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Electronics Forum | Tue Aug 26 21:20:58 EDT 2003 | iman
You may check with the TDS of respective "active parts" IC manufacturers for their recommended no. of thermal cycles permissible in the reflow process. Last I checked 3 cycles for our RF-apps IC was still allowed. For 48pin-QFPs this can be allowed
Electronics Forum | Thu Sep 04 16:44:19 EDT 2003 | mleber
We are a military contractor running mixed technology CCA's. We currently "map" all defects off reflow and wave by indicating the defect on a map (plot from gerber) then passing it on to rework. The map is used for SPC data as well as overall perform
Electronics Forum | Thu Oct 02 11:09:57 EDT 2003 | James
Yes we verify every reel by some other operator. We hardly make mistakes now, due to the fact that they have to also write the initials of who verified it. There used to be many mistakes due to wrong reels, but now it is slim to none. It is better t
Electronics Forum | Tue Nov 04 16:32:22 EST 2003 | Marc
Marc, I agree with Dennis. Your best method is to apply solder mask over the pads, then install the BGA. You can also remove the balls or completely remove the pads, but it take a skill person to do it. We do all that type precise rework in Southern
Electronics Forum | Wed Feb 18 12:13:50 EST 2004 | babe
my experience tells me you should have no problem. However please remove the flux residues from the board. Unless of course this is a product that is inexpensive and you don't care about degradation/flux migration etc. In example an electronic toy. T
Electronics Forum | Wed Apr 14 07:59:54 EDT 2004 | arcandspark
Makes a lot of sense, thanks for the excellent input. The peak temp I am running fo our pb free (238C and approx. 90 seconds above 183 C)is the recommended profile from T.I and also the solder paste manufacture. Not sure exactly what the melting temp
Electronics Forum | Sun Apr 18 06:49:10 EDT 2004 | Nick Prince
You might like to check ou the SSTC at the National Physical labs, in the UK. They have done a lot of research in mixing PB and PB free alloys. Its high Science stuff but intelligable. The upshot seems to be that if you mix PB and PB Free alloys th
Electronics Forum | Tue Apr 13 08:19:52 EDT 2004 | arcandspark
The PCB's we are seeing the voids on are made of some material called Thermount, not FR4. The pads are very easily pulled off if any touch up or rework is done. The voids I am seeing are (hugh) 50% to 75% of the Solder Ball volume. The last new batch
Electronics Forum | Wed Apr 28 12:10:14 EDT 2004 | paul_bmc
Are your solder balls after reflow a perfect sphere or are they oblong, like chushed. I know a heavy bga or incorrect reflow profile could cause bridging. Also too much flux paste. Sometimes what we do is brush the flux paste onto the pcb pads inst
Electronics Forum | Wed Apr 28 15:08:10 EDT 2004 | russ
This could be a long shot but here goes. I have found that if flux is applied in excess that it will actually "move the solderballs" during reflow. I have actually seen where the balls are completely outside the package and oviously there are short
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