Want vendor recommendation for fab and partial assembly

I am designing a 4 layer board. I will want to get the boards fabbed and assembly help with some fine pitch ICs and SMT power semiconductors. The quantity will be small; I am guessing 3 to 6 boards and I would like to get assembly help with 10 - 15 devices on each. Probably tin/lead solder because that is what I use in my lab. I prefer 2 oz copper on top and bottom if that can be properly etched for 0.5 mm lead pitch. I am in USA and I would want a rapid service.

Can anyone recommend a good vendor to fabricate the boards and do the partial assembly?

Direct response from a vendor is OK. My design still needs a few days so I have a chance to tweak the design if needed for vendor assembly preferences.

A public response may have advantages but if a private message better stays within the spirit of this forum that is OK also. Thanks for any recommendations.

Isn’t lead already banned from the industry altogether? (You can use it, but I think the assembly business can’t.)

Assembly service isn’t cheap. Especially the first set up phase for each board is what costs. Also changes to set up cost; the actual assembly not so much. Therefore what you want to do is the least cost-effective option: many boards, small quantities. I don’t remember any details, but it may be hundreds of $ per design. But I may be wrong, too.

JLCPCB offer a small run pcb production and assembly service. I am not affiliated with them in any way other than as a customer but have been pleased with their costs and quality. They have a reasonable range of common parts but you probably need to check if there is anything unusual. Offer a fast turn around. Lead or lead free, ENIG, 2oz copper, coloured soldermask are all available options but they are based in China. Probably quite a useful starting point for a price though. I suspect that an EU or US based supplier will be more expensive.


Pcb shopper is also quite a helpful site to compare prices from different vendors.

DHL shipping from China (3 day) costs the same as getting the boards from 50 miles away. China boards cost less.
I love and hate JLCPCB assembly but I also love/hate the local assembly houses. Because I am going to have troubles anyway, I should be unhappy for less money.
One local house only makes boards in multiples of 3. JLCPCB is 5 at a time. When you pick a vendor come back and see if any one is using it. Each vendor has laws that are hard to learn.

medical, military and aerospace have an exemption

In my experience in USA, tin/lead seems to be universally used for prototypes and by engineering labs. I have been working on my own for a while and my experience that way is limited in the last few years. I was in a Microsoft lab during 2016-2017. We could do very little soldering but I think even there we had tin/lead.

I can remember when the industry was being pushed to eliminate lead in solder: The industry went off to try to find a solution, and came back and said no, it could not. Then more arm twisting and again the industry came back and said no, it could not. There were maybe 2-3 cycles of this before the industry yielded to pressure from environmentalists.

I started soldering electronics in 1965. I have personally tried ROHS solder and found it to be a lot more difficult to use. I have a hard enough time with fine pitch, I do not want to invest in more soldering equipment/supplies and that is why I am looking for assembly help.

Thanks, John

I will have to take another look at JLCPCB. But I wonder whether the “no touch” approach is suitable for this project given that I want only partial assembly.

They actually have quite a good system - you upload the centroid and can select which components you want placed. You can exclude any ones you don’t want placed. There will be solder paste reflowed on the DNP components however - I have found it OK to handsolder extra components onto these - hot air helps. Also, you don’t get to keep the stencil - but its not much use on a partially populated board.

I know you said you didn’t want any more soldering kit but even fairly fine pitch stuff is quite manageable using an electric skillet/frying pan which are very cheap.

Better still, build a reflow oven - these can be pretty accurate and cheap.

Thanks again. What do you mean by “centroid”? I have ordered previously from JLCPCB; in fact that is the only supplier from whom I have ordered the few KiCad boards I have had fabricated.

I am thinking perhaps they can work with a different set of gerbers for producing a stencil; with only the parts I want them to place. I do not think that the cost of some added service would be a problem. I am thinking to ask them about doing that.

But on the other hand, I have a rework tweezer. And at least for Rs and Cs it is pretty easy to place them onto solder containing pads with the tweezer. But perhaps a counterexample is SOIC which would normally be easy to hand solder on clean pads; not so if the pads all have solder.

