
Heat Dissipation Challenges and Solutions in PCB Circuit Board Design
Circuit boards are more than just that green board in a phone
I’ve seen too many people treat various certifications as a shield. Last year, we partnered with an assembly company PCB that seemed to have all the necessary qualifications for a project. They showed us a thick stack of certificates, but the first batch of boards had soldering problems. This experience taught me that those certificates hanging on the wall are at best entry tickets; the real test lies in every detail of daily production.
Now, when choosing suppliers, I pay more attention to how their production line workers treat a circuit board. Once, during a factory inspection, I picked up a board and asked the operator why it needed rework. He could clearly state the IPC standard deviation value for each solder joint. This ingrained quality consciousness is more reassuring than any beautifully packaged certification.
Many people think that passing certification is the end of the story, but that’s just the beginning. The factory we’ve worked with the longest re-trains us on IPC standards every year, and even veteran employees undergo regular assessments. Their quality control team leader once told me that they’d studied the same standards for ten years, and each time they reread them, they made new discoveries. This dedication to quality is the key to ensuring product reliability.
I remember a batch of motherboards for medical equipment; the customer required them to meet the most stringent standards. Several suppliers said they could do it, but hesitated when it came time to accept the order. Finally, a small factory took it on; their boss practically lived in the workshop, overseeing every step of the process. Upon delivery, with dark circles under his eyes, he said, “This time, we upgraded all the processes in the factory. Although we only made money on this batch of boards, the entire production line has been significantly improved.”
Traceability is often talked about in too abstract terms these days. A good traceability system should be like an old craftsman’s woodworking, leaving natural marks at every step. Our most satisfying partners never use complex systems; they simply record the operator’s number and timestamp at each workstation. If a problem occurs, the specific step can be located within half an hour. This simple and effective management is more reliable than those fancy digital solutions.
Ultimately, finding an assembly plant is like finding a partner; just looking at qualifications and certificates is far from enough. You need to see how they handle defective components, how they handle emergencies, and even how they treat their frontline employees. These details reveal the true level of quality.
Sometimes I’ll specifically go to the factory after get off work to see if the night shift workers’ operating procedures are the same as the day shift workers’. Manufacturers that maintain consistent quality are the ones you can trust long-term. Good quality isn’t something you inspect; it’s something everyone in every position does with dedication.
I’ve seen too many people oversimplify PCB assembly. They think finding any factory that can solder components is enough—this kind of thinking will inevitably lead to problems.
A truly reliable assembly company should be a technical partner. I remember a client who, trying to save money, hired a small workshop to make motherboards for medical devices. The first batch of samples revealed serious solder joint defects. Three reworks failed because the same problem persisted—they hadn’t provided basic soldering training according to the IPC standards required in the medical industry.
Many people overlook the most basic thing: certification isn’t just a certificate on the wall, but a daily work habit. One factory I worked with randomly inspected boards on the production line every week, having employees check the IPC manual to find problems. Those who found the problems accurately received a reward. This practice of embedding standards into their DNA is more effective than any high-end equipment.
Three years ago, we had an industrial control project that required operation in a high-temperature and high-humidity environment. At the time, the supplier proactively suggested potting protection and even provided accelerated aging test data from similar previous cases. This kind of judgment based on practical experience is the most valuable – they know which processes and materials are truly effective in solving the problem.
Some PCBA manufacturers like to boast about the advanced nature of their equipment, but what truly determines quality are often the unseen details, such as temperature and humidity control in material storage or the way employees wear anti-static wristbands. These are the key indicators of professionalism.
Recently, an interesting phenomenon has emerged: more and more consumer electronics brands are demanding complete traceability records from their supply chains, from solder paste batches to employee numbers. This is actually forcing the entire industry towards greater standardization, which is a good thing.
Ultimately, choosing an assembly plant is like choosing a marriage partner; looks don’t matter. What matters is their attitude towards standards – are they meticulous, and are they willing to work together to overcome problems? This is the foundation for long-term cooperation.
I’ve recently been dealing a lot with a circuit board assembly factory. They mainly handle the assembly of relatively complex electronic products. In fact, many assembly companies are now shifting in this direction.
Previously, people thought that finding a factory to solder components onto a board was enough. But now, customers prefer ready-to-use finished products. This involves seemingly simple steps like casing installation and cable connections, which actually demand meticulous attention to detail.

