AllPCB assembly? - Page 1
Forum section: electronics / general

author: phil from seattle
author_rank: Super Contributor
timestamp: November 22, 2020, 04:19:49 pm
content: I am looking for feedback on ALLPCB assembly. I have a 4L 100x100mm board that I want assembled - 100 pieces to start, maybe push to 200. 30 unique parts - 110 total. ALLPCB is quite a bit less expensive than the other quotes. I have a number of through hole connectors that are easy to get misaligned (I'm tightening this up to reduce the problem but the datasheet holes sizes make for really sloppy alignment) so I am concerned about assembler's ability to make them look good as that will have a significant affect on the customer's perception.Any feedback greatly appreciated.

author: Yansi
author_rank: Super Contributor
timestamp: November 22, 2020, 04:32:31 pm
content: As far as I can tell, these guys do not offer assemblin THT components, do they?

author: phil from seattle
author_rank: Super Contributor
timestamp: November 22, 2020, 05:01:53 pm
content: Hmmm, They ask about DIP on their quote page but now I need to take a closer look at that.If they only do SMDs, then I'll stick with JLCPCB...

author: Yansi
author_rank: Super Contributor
timestamp: November 22, 2020, 06:24:32 pm
content: Well, isn't AllPCB and JLCpcb the same company behind?

author: lutkeveld
author_rank: Regular Contributor
timestamp: November 22, 2020, 08:25:17 pm
content: ALLPCB's mother company is Jiepei, I dont think its affiliated to JLC.I have quite some experience with their assembly service.Their service works well and their communication is professional.The SMD placement is accurate and the joints look great.For THT you really have to pay attention to your pad dimensions and thermal reliefs.Most smaller batches get assembled by hand, which does not always give the most professional joints.The joints are 99% functional, but sometimes they are a bit messy.Its best to check the boards, sometimes touch them up by hand, and do some flux cleaning on the backside.You can pay extra for wave soldering, which might be worth the extra cost.Be sure to make mis-allignment as difficult as possible. Use clear silkscreen on the board to indicate how to mount them.If you pay extra, they can send one board first for testing, and after approving they manufacture the rest.Most often, if I know my design is functional, I choose the picture option. Then they assemble one, send a picture, you approve and they will assemble the remainder.Im available for consulting work to get your assembly outsourced in the right way, if you are interested, send me a DM.If you do it well, ALLPCB is a great assembler at a reasonable price.Usual turn-around is about 5 weeks from ordering to receiving.

author: phil from seattle
author_rank: Super Contributor
timestamp: November 22, 2020, 11:39:08 pm
content: Thanks, that is extremely helpful. I am in the process of tweaking the board so assembly errors are less likely. My biggest concern is the pluggable screw terminals - 26 of them The datasheet shows a 1.05mm pin and specs a 1.6mm hole - needless to say the parts are practically swimming. I have a test board being made trying different hole sizes and inter-part spacing to see what works best to keep them fairly lined up before soldering. A big unknown for me is the manufacturing tolerance of the parts - I don't want to make them too tight and have a different batch not fit at all. The data sheet is silent on the tolerance. The actual parts I have measure almost exactly to spec.Thanks for your offer but this is just a part time gig for me. I am operating on a shoe string, as they say. I'd be ecstatic if I sold 200. Maybe it breaks big and I can afford those kinds of services.

author: lutkeveld
author_rank: Regular Contributor
timestamp: November 22, 2020, 11:56:32 pm
content: Have you already made some boards by hand?If its do-able for you, its do-able for the assembler.With a 1.05mm lead diameter, the smallest you could realistically go is 1.2mm, see:https://www.pcb-3d.com/tutorials/how-to-calculate-pth-hole-and-pad-diameter-sizes-according-to-ipc-7251-ipc-2222-and-ipc-2221-standards/That, or a bit bigger, could reduce accidental header rotation/skew.If you have a lot of THT components, I would definitely pay the extra cost for wave soldering.Will look cleaner, and is more reliable.Do not make your thermal reliefs too thick, that will make soldering a lot easier.As a simple checklist for assembly:-Make sure your components can be bought from Digikey/Farnell/Mouser/LCSC. They dont source from Ali or other obscure places.-Your BOM has to at least include quantity, designators and partnumbers.You can leave the cell empty for simple caps/resistors and let them choose.I usually make two rows: example MPFN and actual MFPN.If you fill in the example, they can choose themselfs based on the example.If you fill in the actual, then they know they MUST use that part-Make sure your position file has all your SMD BOM items on there.-I always include a screenshot of the 3D viewer so they have an idea of what it should look like.Or take a good picture of your prototype.

