Which fab house for just a few turnkey prototypes? - Page 1
Forum section: electronics / general

author: skyjumper
author_rank: Regular Contributor
timestamp: February 26, 2020, 05:15:11 am
content: Hi All...I'm in the US and I designed a board that has a lot of parts (61 unique parts, 141 parts total) all SMD. The board is 2 sided but all the parts are on just one side, and I tried to avoid very fine pitches and hidden vias and such. Design was done in Eagle CAD. I would like to get 2 or 3 assembled, depending upon price (component price in qty 1 is about $US60). Seeed Studio has a nice quoter, and they wanted $US 132 per board for 10. I don't mind $US132 per board so much, but I don't want to buy 10 because, somewhere, I probably made an error.I read other threads here and found discussions about fabs that make boards, in particular thread about non-Chinese fab houses and I checked a few, but I would appreciate a recommendation for a good place (anywhere in the world) to get 3 boards assembled at a reasonable price with good quality. Reading some reviews about Chinese based fabs, it seems I could easily be looking at a nightmare if I choose the wrong one. And, trying to source parts from Chinese places has been very difficult, so I stuck to parts available on Digikey and took a lesson from that. And of course, the virus...So who have you been happy with for a project like this?Thanks!

author: filssavi
author_rank: Frequent Contributor
timestamp: February 26, 2020, 08:02:44 am
content: That is a very small board and if Don’t have any PITA package( BGA, QFN and such) you really should assemble it yourself, this is also good for the first prototypes, as you can solder and test at the same time (eg solder the power supply section only and then test it to make shure all voltages are right and stable) it also allows you to easily pinpoint defects, as it will most probably be in the section you soldered lastAlso take into account that going the assembly route you will lose a lot of time going back and forth with them to make shure that all the files are right as they will go over eve with a very fine tooth comb (they don’t want to be blamed obviously) usually this process takes more time than just assembling one boardI personally can recommend hqpcb (www.hqpcb.com) the only problem is that everything is mandarin only (both website and employees)

author: SMTech
author_rank: Frequent Contributor
timestamp: February 26, 2020, 09:31:28 am
content: I can tell you how I roughly estimate the costing for something like that:Data Import/Setup Time + (Number of BOM lines x handling time for loading that part into a feeder etc) + Number of parts x very rough average time to place 1 component. +components+PCB+stencil.As you might guess the loading time dwarfs the build time, so the assembly price radically scales between 1 and 10, in your example you could easily spend 3+ hours cutting open little bags of parts, adding header tape, loading and double checking. The build itself is only a couple of minutes/board on a modest machine although it would be pretty safe to assume there's a whole bunch of parts you need to place manually due to packaging/qtys involved, which completely messes with several of the time assumptions.This complexity is right on the edge where manual/automated placement methods are considered, people aren't robots so introduce another potential avenue for error would be where I was coming from. However there are more than a few people on this forum who think they can build this board with tweezers perfectly in 45mins so who am I to argue with that?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 26, 2020, 01:34:45 pm
content: Just regarding BOM reduction, you may consider using resistors (or capacitors or whatever) in series or parallel combinations, 2, 3, even 4 at a time, to optimize out some of the less frequently used parts. Or using resistor packs, which cost about the same per part but can replace up to four identical values, or be arranged into eight other values:https://www.edn.com/resistor-combinations-how-many-values-using-1kohm-resistors/Mind the per-element power rating is lower in a resistor pack, so you may need much larger ones, or bigger single resistors, to handle power where applicable.Similarly, using diode or transistor pairs can be convenient to reduce parts count.It is somewhat of a pain to route (and occasionally swap pins and parts) this way. But if your time isn't worth as much as the assemblies, why not!As for assemblers, MacroFab is fine, if probably not any cheaper than what you've already looked at; PCBCart is another Chinese one, but YMMV due to current events.Also know a local guy who could probably do it for less, but with kitting, shipping and availability, it might not be worthwhile?Tim

author: OwO
author_rank: Super Contributor
timestamp: February 26, 2020, 02:56:02 pm
content: What I usually do is use JLC SMT to solder all the passives, and then solder the chips myself.

author: skyjumper
author_rank: Regular Contributor
timestamp: February 26, 2020, 04:26:28 pm
content: Thanks for the tips everyone. I have done the hand assembly thing in the past, although it's been a few years. I commandeered the toaster oven and built a timer to do the reflow profile and so on. The first time I did one it actually came out okay, but most of them didn't work and a lot of time was lost. If it was a smaller board I would give it a try, but sadly my eyes are not what they used to be.I submitted to PCBWay for a quote. I don't read or write Mandarin, but I'll check out MacroFab and PCBCart. I think JCLSMT only will do an assembly if I use the parts they stock, but I'll check again.

author: skyjumper
author_rank: Regular Contributor
timestamp: February 26, 2020, 10:30:42 pm
content: Maybe I should ask another way... Who did you have a horrible experience with ?

author: skyjumper
author_rank: Regular Contributor
timestamp: February 27, 2020, 07:21:41 am
content: I just got my quote from PCBWay, very nice pricing but, 60 to 75 days lead time! I know, the virus...

author: skyjumper
author_rank: Regular Contributor
timestamp: February 28, 2020, 09:21:52 am
content: Does anyone have any experience with ShenZhen2U they would want to share?