What PCB assembly method do you prefer for small prototype runs?

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1

Hi everyone,

I’m working on a few small PCB prototypes and was wondering what assembly method others prefer for low-volume projects. For a small batch, would you recommend hand soldering, a hot plate/reflow setup, or using a professional PCB assembly service?

I’m mainly interested in reliability and consistency rather than production speed. Also, are there any particular issues I should watch for with small SMD components?

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Hi PCB
Regarding hand soldering.
This actually requires pretty experienced operators. When soldering say a through hole 40 pin header it is all too easy when trying for speed to be TOO quick and have the last few joints faulty. The soldering iron will lose heat after a few quick operations and MUST be given time to recover. When you have a whole board full of solder joints failure to be aware of this can be fatal, and thus costly.

If there is ANY doubt on this issue I would use a professional service and maybe do any “special” bits yourself. All this of course depends on the job.
Cheers Bob
PS: I have seen this scenario on many occasions with new or inexperienced operators. Usually comes down to lack of proper instruction.

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Apart from what @Robert93820 has already covered… smd depending on the component can be very tricky to do by hand. smd resistors and caps and move around as you try to solder the other side as the heat can move back to the already warm side. balled solder pads on under side of chips cant be inspected with home gear, and I would recommend and SMD oven, but you can still have issues if components are on both sides.

with smd chips with side legs/pads at least you can see them to inspect. the idea is to have the correct amount of solder paste. to much and you increase the change of bridging, too little your risk dry joints. For small boards and one off, I would say try it, inspect and fix… but for a run, get the smd solder stencle made up with the PCB.

I would also get a quote from the PCB people as you may be surprised. The can often get the parts cheaper then we can, so the TCO is the same or not much more then you getting the boards made, then buying the parts.

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I would seriously consider a PCB assembly service like JLPCB if you don’t have a love of soldering, perfect eyesight/microscope and a dedicated work area. I had a go at THT and SMD assembly before for some of my projects and did a write-up here: Designing a PCB for assembly

HTH

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Hi Geoff
I have not read this link in detail but looks very complete and understandable.
Well done and is worth looking at for anyone contemplating this sort of exercise.
Cheers Bob

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It ended up as 1 year+ project due to life, etc. The guys on EEVBLOG forums were incredibly helpful too

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I used KiCad to get some PCBs made and used all through hole components, soldering them myself. I’ve done soldering intermittently for many years, so was happy to do that. However, I have not tackled SMD. Silicon Chip magazine have had several articles about SMD soldering, also how to convert an air fryer into a reflow oven. Your library may have copies. You can find the relevant issues by going to the Silicon Chip website, use the drop down menu for articles / content search, put smd in the description and search. Of the 20 or so articles there are 5 or 6 relevant ones.