How to automate thermal pad (Sil-pad) application? - Page 1
Forum section: electronics / general

author: pauljmccain
author_rank: Contributor
timestamp: January 23, 2016, 08:48:00 pm
content: Hello,I'm currently working on a high-brightness LED project that will consist of an aluminum PCB that gets sandwiched between two cast aluminum pieces, to really dissipate heat and act as the exterior housing. I'd like to use die-cut Sil-pad (or other adhesive-backed thermal pad) to fill the gap between the housing and board. This would need to be a custom die-cut, not a standard TO220 or anything.Problem is, I can't imagine having our guys apply thousands of small labels exactly on the small rectangular boards (40mm x 10mm or so). And I don't think the big companies are doing it by hand in the factories.Can anyone shed any light on how thermal pads are normally applied to the PCB in automated fashion? Ideally, I'd like to use some 3-axis placement machine with a PCB conveyer and vision alignment to stick the labels in programmed fashion, but I can't figure out whether anyone makes machines to serve this purpose. Maybe I'm not searching the right terms, or I can't find the right application notes, but any help would be much appreciated if you know anything about this subject.Thanks!

author: pauljmccain
author_rank: Contributor
timestamp: January 23, 2016, 09:19:10 pm
content: Well, after looking around some more I did finally come across a few older labelling machines. Seems that most of them are geared towards internal printing though, you can't use your own labels.Found one Chinese SMT-line-style machine that has vision and xyz placement, that may or may not work.I think we might just end up using a benchtop xyz table with vacuum, to build a custom solution. Not ideal, but it would be cheap.Also will try to get in touch with Bergquist to see if they have any recommendation. I'll let you guys know what we end up doing.

author: pauljmccain
author_rank: Contributor
timestamp: January 23, 2016, 10:11:49 pm
content: Another lead from a company in Wisconsin. Looks promising, and apparently can flip the board for dual-sided labels? Nice!Model ELC-1100Phttp://www.promationusa.com/elc-1100-p-label-placer/

author: jeroen74
author_rank: Frequent Contributor
timestamp: January 24, 2016, 08:46:40 pm
content: Some PCB manufacturers can silkscreen a thermal interface material directly onto the PCB; Eurocircuits for example can do this.

author: pauljmccain
author_rank: Contributor
timestamp: January 24, 2016, 09:21:19 pm
content: Now THAT would save some major time. Can't find any info on it, I know some manufacturers have a specific dielectric layer between circuit and metal substrate that's more geared towards thermal transfer, but I haven't seen a silkscreened solution specifically for interface/gap filling. That would really be great for this application though, if anyone has any further info!

author: jeroen74
author_rank: Frequent Contributor
timestamp: January 24, 2016, 09:30:58 pm
content: http://www.eurocircuits.com/PCB-design-guidelines#heatsinkpaste

author: wraper
author_rank: Unknown
timestamp: January 24, 2016, 10:21:34 pm
content: Quote from: jeroen74 on January 24, 2016, 09:30:58 pmThat is not thermal interface. That isheatsinkpaste which becomes solid and acts like a heatsink by itself.

author: jeroen74
author_rank: Frequent Contributor
timestamp: January 24, 2016, 10:45:16 pm
content: I don't see how a small flat surface acts as an efficient heatsink, so I always understood it to be a TIM to a real heatsink.Thissiteboth calls it heat transfer compound and heatsink paste. And readingthisappnote it seems you're right, but printable interface materials seem to exist as well which could solve the OP assembly problem.