Electronics Forum | Mon Aug 25 18:27:58 EDT 2008 | dyoungquist
Here is a post of the current profile. I have contacted our solder paste provider. They give a general lead free reflow profile guide. All that shows is genreral recomendations for temperature ranges and time ranges in each section of a typical
Electronics Forum | Fri Aug 29 10:37:44 EDT 2008 | gdzuber
Very interesting problem because it shows how systemic this kind of problem can be. So many variables, right? Firstly, discussions here are similar to everyone's postings, but there are some different observations. The manufacturer��s profile, we t
Electronics Forum | Wed Aug 27 14:38:20 EDT 2008 | rgduval
Does your paste provider recommend a TAL? For the leaded and lead-free pastes that we use, the manufacturer recommends 60 seconds above liquidous. I note that your profile shows the TAL as 30 seconds, which may not be sufficient. That said, tho
Electronics Forum | Tue Sep 02 15:29:36 EDT 2008 | bvdl
small pads like 0402 tend to get hot quite easily. looks like excessive heat is your problem here. pads are wetted, component leads are not. this means solder paste flux on top layer was exhausted before entering in reflow. your profile is the 'in-be
Electronics Forum | Sun Sep 28 17:14:53 EDT 2008 | ronsou
small pads like 0402 tend to get hot quite > easily. looks like excessive heat is your problem > here. pads are wetted, component leads are not. > this means solder paste flux on top layer was > exhausted before entering in reflow. your profile
Electronics Forum | Thu Aug 28 11:13:53 EDT 2008 | janz
Have you tried to run the same process but with diffrent solder paste manufacturer.? This give you information whether paste is ok. Try also print paste on the bare board and run through reflow oven. Check 2-3 boards. Is it the same places where i
Electronics Forum | Mon Dec 15 15:34:17 EST 2008 | dyoungquist
Sorry it has taken me so long to respond. I got pulled off onto other projects and was not able to work on the solution to the problen until recently. The solution we have come up with is to change from no-clean flux based solder paste to water sol
Electronics Forum | Wed Aug 27 15:48:05 EDT 2008 | grics
Again, our paste manufacturer specifies TAL to be 30-60 seconds. Out of curiousity, how would part placement cause de-wetting? I am fairly new to SMT so elaboration would be helpful... Thanks
Electronics Forum | Wed Aug 27 14:19:40 EDT 2008 | grics
Have you given this information to your paste manufacturer???(Profile, Pics of defects?) The profile seems to look ok(without knowing paste info...) I think the ramprate looks a little aggressive but it could be the scaling of the profile and the i
Electronics Forum | Mon Aug 25 15:40:58 EDT 2008 | dyoungquist
I am seeing poor quality solder joints, mostly on 0402 components. The problem is that while the pad on the pcb is getting fully wetted, the solder is not flowing up the sides of the 0402 component, i.e. the 0402 lead is somewhat de-wetting. The re
