Electronics Forum | Tue Oct 03 17:44:23 EDT 2006 | SWAG
I am trying to get a CyberOptics SE200 on line. Does anybody have any idea why the SMEMA interface is always telling the downstream machine that a board is available? It will not switch off no matter what running condition the machine is in - even
Electronics Forum | Wed Oct 04 11:36:06 EDT 2006 | flipit
Hi, Anyone ever have an issue with stray capacitance when using no clean solder paste. We are having a timing problem on one product. The problem goes away when we clean the assemblies. We use a no clean process normally. These assemblies worked
Electronics Forum | Wed Oct 04 13:58:38 EDT 2006 | cw
hi Dave.F and All, I need to reflow SCA solder balls on Sn/Pb paste, i get a pretty OK solder wetting and collapse apperance, however, i am seeing voids everywhere, some of them is greater than 25-30%, which has exceeded IPC standard. Please advise.
Electronics Forum | Wed Oct 04 14:14:49 EDT 2006 | russ
Change mfgrs of paste OR better yet use pbfree paste, If you are collapsing the balls on the BGA then you are possibly overheating the paste/flux quite a bit. most lead pastes do not like much more than 230 C. I am assuming that you have a decent p
Electronics Forum | Wed Oct 04 14:18:05 EDT 2006 | C.K. the Flip
The main cause of voids is your flux out-gassing during reflow. Try a little "knee" or slight soak in your thermal profile to dry out the volatiles a bit. Typical soak ranges from 130 deg. C to 170 deg. C for around 30-90 seconds.
Electronics Forum | Wed Oct 04 14:48:49 EDT 2006 | cw
My soak at 150C - 180C for approx. 85sec to 100sec. I believe this is sufficient. I can't change my paste because customer wants to use SnPb paste with SAC solder balls. They claimed that they have sucessful result with other CM. I need to know if
Electronics Forum | Wed Oct 04 16:14:17 EDT 2006 | inds
what is your peak temp.. if you try to go too high say 225-230 deg C there is a fair chance of seeing voids.. depending on your ball size and paste volume you can get a good collapse at temps below 225deg C...
Electronics Forum | Wed Oct 04 16:24:48 EDT 2006 | russ
try Alpha OM5100 this is a noclean paste that we use and have done the same thing you are now, reflowing pbfree with pb paste, we run to max temp of 230C with this paste and use a straight ramp with no soak profile is about 4 mins long from ambiant
Electronics Forum | Thu Oct 05 16:12:09 EDT 2006 | Mario Scalzo, SMT CPE
* Try 1.5C / sec from RT to 165C * Hot soak at 165-175C for up to 2 minutes (I'd start with 60 seconds flat soak.) * 60-90 seconds TAL (I's start with 60) * 230-240C Peak. Thanks, Mario
Electronics Forum | Fri Oct 06 15:43:33 EDT 2006 | Mario Scalzo, SMT CPE
What I usually do is keep the peak temperature about 5-10 deg C below the peak temperature of my lowest rated component, then set everything else up around that. Worse case scenario is to just extend the time above liquidus (TAL) in 5 second increme