I’ve seen factories that can’t even implement basic anti-static measures properly. Workers handle boards carelessly, and packaging is substandard, resulting in problems by the time they reach the customer. These details truly reveal the professionalism of an assembly plant. For example, in cleanrooms, reputable factories require employees to wear anti-static clothing and wrist straps, and material racks are grounded with conductive materials. Laxly managed factories often overlook these, causing chips to fail due to electrostatic discharge during transport—a hidden damage difficult to detect during factory testing.
Flexible printed circuit boards (FPCs) are becoming increasingly common, especially for products requiring bending, where traditional rigid boards are simply impractical. However, FPC assembly is significantly more complex than regular PCBs, requiring a completely different level of precision in the equipment. Because the substrate is flexible polyimide, alignment requires real-time correction using a visual positioning system, and the soldering temperature profile must be more precisely controlled; otherwise, delamination or copper foil breakage can easily occur. Furthermore, FPC pads are typically smaller, necessitating micro-pitch mounting technology to ensure accurate component placement.
A friend who works in the smart wearable industry learned this the hard way last year. Their product used very fine flexible circuitry, but the equipment at the factory they hired was too old, causing frequent crimping problems. After switching to an experienced assembly plant, their yield rate immediately increased from 60% to over 90%. The new factory introduced an automated optical inspection system to scan the connector coplanarity immediately after crimping and used vacuum suction fixtures to prevent FPC warping during reflow soldering. These targeted measures directly solved the previous pain points of connector cold solder joints and circuit tearing.
In fact, good assembly plants now embed testing into each process step. Testing after everything is completed is too late to discover problems. While on-the-fly inspection adds time, it ultimately saves costs in the long run. For example, after surface mount technology (SMT) is applied, online testers are used to check for short circuits and open circuits, and functional tests are performed before assembling the casing. This allows for rapid identification of defective processes. Statistics show that this distributed inspection strategy can reduce rework costs by 40% because early-detected defects only require localized repairs, while disassembling and reassembling the entire device after completion can damage the already assembled precision structure.
I appreciate suppliers who are willing to spend more time communicating upfront. After all, each product has different requirements; some require special heat dissipation, while others are particularly sensitive to weight. Directly applying standard procedures often yields poor results. For example, medical equipment requires low-temperature soldering processes, while automotive electronics require reinforced conformal coatings. Experienced engineers will analyze the BOM (Bill of Materials) in advance, recommending heat sinks or high thermal conductivity solder paste for chips with high heat generation, and suggesting the use of thinner packaged components to reduce weight for portable devices.
Recently, there’s also a trend of many assembly plants offering design support services. Having witnessed too many problems in actual production, early intervention helps customers avoid many pitfalls. This value-added service will gradually become a core competitive advantage. Specifically, this includes providing optimization suggestions for PCB layout, such as avoiding placing sensitive components on the board edge where they are susceptible to stress, or recommending component packages that are easier to assemble. Some factories also establish shared component libraries to help customers directly select material models that have been validated in large quantities.
Ultimately, the electronics manufacturing industry is all about the ability to control details. Advanced equipment alone is not enough; the most valuable asset is a group of truly skilled, experienced technicians. For example, experienced technicians can judge furnace temperature deviations by the shine of solder joints and predict faults by listening to the sounds of equipment operation. This kind of tacit knowledge requires long-term practical accumulation, and it is precisely this intangible experience that allows high-quality factories to quickly resolve unexpected process problems at critical moments.
I’ve always found choosing a circuit board assembly company quite interesting. Many people immediately ask about prices or look at equipment lists, but the most crucial thing is whether the company truly understands your product needs.
I remember last year we had a project that required producing a small batch of industrial controller boards, and we contacted several assembly plants. One company offered a particularly low price, and their workshop was lined with brand-new placement machines. However, when discussing specific process requirements, their engineers kept asking us, “How do you usually handle this type of board?” Conversely, another smaller company, while their equipment wasn’t as impressive, had their technical manager directly point out several potential problems in our design.
This made me realize that judging an assembly company’s reliability shouldn’t be based solely on appearances. Some companies constantly tout “ISO certification,” but the actual impact of these certificates on daily production depends on how they are implemented. I’ve seen factories with all the necessary certifications, yet their production line operations are a mess.
