Prototype board assembly - Page 1
Forum section: electronics / general

author: emarthinsen
author_rank: Newbie
timestamp: September 24, 2019, 11:25:56 pm
content: We have 4 boards with about 200 components each. The components are 0402, mostly. We underestimated our ability to assemble these by hand and are looking for an alternate way to get them assembled. Does anyone have any recommendations for resource in and around the Boston, Massachusetts area to get this done? We have the PBCs and all of the components (on cut tape), but need the boards stuffed and reflowed. We're open to a company, maker space, etc. that might have the equipment we could use for a bit, a contractor, or a small shop that can handle the assembly. We're also open to other ideas, if anyone has any. Thanks in advance!

author: rea5245
author_rank: Frequent Contributor
timestamp: September 24, 2019, 11:31:30 pm
content: Googling for "PCB assembly boston" yielded some interesting results.- Bob

author: sokoloff
author_rank: Super Contributor
timestamp: September 24, 2019, 11:32:27 pm
content: I'd head out to (or at least call)Worthington Assembly. Tell Chris D I sent you and he got some work from opening his assembly house to the NE Factory Tour group.

author: sokoloff
author_rank: Super Contributor
timestamp: September 25, 2019, 12:33:46 am
content: Or, if you want to meet and talk to a handful of New England PCBA shops, check outwww.d2p.com(tomorrow and Thursday in Marlboro).No connection (other than planning to attend tomorrow).

author: asmi
author_rank: Super Contributor
timestamp: September 25, 2019, 11:39:06 am
content: This conversation isn't gonna go very well. "Cut tape" for PCBA shops is like red rag to the bull

author: pisoiu
author_rank: Regular Contributor
timestamp: September 25, 2019, 04:24:16 pm
content: Quote from: asmi on September 25, 2019, 11:39:06 amIf all goes well, maybe in 1 year I will offer a PCBA service which will love cut tapes. But there is a lot of work until then. Sorry for offtopic.

author: GerardG
author_rank: Regular Contributor
timestamp: October 10, 2019, 07:31:41 am
content: Quote from: pisoiu on September 25, 2019, 04:24:16 pmWe designed a JEDEC compatible tray to use cut tape in a pick and place machine.This is a feature we mostly sell to prototype manufacturing companies that come over for a demonstration of the Neoden4 Pick and Place.It is also used in PnP machines from other brands.http://bit.ly/pt-insta

author: SMTech
author_rank: Frequent Contributor
timestamp: October 10, 2019, 08:10:13 am
content: With the greatest respect cut tape is still a pain the behind even if you have a holder for it and is still only a solution for small qty of part numbers and a nightmare for tiny light components in plastic tape (because they will jump out). Most parts are basically worthless, cut tape is fine as long as you buy a decent length so there is enough left to handle, then you can just load them in the machine in standard feeders. 30cm or so should be acceptable to most assembly houses, especially if you prep them nicely by adding a covertape extension and splicing on headers and footers saving them some prep time. However you do need to check with them first, same machines might not like splicing, or need it done well, some might need more wastage to get started. Some modern feeders don't peel off the covertape, they stick a blade under it and shift it to one edge, the cost of that is a few potentially wasted parts & is offset by those feeders being very quick to load and unload. It also wouldn't hurt to get a cd marker pen and write the value/part number physically on each strip, they won't be in those nice labelled bags for long.I have both an official strip holding accessory and some DIY ones for our essemtec machine but by preference I would still load a strip into a feeder, on CLM feeders ~10CM is still just about handleable while loading into a feeder without prep and if I cross my fingers I can load 603 upwards in exact qtys and have a reasonable chance of getting away with it. Loading into a feeder is quicker, the part is in exactly the same place every time, nothing jumps out of the pocket and the machine knows where a feeder is, every strip on a tray needs defining separately and then you have to get the covertape off without stuff hopping out, or stcking to your hand when you inadvertently touch an uncovered strip during the process. Trust me, no assembly house will LOVE strips for long, not even one you setup to do so.

author: pisoiu
author_rank: Regular Contributor
timestamp: October 10, 2019, 08:32:43 am
content: I do not have your experience, but before seriously considered to optimize my pnp machine design for cut tapes, I made some tests down to 0201, any lengths up to 50cm and they do not jump out when peeling the tape. Not even one. How do yours jump, I do not understand? My cut tapes were secured with double adhesive tape on a solid surface. Are your tapes secured in a way that allows them to vibrate when peeling off? I am thinking that may be the cause.

author: SMTech
author_rank: Frequent Contributor
timestamp: October 10, 2019, 08:52:43 am
content: Try sticking down plastic tape with holes in the bottom(as all plastic tapes do) with sticky tape. It will not stick reliably* and also the components inside with stick to the adhesive and then fail to pick.Paper tape is the easy one, its also the one where you can pretty much guarantee the parts in it are cheap enough to just overbuy to a qty that works in a feeder meaning buying little tiny strips is just silly.There is another issue with sticky tape, once you stuck it down many tapes are quite a bugger to clean off again afterwards and you want your solid surface to be clean and flat for next time, which is why some of the commercial cut tape holders don't use sticky tape, and yes that does add some opportunity for vibration. But then that will always be the case for a movable fixture unless your solid surface is your machine bed and that introduces an ergonomic element, its unlikely its exactly a nice area to lean over and work on. Unless you have guide rails on it putting down 50cm of tape in a straight line is harder than you think and for many parts that will matter.*Often little plastic strips have been wound up into a tiny coil, all they want to do is wind back up again.

author: pisoiu
author_rank: Regular Contributor
timestamp: October 10, 2019, 09:41:01 am
content: My thoughts were to use guide rails and intermediate fixtures on which to put the tapes. Intermediate fixture will have predefined locations to be installed and guide rails will have to keep tape pockets in precise known locations. Also, openpnp does have function to recognize tape positions by looking for advance holes. I have yet to design those... Putting tapes directly on the machine bed is bad for 2 reasons, one is ergonomics, as you pointed, other is machine efficiency, the Z travel is quite big and it takes time. In my particular design it is not even possible, my nozzles does not have enough Z travel to touch machine bed. I need intermediate fixtures for ergonomics and to calibrate tapes to known positions, I do not want to program positions each time for a new batch.Your other thoughts are quite helpful, thanks. I will make some more tests.

author: GerardG
author_rank: Regular Contributor
timestamp: October 10, 2019, 10:26:57 am
content: We have solved the alignment with a precise machined pin at the end of each strip.No adhesive tape needed.