to poor workmanship.
Therefore, I now pay special attention to the actual process level of manufacturers, especially those manufacturers that claim to be able to produce Heavy copper PCBs. It doesn’t mean that they advertise that they can make thick copper plates. You have to see how many similar projects they have done and whether they have experience in dealing with large currents. Some manufacturers’ equipment is new, but engineers’ understanding of heat dissipation design and current distribution is still at the theoretical level, and the manufactured boards are prone to problems under actual high loads. For example, in thick copper PCBs, uneven current density distribution may cause local overheating, accelerate material aging, and even cause thermal failure. An experienced manufacturer will proactively manage heat by optimizing routing, using thermal via arrays, and considering the etch factor of the copper foil, rather than just meeting basic copper thickness specifications.
When it comes to testing, we can’t be careless. I have seen many manufacturers talk about their tests in a very exaggerated way, but when I actually go to the site and look at their laboratory equipment, I find that either the old machines have not been calibrated, or the test items are simply incomplete. Is the temperature cycle test done? Does the vibration test simulate the actual installation environment? These details often determine how long the board can run stably after being installed with the equipment. Especially in application scenarios such as industrial motors, the environment may be very harsh, and vibration, dust, and temperature changes are all normal. For example, a rigorous temperature cycle test will simulate rapid temperature changes from cold start to full load operation to check the reliability of solder joints, vias and material interfaces, rather than just a static high-temperature storage test.
The current supply chain environment is also quite challenging. Sometimes your design requires the use of a special substrate or a specific thickness of copper foil, but the supplier tells you that it will take three months for the material to arrive, which delays the progress of the entire project. A good supplier should be able to predict these risks in advance and either have stable material preparation channels or can provide proven alternatives to discuss with you.
For example, when a certain high-frequency board is out of stock, they can recommend available materials with similar performance based on key parameters such as dielectric constant, loss factor and thermal expansion coefficient, and assist in necessary design fine-tuning and verification testing, instead of simply saying “no way”.
In fact, after dealing with suppliers for a long time, you will find that the really reliable ones are often not the best at selling themselves. They may not talk much, but the questions they ask every time are critical: What kind of motor is this board used on? What is the temperature range of the working environment? Do you need to consider dustproof and moistureproof? The more detailed the questions asked, the more trustworthy the manufacturer is. Because behind their questions is thinking about the potential failure modes of the application scenario, for example, asking whether the motor is a servo motor or a stepper motor can help them determine the back electromotive force and switching noise level that may exist in the drive circuit, so that they can take measures in layout and shielding in advance.
My current approach is to bring all potential suppliers into actual projects to test the waters. It doesn’t have to be a big order. You can start cooperation with small batches first to see their response speed and quality stability. Some manufacturers are very enthusiastic when accepting small orders. Once you place a large order, their service attitude and quality control become lax, so you need to be particularly vigilant. Small-batch trial production is like a stress test. It can not only test the consistency of its process, but also observe whether its engineering support team is in-depth. For example, for a small impedance deviation found in production, whether they actively trace and adjust the process parameters, or they try to get rid of it by saying “within the specification range.”
After all, selecting a supplier is not a one-time purchase but a process of establishing a long-term cooperative relationship. You have to find partners who truly understand your product needs and are willing to work with you to solve technical problems rather than simply throwing the drawings over and waiting to receive payment. This relationship is built on multiple technology iterations. For example, when you design a more complex stack structure to increase power density, they can provide practical optimization suggestions for your blind and buried via design and lamination scheme based on their process capabilities, and jointly avoid production risks.
After working in this industry for a long time, I feel more and more that good supply chain management is actually an art. It requires finding the delicate balance between technical capability delivery reliability and cost control. This balance will continue to adjust with market changes and technological development. There is no fixed formula that can be applied. It all depends on experience and judgment. For example, in the face of higher switching frequencies and heat dissipation challenges brought by emerging third-generation semiconductor devices, previously qualified suppliers may encounter bottlenecks in new material applications (such as ceramic substrates, highly thermally conductive insulating films) and precision processing, which requires managers to continuously evaluate and guide the supply chain for technological upgrades.