There are many companies like Haibo in the market now, each emphasizing their professional capabilities. But what truly matters is whether they can apply their expertise to every detail. For example, when manufacturing communication equipment boards, some companies simply follow the drawings, while others provide professional advice on everything from material selection to soldering processes.
I think choosing an assembly partner is like finding a spouse; a list of requirements is useless. You need to see if both parties can work together effectively. After all, PCB assembly isn’t simply processing supplied materials; it requires collaboration between both parties to ensure a high-quality product. Sometimes, it’s worth spending a little more to find a truly knowledgeable partner.
When it comes to finding the right PCB assembly company, I think many people are focusing on the wrong things. They’re always looking at fancy service promises, neglecting the most basic things.
I’ve seen too many people stumble at the PCB procurement stage. Some suppliers offer incredibly low prices, only to tell you after you send your design files that certain special materials require additional charges, or that the minimum order quantity is far higher than your needs. At this point, the project is often stuck at a critical juncture, leaving you with no choice but to passively accept their terms.
Truly reliable partners will lay out all the possibilities clearly from the outset. For example, they’ll proactively inquire about your product’s application scenario and then suggest the most suitable material type. Sometimes we choose ordinary FR4 material to control costs, but experienced suppliers will remind us that more specialized substrates might be needed for high-frequency circuit environments.
When it comes to component procurement, that truly tests your skills. Last year, one of our projects encountered a global chip shortage. Our PCB assembly company, which we were working with, solved the problem for us by providing an alternative solution. They didn’t simply replace it with a similar model; instead, they organized engineers to re-evaluate the entire power module design. The value of this deep collaboration goes far beyond the numbers on the quote.
Now, I pay special attention to a supplier’s risk management capabilities. Once, a severe rainstorm caused logistical disruptions, and our partner even mobilized air freight resources to ensure the timely delivery of critical materials. These kinds of unexpected events best test a supplier’s true capabilities.
Finding a PCB assembly partner is like finding a marriage partner; superficial conditions are useless. The key is whether they can face difficulties together. Those who always say “no problem” are the most worrisome. Good partners will honestly disclose potential risks and prepare contingency plans in advance.
Recently, we were working on a medical device project. Our partner not only completed the standard PCB assembly but also helped us improve our production testing processes. They designed specialized testing fixtures based on the product characteristics. This kind of service that exceeds expectations is truly valuable.
Ultimately, choosing a supplier cannot be based solely on price or superficial promises. Observe their actual reactions when you encounter specific difficulties, and see if they truly understand your product needs. This process requires time to adjust, but finding the right partners will make subsequent project progress much smoother.
I recently chatted with some friends in the hardware industry and discovered an interesting phenomenon: many startup teams, when looking for PCB assembly companies, immediately head to manufacturers that claim to handle large orders. Actually, this depends on the stage—if you’re still working on prototypes, looking for mass-production factories can easily lead to losses.
Last year, our team learned this the hard way when developing smart home sensors. We thought finding a large manufacturer would facilitate mass production, but they required a minimum order of 500 pieces, and the mold-making fees alone were a huge burden. Later, we switched to a company called Haibo, which specializes in small to medium-batch assembly PCBs, and that was the right approach. They even handle the assembly of single boards, which is perfect for our trial-and-error R&D phase.
There’s a misconception in the industry that flexible production is all about advanced machines, but the key is still the manufacturer’s cooperation. Once, we finished revising the design drawings at 2 AM and sent them to Haibo’s engineers, who were still online confirming details with us. This flexibility is far more valuable than simply looking at equipment parameters.

Environmental certifications are also worth considering. Standards like RoHS are indeed basic requirements now, but what truly tests a manufacturer’s daily implementation efforts is their commitment to them. I remember once visiting their workshop and finding that even the solvents used for washing boards were biodegradable. Such attention to detail is reassuring, as nobody wants their products to be stalled by environmental testing when shipped overseas.
Ultimately, when choosing a PCB assembly plant, size and compatibility are more important than anything else. Sometimes, smaller plants are more willing to spend time understanding your product needs; this depth of collaboration is far more important than the number of production lines for innovative products.
Have you encountered similar situations? I always feel that the most challenging aspect of hardware startups isn’t the technical difficulties, but rather the compatibility issues in these manufacturing processes.
