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How to Choose the Best PCB Assembly Manufacturer for Your Electronic Project


When you finish your PCB design and PCB fabrication, the next step is to perform PCB assembly and final integrity electronic project testing.

PCB assembly is a very critical work in the whole of electronics projects manufacturing process. There would be a big cost and time lost if there is an anti-repair failure form the process of PCB assembly itself.

Actually,there is plenty of worldwide manufacturing capacity manufacturers for PCB assembly. If you’re looking for a industrial PCB assembly manufacturer for your next circuit board,most time it can be difficult to determine who is the best option to assemble your circuit board. Different assemblers offer different levels of service, different capabilities, and access to different processes and materials.

There are a lot of options to consider when selecting an ideal PCB assembly manufacturer for your project: some manufactures focus on turnkey PCB assembly;some of them just focus on mass production assembly;some of them is for simple assembly;some of them focus on high density component assembly;some of them focus on quick PCB assembly but only for partial components loading…etc

In this blog, my goal is to to positively share my thoughts that how to choose the best PCB assembly manufacturer for a new electronic project. You might be in a position where you need more advanced and high quality assembly services, or it might be your first time engaging with a full-service manufacturing firm. Either way, there are some questions you should ask your PCB assembly manufacturer and yourself to ensure you decision on the best assembler for your new project.

Where to Find the Best PCB Assembly Manufacturer

There are a lot of PCB assembly houses in the world,also in China.Some of them is world class capacity,such as:

Foxconn,
Jabil,
Flextronics,
Celestica,
Sanmina-SCI,
Benchmark Electronics.,etc.
These are biggest EMS contract companies in the world who only focus on very large volume assembly.

Most of others is the medium capacity PCB assemblers who locates in the different places of the world.So it could be very easy to find some ones at your local places and you can personally audit them and understand each other face by face. But, mostly your local PCB assembly cost could be very much high comparing with the cost offered China PCB assembly suppliers .
So,most PCB designers like to do PCB assembly in China get a better price minimization.

How to Find the Best PCB assembly Manufacturer In China

Mos of my prototypes PCB assembly was done in local companies here in Canada, but the cost was really high and some times the lead time was very long. So,I tried to attempt to use the PCB assembly suppliers from China.

I remember when I put my first batch of 4 layers circuit boards (with a size 88mm X 95mm) into production with a Chinese PCB assembly manufacturer who I searched them by internet. They presented themselves in internet by advertisement of total assembly cost 30$ for 20pcs plus free shipping cost-really attractive! Then I decided to have a try on them although I knew this was a potential impossible cost that something unknown hidden in. Next steps was very happy: I created the order on their web and paid it by Papal with my credit card which was very impressive. By the way, they had packaged services: PCB fabrication+components sourcing+SMT assembly,which made my time saved(at least I did not need spend the extra time to purchase complements and no need to find PCB fabrication suppliers,either.

Two weeks later, I received my order of 20pcs.Apparently looked very nice from the package of the box.I opened the box and sorted out my circuit boards to have visual inspection, everything was good, the components with their orientation at it’s correct place. I was very happy to see this and prepared to program them and perform complete electronic functional test.
Instead of to fully power on the assembled PCB board, I was very careful to firstly detect the output +5v and +3v voltage by the test points accordingly, as there was a very expensive component OSD3358-512M-ICB from Octavo Systems assembled on this PCB,I do not expect this component to be destroyed by some unexpected issues.

The result was really not good as the voltages from the test points can not be continuously detected out: 3pcs of 20 boards can be read the voltage very weakly,but others could not be detected out at all. I asked the supplier to send their engineering files back for me to see whether there was some error in PCB files they made. No errors found out after I double verified all the files they worked. I have talked back to supplier ask them to have a instigate,something must be wrong in assembly process. But they insisted on the some design errors from me was the root cause of the problem. So, disputation went on around 1weeks.

This was a very headache to me as i was unable find out evidence to prove the supplier made the wrong work.Meantime i could not find my error, either. What’s more I assembled prototypes very previous version at Canada and no issue found,for this new version i just made a minor modification the schematic drawing which could not be so big problem. Finally I dared not to use these board and had to give up negotiation with current suppliers as they always said “errors in design” but no more words helpful to me.

Another headache to me was that the problem found in Christmas holiday and I had no chance to re-order this from my old local assembler,but i had to submit my contract with my customer after Christmas holiday. I had to to find solutions to this problem or else I had to lose my customer.And, I had to go back to china manufactures as America and Europe assembly manufacturers closed on their holiday (I did hope i had assembled that 20pcs at my local company and did not spend 30$).

