Electronics Forum | Wed Jun 10 11:21:04 EDT 1998 | Kelly Morris
Does anyone have any info./studies on what the percentage or PPM defect rates are for each part of the typical SMT process. Example: Screen Print = 45% of total defects Component Placement = 25% of total defects
Electronics Forum | Tue Mar 13 18:25:45 EST 2001 | slthomas
Anyone doing a print-dispense-place-reflow process? I've never heard of it being done this way before today. Don't know why, actually, as it sounds like a fairly friendly method provided the adhesives used are happy with a standard reflow profile.
Electronics Forum | Mon Jun 11 10:40:46 EDT 2007 | ramseyn
Jim, Another good resource would be Asymtek (www.asymtek.com) I have had a lot of luck with their dispense equipment for underfilling applications. They have run tests in the past using various methods for our company to determine what type of epoxy
Electronics Forum | Fri Apr 19 08:01:40 EDT 2002 | jnunns
We have been doing BGAs for about 3 years in house. We started off with an outside contractor and then brought it in. We are doing a variety of sizes from .05 to .03 pitch. We have 2D capability at print, but do not use it on any but the .03 pitch. T
Electronics Forum | Wed Apr 17 22:43:54 EDT 2002 | ianchan
what process is that? can kindly describe? is it that technology where bricks of solder are "ready made" deposit onto PCB pads thus eliminating the need to solder paste print/dispense by machine?
Electronics Forum | Fri Mar 16 15:52:22 EST 2001 | blnorman
We screen print epoxy adhesive, place components then run the board through our adhesive oven (2-5 min cure at 150�C). This is in addition to reflow.
Electronics Forum | Fri Mar 16 16:33:45 EST 2001 | davef
That's what we do also. It's the "print, dispense" sequence that's peculiar, but that's what you need to do if you are going to eliminate the glue cure cycle.
Electronics Forum | Tue Jan 22 09:48:09 EST 2008 | davef
Here's an article on flux / underfill compatibility http://ap.pennnet.com/articles/print_toc.cfm?p=36&v=16&i=6
Electronics Forum | Thu Apr 30 13:09:53 EDT 2009 | scottp
One factor I see missing is separation speed (or snap off speed). I've run experiments with different pastes where it was the biggest factor in standard deviation of print volume for small apertures.
Electronics Forum | Tue Jun 02 07:31:55 EDT 2009 | scottp
Early on when we started looking at BGAs we tried dipping. We've done it in production for a couple decades with flipchips. Dip fluxing BGAs worked fine in the lab but we ended up starting production with screen printed flux for cycle time reasons.
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