I recently talked to some friends in the hardware industry about finding PCB assembly plants. I found that many people initially struggle with whether to partner with large companies. Actually, it depends on the stage of your project.
When you’re just starting out, there’s really no need to chase after those high-end, fully automated production lines. A team I know initially partnered with a small local assembly company for their PCB. Their biggest advantage was their flexibility—you could send them a modification file at 2 AM and they’d respond instantly. That level of cooperation is unimaginable at large companies.
However, smaller companies also have obvious weaknesses. Once, we had a board that required special impedance control. As a result, their testing equipment wasn’t advanced enough, causing signal interference issues across the entire batch.
Therefore, I now believe the key to choosing an assembly service is compatibility, not size.
Many people easily overlook the issue of communication efficiency.
I’ve encountered suppliers with strong technical capabilities but incredibly difficult to communicate with. Every time, requirements had to be relayed through sales, resulting in significant information loss.
Good assembly collaboration should involve direct engineer-to-engineer communication.
Many emerging PCB service providers are now adopting a project manager plus technical support model, which I think is a good direction.
When it comes to cost control, many people’s first reaction is to lower the unit price. However, considering the entire project cycle, the first-pass yield rate is the real money-saving factor.
A factory that did rapid prototyping for us quoted about 15% more than their competitors, but they conducted a detailed Design for Manufacturing (DFM) analysis before production.
In the end, it turned out to be more cost-effective than finding a cheaper manufacturer because it saved time and material waste from rework.
Recently, I’ve noticed a trend of increasingly pronounced regional clustering effects.
For example, the Pearl River Delta region has a very complete PCB industry chain, handling everything from board material supply to post-processing within a radius of 100 kilometers. This geographical advantage certainly reduces many hidden costs.
However, we must be wary of over-reliance on a single region; in case of unforeseen circumstances, the entire supply chain could be affected.
I think a better model for the future might be a combination of core partners and backup suppliers.
Many assembly plants are now talking about intelligent transformation, but in practice, the key is not how advanced the equipment is, but whether the data can truly be integrated.
Once, I visited a factory that claimed to be fully automated, and found that their MES system was still an information silo; real-time data from the production line only generated reports the next day. This kind of digitization is somewhat of a formality.
Truly useful intelligent systems should allow you to see at any time which process the board is at and what the current yield rate is; this real-time information is helpful for decision-making. Finally, I want to say that finding an assembly partner is like finding a romantic partner; you can’t just look at the hardware, you also need to see if your philosophies align.
We had a manufacturer we’d worked with for three years. Their equipment wasn’t the most advanced, but their engineers were exceptionally willing to spend time understanding our product logic and even propose assembly solutions superior to the original design. This value goes far beyond simple OEM manufacturing.
Therefore, when choosing suppliers now, I specifically observe whether their technical team has a sense of curiosity; this is perhaps more important than qualifications and certifications.
I’ve seen many electronics startups fail because they chose the wrong assembly plant. They always thought that finding a factory that could solder circuit boards was enough. In reality, it’s much more complex than they imagine.
I remember a smart home team showing me their experience. Initially, to save money, they chose a small, workshop-style assembly company, resulting in a 30% return rate for their first batch of products, all due to poor soldering and misplaced components. They only stabilized the quality after switching partners with a complete quality control process.
Many startups now fall into the misconception that as long as the design is innovative enough, everything else can be compromised. However, the reality is that even the best design needs reliable assembly to be realized. A professional PCB assembly company I’ve worked with places great emphasis on early communication; their engineers proactively participate in design reviews to identify details that could lead to production problems.
Some clients prioritize price and always try to get the lowest possible offer. But those truly in the know pay more attention to the assembly plant’s quality control system, such as how they inspect BGA soldering and track component batches. These seemingly insignificant details often determine the product’s lifespan.
Recently, the demand for flexible PCBs has increased significantly, placing new demands on assembly processes. Traditional rigid board production lines require equipment upgrades and worker retraining; these hidden costs are often underestimated.
When choosing a partner, I suggest focusing on how they handle exceptional situations. Once, when a batch of components arrived late, my assembly company immediately activated its backup plan and adjusted the production schedule, ultimately delaying the delivery by only half a day. This adaptability is where the true value lies.
