Electronics Forum: dewetting and ag (Page 1 of 5)

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Fri Mar 06 16:17:38 EST 2009 | aj

whats your board finish?

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Fri Mar 06 10:46:35 EST 2009 | davef

First, we agree with Loco that your QFP is nonwetting, rather than dewetting. Your sceen-shots look like ol' timey SnPb paste recipes. Turn-up the heaterometer dial. Second, on nitrogen: * We kinda think your O2 needs to be around 100ppm with 99.99%

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Fri Mar 06 10:50:21 EST 2009 | fountain42

Just my opinion but it look's like your doing a great job. i would try another paste. I'm somewhat lucky that we get to use OA's. If your stuck using the no-cleans they are so tempermental. (The nitrogen is making up for the poor paste) Your de-wetti

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Fri Mar 06 02:47:15 EST 2009 | lococost

Have you tried higher peaktemp? I saw the QFP is sn90pb10, This has a liquidus of 268 - 302 C. A good paste should be able to handle 230C (or more), of course you would need to check your other components peak temp.

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Fri Mar 06 11:01:53 EST 2009 | dyoungquist

I have attached a pdf version of an article that explains the basics of a nitrogen atmosphere when soldering. It gives some basic guidlines as to when one may want to use nitrogen and what it can and can not accomplish. FYI- I did not write that ar

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Thu Mar 05 11:53:09 EST 2009 | dcell_1t

Hello to all. for certain time, we have been struggling with some issues on a PCB where have tombstoning on 0402 components (due to pad design) and dewetting in qfp256 0.5 mil pitch (discussed on another threads on this forum) component, we have pro

0402 tombstoning and dewetting on QFP256 trade-off

Electronics Forum | Thu Mar 12 06:37:48 EDT 2009 | gregoryyork

I agree you are too cold for the profile get it up to 230C and possibly allow it to dwell a little longer in preheat as opposed to pushing up the reflow zone only. Sn90/Pb10 melts at 220C so 2C hotter than your profile so you are reliant on it alloyi

Ag-plated LED dipping - high level of Cu and Ag

Electronics Forum | Tue Aug 14 23:58:19 EDT 2001 | Glen Brian

We are using the new auto-dipping machine for LED solder dipping and dragging. The flux is water-soluble flux and the solder is 63/37 at 250 deg. C. Two weeks ago we exchanged the pot with new 63/37 solder. About a week, we found that the high level

Ag-plated LED dipping - high level of Cu and Ag

Electronics Forum | Wed Aug 15 16:04:23 EDT 2001 | davef

First, responding to your question � Several things on copper dissolution in solder are: * A 50um copper wire will dissolve in 60Sn / 40Pb solder at: - 200�C solder in 55 seconds; - 250�C solder in 20 seconds; - 300�C solder in 5 seconds; - 350�C so

Silver Epoxy and CEM3

Electronics Forum | Wed Aug 26 12:02:23 EDT 1998 | Steve Joy

Does anyone have any experience they are willing to share on Ag epoxy used as a copper through hole plating replacement? Was CEM3 used? What are the limitations? Thanks, Steve

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