Here is a link to all the parts JLPCB keep on hand. (click the in stock Butten) To keep the price down I use their parts as much as I can and put 95% of the parts on the top side. Then hand solder a couple capacitors on the back side. I do the hand soldering of a couple of through hole parts. If you can play the game right, I get the boards in two weeks with most of the parts soldered on including shipping, for less than the parts alone in the US.

Thank you. My first and most important part is not in stock… :frowning:

But Digikey has them so this should not be impossible.

What part?
I use a toaster oven to do soldering. Also have a hot air gun. There are many ways to stick down parts.

I’ve used https://circuithub.com/ a lot at work and been pretty happy. They assemble in Massachusetts, getting boards fabricated in various places depending on selected lead time and other factors. Doing only a partial assembly is no problem, we do that all the time. You can mark each part you want to exclude as “not populated” in the online quoting tool. You pay extra for the domestic manufacturing, but they are more flexible than JLC and depending on the design can offer shorter minimum lead times.

Like others have mentioned about JLCPCB: they will make a stencil for your design and so there will be solder paste on any unpopulated parts as long as there is stencil opening in your CAD. Also, I’ve never tried to get leaded solder, not sure whether or not they would do that.

All quoting and ordering is done by uploading CAD files (no gerbers) so it’s quite easy to put your design in and see what they offer in terms of minimum lead time and associated price.

Recent orders have been subject to somewhat unpredictable (but minor) delays due to the global supply chain issues going on, but I suspect that impacts most or all vendors…

LM5155 is TI only and has 0.5 mm lead pitch, in addition to a grounded belly pad. I will take a guess that if I had 5 of them to solder I might damage the IC and the board at one of them. But now add some other tight pitch parts and there would be a lot of damage. I have a hot air tool but that requires care not to blow away the part and my hands can be unsteady. A beer beforehand might help (seriously.)

Thanks I will look them up. There is also an assembly shop in Bellevue WA which I have used indirectly. But I am unsure who will be interested in so small a job.

I hate that package. I found it works better for me to extend the pads to bring them out from under the part. I think in KiCAD the call that “hand solder pads”. I would use solder paste and hot air.

If the whole point is to get someone to solder down the LM5155 and JLCPCB will not then forget them. (I see that at one time they had the part but do not now)

I put fat corner pads on almost everything (and also extend the pads outwards) because it does help. From my present perspective, this job represents something of a corner case in terms of SMT assembly difficulty and it makes the most sense to me to offload the more difficult part of the assembly if I can do so. Otherwise maybe I just need to keep a few beers on hand. Does anyone have pretzels? :slight_smile:

Altogether one board might have 150 - 200 components, and sometimes it is easier to mount those myself rather than to kit them. If I build several boards, I am likely to leave them in varied stages of completion pending test results of the first one. That is tough to do when an outside shop is doing the assembly.

This is a view of my footprint for that package. At least it is not a BGA. I once attempted to solder a tiny 4-ball BGA MOSFET; could not get anywhere with that.

That’s not my experience. I’ve ordered semi-assembled boards from JLCPCB 2 or 3 times and they’ve removed the unpopulated footprints from the stencil for me so that these pads had no solder on them. I didn’t need to ask for this and didn’t need to make this change to my files. But I guess it can depend on which person are preparing the files for you. Or they might have started doing this more recently.

We use JLCPCB in China - fast turnaround, top quality and low cost. They do everything from prototype manufacture up to full board assembly & test. Fast turnaround, thery also do express shipping. We can’t get anything close in the UK…

Thanks everyone for the inputs. JLCPCB tells me that they can order parts which they do not have in stock. I have used them previously for fab only so will look into this further. I have not yet asked them about solder. With solder mask, maybe it is OK if they use ROHS solder for the ICs and I use tin/lead elsewhere. (I used to build many prototype boards which had only tinned copper; no solder mask and no silkscreen.)

There are a few places in the UK and depending on the complexity a couple of weeks turn around is typical. its been a bit of a problem for the last 18months due to COVID and the electronics shortages so a recent run of IMS took 6weeks instead of 10days.

The biggest problem I am facing in the UK is ODB++ … more assemblers are demanding it because the only way they can stay competitive against China is by cutting costs (and ODB++ enables this… 30min setup vs 4h+ with the risk of errors due to knife and forking…) or offering additional services - flying probe.

With Kicad lacking ODB++ its becoming a major problem for using uk-based assemblers