In fact, the best partnership is one where both parties understand each other’s business pain points. For example, we once encountered a client who temporarily changed functional requirements, and the assembly team reprogrammed the pick-and-place machine overnight. This level of cooperation cannot be guaranteed by contract terms alone.
Ultimately, finding a PCB assembly partner is like choosing a marriage partner; superficial appearances aren’t enough—you need to assess long-term compatibility. After all, with the rapid iteration of electronic products, nobody wants to miss a market window due to production delays.
Having worked in the electronics industry for years, I’ve increasingly realized that choosing an assembly company is essentially choosing a collaboration model. Many people think they just throw in their blueprints and wait for the finished product, but the reality is often far more complex. I’ve seen many teams initially struggle with whether or not to manage materials themselves, ultimately hindering the entire project’s progress.
In fact, the most troublesome aspect of assembly isn’t the technology itself, but rather the seemingly simple process arrangements. For example, some teams insist on sourcing all components themselves, believing this controls costs and quality. However, they often underestimate the complexity of supply chain management; a small batch of capacitor shortages can halt the entire production line for two weeks. In this case, it’s less about saving money and more about increasing hidden costs.
I prefer to partner with assembly companies that can provide complete solutions. They typically have mature material management systems and can flexibly adjust their procurement strategies according to your needs. Last year, we had a project that used a hybrid model—we sourced the critical chips ourselves, while the assembly plants handled the general components. This ensured the quality of core components while avoiding tedious procurement work.
Many assembly plants are now promoting so-called turnkey services, but I think the key is whether they truly understand your product’s characteristics. Once, we encountered a situation where ordinary soldering processes could damage a sensitive component. A good assembly company would proactively suggest adjusting the temperature profile, while a typical manufacturer might just follow the standard procedure.
Ultimately, choosing an assembly model is about balancing control and efficiency. Complete self-control sounds ideal, but in reality, it might require dedicated procurement and quality control teams, which can become a burden for most startups. Sometimes, delegating appropriately and letting professionals handle their specialties can actually make the project run more smoothly.

I’ve always found finding a reliable PCB assembly company more troublesome than choosing a design solution. Our team stumbled on this when rushing a medical device project—the manufacturer, which claimed to be able to respond quickly to small batches, was three weeks late in delivering.
Many assembly companies and PCB manufacturers like to emphasize their ability to handle any industry. However, the reality is quite different. During a visit to Haibo’s production line, I discovered that they were actually producing industrial control equipment boards on the same line as consumer electronics boards. Although the equipment was interchangeable, workers were noticeably disorganized when switching products.
In medical device assembly, transparency is paramount. Obtaining ISO certification isn’t enough. We’ve encountered cases where flux residue was discovered after soldering. Such details might be insignificant in consumer electronics, but they are fatal flaws for implantable devices.
Small-batch production sounds appealing, but it tests the flexibility of the entire supply chain. Some manufacturers use “supporting orders as small as one piece” as a selling point, but what’s truly needed is for them to understand why such a small quantity is required. We had a sensor project where each order only required fifty pieces to align with clinical testing iterations. If manufacturers are always focused on large-scale production, this logic simply doesn’t work.
Recently, while dealing with automotive electronics suppliers, I discovered an interesting phenomenon: they were actually more willing to accept design changes than medical device suppliers. Perhaps because automotive-grade products have long iteration cycles, their engineering teams are used to repeated back-and-forth during the Design for Manufacturing (DFM) stage.
Ultimately, choosing an assembly plant shouldn’t be based solely on advertised certification standards. It’s about where they actually invest their resources: are they genuinely spending time understanding customer needs or just buying new equipment to maintain appearances? Sometimes, traditional large manufacturers are less reliable than small assembly companies specializing in a niche market; at least they know how to use limited capacity effectively.
I remember a client who makes industrial controllers saying his criteria for choosing suppliers is very simple—whether they dare to show him real-time monitoring of their production line. This confidence is more valuable than any certification, because PCB assembly ultimately comes down to responsibility, not just technical skill.
Recently, while working with a hardware team, I noticed an interesting phenomenon: many entrepreneurs place too much emphasis on circuit board design but neglect a more crucial element—finding the right reliable assembly partner. Even the most exquisite design drawings are just theory; what truly brings an idea to life are the craftsmen who can precisely solder components onto the circuit board.
