PNP Conveyor Design - Page 1
Forum section: electronics / general

author: MR
author_rank: Regular Contributor
timestamp: September 04, 2020, 10:43:03 pm
content: Hi,can someone take some pictures of a conveyor design in his pick and place machine? Especially the clamping part of the PCB.I already have some ideas how to implement this but it would still be interesting to see how other people solved this topic.

author: Mecanix
author_rank: Frequent Contributor
timestamp: September 05, 2020, 12:37:34 am
content: Common mechatronic between stations appears to be simple (and primitive) gravity, on chains/rollers with guide rails. Guaranteed to combat inconsistent flatness during assembly and potentially excessive board warpage due to uneven/edge thermal dissipation after reflow!!! It makes up for awesome and reliable products when mounted in enclosures or onto a fixtureThose non-linear forces on the joints and components when those warped boards un-twist is all good stuff. Lets all spend million in assembly lines, I'm convinced already lol

author: MR
author_rank: Regular Contributor
timestamp: September 05, 2020, 02:51:53 am
content: Thanks for the pictures!Although I'm looking for pictures from conveyors inside pick and place machinesI have seen some excessive bent PCBs in the past, many years ago when a PCB manufacturer panelized our PCBs it was a good lesson for us to not let them do it again.Back then we also outsourced the assembly, magically the assembly house also overcame that issue (even without an adapter).

author: Mecanix
author_rank: Frequent Contributor
timestamp: September 05, 2020, 09:52:00 am
content: Went out only two weeks ago to visit two local fab/assembly houses who've, I was told, could have ran a product variants for the company I work for. To find its all side-edge held up as on the pictures (not mine, btw). All assembled that way and reflowed the same. So much capability for boards! Both of those fabulous houses couldn't ensure flatness and hinted about 'randomness' :/ When asked about induced joint strain & stresses when mounting into enclosures during final assembly, both looked at me clueless and couldn't care less.Haven't seen the new Year 2021 assembly lines, bet they are better equipped with flat belt conveying and platform/podium style assembly and induction heating?

author: ar__systems
author_rank: Frequent Contributor
timestamp: September 05, 2020, 01:03:54 pm
content: Quote from: Mecanix on September 05, 2020, 09:52:00 amNot sure what you are talking about. Your first comment appears to be sarcastic but what are you getting at?Flatness of the PCB is not something that assembly house provides. Mostly it will depend on the material of the board and the design. I.e. if you have a solid ground plane on one side and few traces on the other side, the board will warp with near certainty.Induction heating? For reflow? LOL.

author: Smallsmt
author_rank: Frequent Contributor
timestamp: September 07, 2020, 11:02:06 am
content: Take care of stable frames around the panel design!the frame should be 15 to 20mm width around and on bigger panels don't add vcuts to separate PCB's.Frame thickness should be 1.6mm better 2mm to avoid bending.

author: eeviking
author_rank: Regular Contributor
timestamp: September 07, 2020, 03:52:35 pm
content: Most P'n'P clamp boards by raising the conveyor up so the board is held against an edge or clams on the top.MYDATA raise a bracket with clamps on the inside of the coveyour. (Against an edge on the top.)Normally you also have a plate with support pins that raises too.Quote from: Mecanix on September 05, 2020, 09:52:00 amDon't know what issues you have with your products or you are just trolling.But panel warpage is normally a design or pcb manufacturing issue. (copper balance, stackup, moisture etc.)A easy fix could be to use a thicker pcb.Guess if you have some really thin sensitive stuff you could place them in a support pallet like you use in wave solder.How will you transport dual side pcb's if not by the edges?Most processes use support pins or a center support rail. Did you make room for this in you design?Big boards will sag in the oven, but thats what the center support is for.We have some big heavy boards we place vertically in racks right after they come out of the oven to avoid further sagging while cooling.Maybe the 2022 smt line will mount boards vertical to match a Seica flying probe.