author: phil from seattle
author_rank: Super Contributor
timestamp: November 23, 2020, 01:58:23 am
content: Wow, thank you for all that.I have a proto I'm working with now. Had a batch of 5 made by JLCPCB and have hand completed 3 with the TH components so far. The terminals are a bitch to get straight - my concern is not theoretical. One sees a lot badly aligned screw terminals on ebay/ali/... I will do at least one more turn on the proto before a full batch. I have a full BoM (SM and TH) with LCSC part numbers, even the 603 Rs/Cs and pin headers. I will have to look at the wave solder costs to see if my market can bear it. I think a professional looking board commands a higher price.This is a variation on a board I sell already - I provide the SMD version ("Unkit") along with a through hole parts kit to complete it. It uses simpler screw terminals that lock together so it is easier to line up. I've already sold over 100 of that board so I'm pretty confident that it works. I am hoping that getting out of the "some assembly required" ghetto will increase my available market and allow me to charge a higher price. I'm optimistic but cautious as well. I may test the market for the new board this way (SM only plus parts kit).

author: Nominal Animal
author_rank: Super Contributor
timestamp: November 23, 2020, 04:19:27 am
content: Quote from: phil from seattle on November 23, 2020, 01:58:23 amAlignment jig for soldering?This may sound crazy, but: do one with clamps so you get it absolutely right, then saran-wrap it, and use it as a template to make a jig using hobbyist clay; either air-drying (like Staedler Fimo Air) or oven-cured (like Premo Sculpey). The saran wrap stops it from sticking or dirtying up the original. Use play-doh, blue-tack, or soft wax to fill in holes and cavities that would prevent you from slipping the clay on or off the board. Then cover the board and the components with the clay. Shrinkage is as low as 1% depending on the clay used, but you can use enamel spray paint to both make the jig tighter, give some wear surface, and to add some heat protection (if the air-drying clay you used contains cellulose, and you use heat-resistant paint). See your local hobby stores if they have some clays that are soon going off; often they sell those at a good discount.After you have made the jig, you solder a board by putting all the connectors (or all through-hole components) onto the board, then slide the jig on top, making sure everything seats well and all components correctly placed, then turn the jig-and-board upside down, and solder the components. It is a fit-to-board soldering jig.Drying/kilning the clay does cause 1%-4% of shrinkage depending on the clay, so you may wish to make larger (say, over 100mm long) board jigs from slightly oversized corner pieces (two to six parts), then saw/file/sand them to correct size, and superglue together. Similarly, you may wish to file the corners in the jig (between board and component) a bit, so that they'll seat easier.One can even use these clays for custom enclosures, albeit they have to be a bit thick (or strengthened with e.g plastic fiber netting) and painted with enamel or similar hard-wearing paints. Useful for gift trinkets.Note: I don't make anything to sell, only for myself or to give as a gift, so this may make zero business sense for you. Just wanted to let you know this is an option you might try out.Of course, an even easier way is to use thin superglue on the parts to locate them when soldering. Just don't breathe the cyanoacrylate fumes..

author: phil from seattle
author_rank: Super Contributor
timestamp: November 23, 2020, 06:43:03 am
content: Heh, I actually made a simple jig to hold the screw terminals in place - it consists of two thin pieces of wood as long as each set of terminals (80mm for 10 of the 2 pin kind) and a BABC (big-assed binder clip). It works but is kind of unwieldy. If I were doing 100 myself I would do something similar to what you suggest. I don't know if a Chinese hand assembly worker would do that or just wing it.I've actually thought about leaving the terminals off the board assembly and doing them myself to ensure a quality job. But 100 would be the outer limit of what I would ever do. And, I'd have to pay myself less than minimum wage...

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: November 23, 2020, 07:26:43 am
content: Just modify the hole size smaller. But not too tight, factories hate that.I have a board that uses JST XH connector that have pins bend and it take more effort to push in even with the standard footprint JST recommend.Factory said "can we use domestic China alternative connectors that has straight pins instead".

author: phil from seattle
author_rank: Super Contributor
timestamp: November 23, 2020, 08:25:55 am
content: Quote from: 48X24X48X on November 23, 2020, 07:26:43 amThat is what I am doing with the test board. When I get it back, I will know the goldillocks size.

author: manton
author_rank: Newbie
timestamp: November 23, 2020, 09:06:52 am
content: I 3D print jigs for doing through hole assembly all of the time. There is a good ESD rated PLA now from 3DXTech, and I've also used conductive ABS. I've found the crappy ABS I have only useful if the sections are quite thick, otherwise it tends to fall apart, since the layer bonding is terrible.Usually you can get the 3D models of the through hole parts from the manufacturer, to make sure the jig will fit. I usually leave 0.5mm or so of extra slop to account for component tolerances.Another thing you could do for the headers, is a trick that SparkFun uses. Instead of putting the pads in a straight line, they stagger them slightly, so that even though the holes are quite a bit larger than the pins, the pins touch on one side, forcing alignment. It looks like it works pretty well.

author: phil from seattle
author_rank: Super Contributor
timestamp: November 23, 2020, 04:57:08 pm
content: Yes, I've been doing the pinheader slight misalignment trick for years. If done right, you can't even tell on the assembled board. Recently had to go back and re do it when I moved to Kicad.Unfortunately, you can't do that with 2 pin components.