I remember last year, one of our smart home projects almost failed in the mass production stage. The prototype ran smoothly in the lab, but various strange malfunctions occurred during small-batch trial production. It was later discovered that the foundry’s soldering temperature profile was incorrect. This incident made me realize that choosing an assembly service provider shouldn’t be based solely on the price list; it’s crucial to consider whether they integrate quality control into every detail. For example, some small workshops skip X-ray inspection to save costs, but professional PCBA companies insist on full-process quality control, even with small orders.
Many assembly companies are now offering design optimization suggestions. The industry is shifting from simple contract manufacturing to technical collaboration. Last week, a supplier pointed out that the heatsink design of one of our chips was inadequate and suggested adding a thermal via. This feedback based on manufacturing experience is far more valuable than simply lowering processing fees, as the cost of rework often exceeds ten times the saved processing fees.
I particularly admire manufacturers who dare to disclose their production processes. Last month, during a visit to a PCBA company, I noticed that their workshop temperature and humidity records were posted directly at the entrance, and even the solder paste warm-up time was accurate to the minute. This transparency is more reassuring than any certification. After all, circuit board assembly is a delicate process where even slight environmental fluctuations can impact soldering yield.
Recently, I’ve also noticed a trend: flexible manufacturing is reshaping the industry. The previous minimum order quantity of 1,000 units has been broken down; one manufacturer in Shenzhen is even accepting orders in the hundreds and supports mixed-material production. This means startups can validate product solutions at a lower cost. This flexibility is particularly important for hardware innovation; nobody wants their first batch of goods piling up in warehouses.
Ultimately, choosing an assembly partner is like choosing a marriage partner—it’s not enough to just look at hardware specifications; you also need to consider whether your values align. Manufacturers willing to spend half an hour explaining why your BOM requires resistor accuracy adjustments and proactively reminding you about potential delivery delays due to typhoons are the ones worth entrusting with long-term. They truly understand that a circuit board is not just a collection of parts, but a living entity carrying creative ideas.
I’ve always felt that many people’s understanding of circuit board assembly is somewhat misguided. While everyone is focused on the high-end, fully automated equipment, they’re overlooking a crucial point—what truly determines whether a board can function stably is often not how advanced the machine is, but the human judgment.
Take, for example, a PCB assembly company we worked with before. What I admired most about them wasn’t their dancing robotic arms, but the way their experienced technicians inspected solder joints with magnifying glasses. Once, I saw them debugging a new testing device and discover that a capacitor’s pin bending angle was slightly off; the automated optical scanner had marked it as合格 (qualified). The technician immediately stopped the production line and manually readjusted the component’s position. They later discovered that if they had powered it on as before, the entire power module might have burned out.
This incident really struck me. The industry relies too heavily on standardized processes, losing sight of basic observation skills. Especially with the trend towards miniaturization, 0201-sized components are as small as grains of sand, but you can’t just let them be because machines can mount them. After soldering, I habitually scan the board with a thermal imager; areas with uneven temperature distribution are likely to have cold solder joints—problems that can’t be detected by program settings alone.
Many clients worry that contract manufacturers’ equipment isn’t high-end enough. I think the real concern should be whether they retain sufficient manual verification steps. Last time, during the final testing of an LED driver board order, we discovered a transistor parameter drift. After much investigation, it turned out to be due to batch-to-batch differences in materials. The pick-and-place machine won’t tell you that the tolerances of this batch of components are different from the previous batch.
Therefore, I particularly value whether the assembly plant will note any traces of human intervention in the inspection report. Perfect data generated entirely by automation actually makes me uneasy. After all, circuit boards are meant to be used, not displayed as works of art in a showroom. Sometimes, an extra step, seemingly less efficient, actually prevents bigger problems later.
Ultimately, when choosing a partner, don’t just listen to them boasting about how many temperature zones their production line has; observe how they handle abnormal situations—that’s where their true competence lies.

Circuit boards are more than just that green board in a phone

From disassembling old routers to visiting electronics manufacturing plants, I gradually realized

As an electronics enthusiast, I’ve come to understand firsthand the impact of
- Experto en producción de lotes pequeños y medianos
- Fabricación de placas de circuito impreso de alta precisión y montaje automatizado
- Socio fiable para proyectos electrónicos OEM/ODM
Horario comercial: (de lunes a sábado) De 9:00 a 18:30
