Electronics Forum | Mon Apr 01 10:24:29 EDT 2013 | emeto
First check the profile. I would go with linear profile and smoother increase of temperature. Usually you will get tombstones when you have too aggressive profile. My next step will be to redesign the stencil.
Electronics Forum | Fri Feb 13 11:46:23 EST 2004 | Jack
Is your customer trying to reduce voiding? If the device is using Sn90 / Pb10 and the paste is Sn63/Pb37 the board will melt first. However, if both solders are 183C eutectic, it's a tossup? PCB design, copper weight, bga type (pbga, micro bga, Tbg
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.
Electronics Forum | Fri Mar 22 18:16:44 EDT 2013 | vpham
We are trying to use this high-temp solder paste due to a very special process, but we run into tombstones on chip caps, 0402 and 0603. We don't have this problem if we use regular SAC305 solder paste. If you have experience with this type of solde
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
Electronics Forum | Mon Apr 01 17:20:45 EDT 2013 | davef
In thinking about troubleshooting tombstoning {TS} defects, seek balance: * Pads the same size * Same amount of paste on each pad * Component placed with the same amount of contact on each pad * Heating the same on each pad, no via connection to a gr
Electronics Forum | Mon May 09 16:44:33 EDT 2011 | dcell_1t
Hi, We have been struggling with an issue of non wetting on a QFP (Renesas - 256, Sn90Pb10) but the issue "desapears" sometimes for a while and then back again suddenly. This is the scenario: Component: QFP 256 / Renesas / Sn90Pb10 / 0.5 mm pitch S
Electronics Forum | Thu Nov 14 11:08:29 EST 2002 | bcceng
Kevin, I have done the following process to a similar problem: 1. Plug holes (even to both sides of the board) 2. Clean any flux left on the surface, especially on bottom side. 3. Apply Kapton tape to the bottom side, you mite want to apply 3 layers
Electronics Forum | Fri Mar 19 11:48:06 EST 2004 | Ken
This is the dilema during this transition period. Here is a tip: If you see typcial solder joints on a lead free process, but only on one component type....it probably has a significant quantity of lead in it (ex. Sn90/Pb10...and so on) If using T
| 1 |
winsouce.jpg)