Many people think that making a motor drive PCB is as simple as stacking thick copper materials. This idea is actually quite one-sided. I have seen many projects in the early stage where engineers only focus on finding manufacturers that claim to make thick copper plates. It seems that the thicker the plates and the heavier the copper layer, the better everything will be. As a result, the performance of the board is not up to standard or it is simply unusable. The problem is often not with the material itself.
The real difficulty lies in making the different parts of a PCB work together harmoniously. If you think about it, the core mission of “Motor Drive PCB” is to amplify weak control signals safely and reliably to “drive” the big guy – the motor. It’s like having someone in a small room whispering instructions (control loop) and someone driving heavy machinery (power loop). If the room layout is not good and the sound insulation is poor (electromagnetic isolation), the conductor’s voice will not be heard at all.
So choosing the right partner is particularly critical. The value of a reliable “Heavy copper PCB manufacturer” is not just how thick the copper foil can be laminated. They have to really understand how electricity runs on the board and how heat accumulates. For example, how can the direction and width of a large current path be designed to reduce impedance and avoid becoming an antenna? How should the control signal lines be routed to avoid strong interference areas? These details cannot be solved by standard processes alone, and require manufacturers to have deep application understanding and process accumulation. Sometimes, in order to pursue the ultimate low parasitic inductance and “higher” switching frequency, it may be necessary to adopt an unconventional layered design locally, which is a huge test for the manufacturer’s processing accuracy and consistency.
I’ve been through the trap myself. In the early days, in order to save costs, I found a factory with ordinary craftsmanship to make samples. The static test of the board was fine, but the high-frequency noise exceeded the standard when it was loaded. After a long time, I found out that the ground plane processing of the power loop and control loop was too random. Later, I changed to a factory with real experience. The engineers participated in the early layout and took the issues of thermal management and signal integrity into consideration at the design end and it was a success.
This industry’s requirements for “PCB” will definitely become more and more stringent in the future. As the voltage platform and power density of motor drives continue to rise, “higher” performance indicators have become the norm. But this is not just a material upgrade, but also an improvement in system-level design capabilities and manufacturing processes. Those factories that can only process according to drawings will have a narrower road in the future; but partners who can participate in the customer’s research and development process and provide solutions will be truly valuable.
In the final analysis, a good driver board is the art of balance, which is to find the optimal solution between performance, reliability and cost. This requires both engineers and manufacturers to step out of their own comfort zones to truly understand the challenges in each other’s fields in order to create products that can stand the test of time.
I always feel that many people’s understanding of motor drive PCB is a bit off. Everyone always likes to stare at those complex multi-layer designs and high-end processes. It seems that the more layers and thicker the copper, the more advanced the technology. Actually that’s not the case. I have seen many projects blindly pursue the so-called “high configuration”. As a result, the cost has increased a lot, but the actual performance improvement has been minimal.
The really key points are often overlooked. Whether a PCB can work stably in a harsh environment often depends on the most basic things. For example, is the selection of boards really suitable for high temperature and high humidity environments? Is the connection between the solder pad and the high current trace designed to be strong enough?
These details may seem inconspicuous, but they are the key to determining the life of the entire board. I have encountered some situations where the design itself was fine, but the production link was lost, causing the later failure rate of the entire batch of products to soar.
When it comes to choosing a thick copper PCB manufacturer, this is a matter that requires experience. You can’t just see if the other party has the equipment to make thick copper. What’s more important is to see if they have actual cases and experience in handling high-current applications. Some manufacturers can make it look good, but the processing of internal vias or the bonding force between the copper foil and the substrate cannot withstand the test of long-term high current. If problems start to occur in a year or two, the losses will be huge.
For products such as inverters, the PCB plays a role more like a silent cornerstone. It does not need fancy functions but must be absolutely solid and reliable. Every cycle of current on and off and every cycle of temperature tests its physical limits. So my point of view is very simple. Don’t always think about piling up technical parameters. Spend more time on basic reliability and process matching. Finding a manufacturer that truly understands the application scenarios of your product is better than anything else. After all, what we ultimately want is not a circuit board that looks high-end but a core component that can work stably for a long time.
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