I went back to look for suppliers by internet again: the same view as last time I saw: many suppliers presented 5$, 10$,…30$ + free shipping cost for prototypes assembly. But now I was very careful to select suppliers as I knew I did not want to buy trouble although it was only 30$, I was willing to pay 300$ to by the PCB assemblies that they can work and I can use them. The urgent time was not allowed me to despair again.However, I reviewed the suppliers presented at first 5 pages but it was really difficult to identify who was the real of professional suppliers.No one of them could present a referable solution to the problem I met from the previous supplier.

But when I visited WELLERPCB and doubted their presentation “high quality” and passed the problem I had to them.I was happy that their guys judged that the problem could be from the PCBs, the root cause could be that the insufficient copper thickness in the through holes lead to the break current when the PCB board powered on by electricity.I appreciated that their guys asked me to ship the previous problem boards to them and they would have damage to the assembled boards and make a analysis, and meantime they would make 20pcs assembled boards for me but price not only in 30$.

I still had doubt on that but I had to try this due to I had no other choices then. So I shipped the problem PCBA boards to them and asked them to prepare new 20 PCS of assembly,but did not start any work until they found any problem on my previous problem boards.

Four days after my shipment they received the problem boards and disassembled the high cost component OSD3358-512M-ICB. And then they made a basic analysis according to their judgment: the result was what they judged: poor cooper thickness in the 0.2mm via holes, some of them is only 8um, and most of them was broken out when the PCB board withstand high temperature in reflow process. This lead to the dis-continuous current when the boards powered on. So the root cause was from PCB fabrication, but the detail reason was complicated.At least I trusted their words that the PCB board is a core component of electronics devices. So, it was the time to ask them to start new 20pcs of assembly, and they did.

8 days later I received the assembled boards from WELLER,I worked steps as before to detect the output voltage firstly: it was good. And next days I powered on the boards and started firmware program process, everything was well.

And after that I kept working with WELLER and talked more with them and had some summaries here to share PCB designers as a reference to choose PCB assembly supplier in China:

  1. If you look for suppliers by internet, normally, do not relay on the suppliers that listed on first pages, most of them listed at first pages by their advertisement with high cost spent to attract the traffic.
  2. You’d better to ask more questions you concerned and welcome their questions to you (normally processional suppliers much more concern on your products rather than you price).
  3. It will be more trustable if your friend could share the suppliers who they have good impression on.
  4. It will be good if you can have a personal visit to meet their teams and to have feeling on them.
  5. Ask some core questions, it is better to take your past problems to them and ask them for answer. They will satisfy you if they are real professional in manufacturing process.
  6. Normally, bottom price would be very easily to take you some potential risk and troubles.
  7. Clearly specify your requirement (such as PCB base material, copper thickness, surface finishing, etc)in your document to avoid any misunderstanding on specification. Professional supplier always like to work with professional customers.
  8. Qualification and certification checking: If you’re manufacturing a medical device, an automotive product, military or aerospace hardware, or other regulated products, make sure your manufacturer has certifications attesting to their quality systems in these areas. Quality assurance programs are required for some products, and a manufacturer should be able to produce proof of compliance on demand. The best PCB assembly manufacturers for regulated products will be able to spot any design choices that might reduce yield and reliability.
  9. Here are some of the questions you might ask yourself before you start searching online for a PCB fabrication and assembly manufacturing partner:

PCB Fabrication, PCB Assembly, or Turnkey?

Electronic manufacturing consists of two high-level steps: PCB fabrication and PCB assembly. Some companies only provide one service and not the other. The term “turnkey solution” also gets thrown around a lot when referring to PCB manufacturing, as well as in other industries like software. Very simply, a turnkey manufacturer provides PCB fabrication, PCB assembly, and component sourcing services into a single package. Some companies will offer PCB fabrication with turnkey assembly through a partner as a single service package

SMT LINE WITH YAMAHA MACHINE
SMT LINE WITH YAMAHA MACHINE

Before you order components, be sure to check the assembler’s attrition requirements. Small components (such as 0402,0603) can sometimes get lost on the factory floor or on the running of feeders, so it helps to purchase 5% to 10% extra to account for this(at least 30PCS of spares). If you don’t feel comfortable sourcing your components for a new project, or you don’t have time to go through the exercise, then a turnkey solution is a viable option. A turnkey manufacturer will add a markup to component costs (this can double your component costs in some cases), and they may add an additional fee to their regular PCB fabrication + PCB assembly costs.

PCB assembly DIP wave soldering
DIP WAVE SOLDERING PROCESS

Once you’ve found the best PCB assembly manufacturer for your project, your design and your plan will go through several stages before it gets to a fabrication line. The design will need to pass a review before a price can be quoted, and the PCB board can be released for production. If you’ve already gone through a process to ensure your PCB board’s fab and assembly requirements match the manufacturer’s capabilities. You can rest assured you’ll have a high-quality product at the end of the process.