Electronics Forum | Thu Mar 22 16:02:37 EST 2001 | dblsixes
In the end, we may have to go to our customer to see if we can get Class 3 relief ... We actually did an experiment by adding a ceramic cap to the top of the part, using a thermal paste to improve the thermal connection. It didn't do much for us ..
Electronics Forum | Fri Oct 09 00:57:05 EDT 2009 | jjmag921612000
SteveO, I had personal experience with this using a Panasonic MPAV2B. It took a while, but I believe the end result was to have some additional "Z" travel to press the QFN into the paste. Also, the design of the paste on the ground was key to keep t
Electronics Forum | Wed Oct 21 08:06:06 EDT 2009 | scottp
I agree with Dave. If the device has a lot of power we'll put thermal vias between the solder deposits with annular rings of soldermask to keep solder out of the holes. We've never had to mess with placement pressure. We've been using QFNs for yea
Electronics Forum | Wed Jan 15 12:10:22 EST 2020 | emeto
Avillaro, I don't have hands on experience with Vapor Phase equipment, but my guess is that it will work better for thick boards like yours. Trying another chemistry is a logical move. May be it is worth trying the fixture for connector flatness as n
Electronics Forum | Thu Mar 22 15:44:50 EST 2001 | pteerink
I have a board with QFP240 plastic package exhibiting the same characteristics. Minimum heel fillet that doesn't change with stencil mods, paste change, profile change etc ( I am working to class 2, though, so my pass spec, although they are not pret
Electronics Forum | Thu Mar 22 15:45:20 EST 2001 | pteerink
I have a board with QFP240 plastic package exhibiting the same characteristics. Minimum heel fillet that doesn't change with stencil mods, paste change, profile change etc ( I am working to class 2, though, so mine pass spec, although they are not pr
Electronics Forum | Mon Mar 26 20:55:16 EST 2001 | davef
Two things: 1 IPC pad calculator is an excellent resource for you and your board layout staff. Consider that working together with the calculator may allow you both an opportunity to balance your interests. 2 It's unlikely that the ceramic parts h
Electronics Forum | Tue Mar 27 02:57:32 EST 2001 | Ken S.
Have you a reflow oven that has upper and lower heaters? Have you a reflow oven that uses hot air as well as elements to control the transfer of heat to various areas? If yes to these, I would suggest increased air flow or change in direction of
Electronics Forum | Tue Jan 14 11:39:51 EST 2020 | avillaro2020
Thanks Robl. I’ve contacted samtec followed their advice but ended up empty handed. Originally my stencil thickness is 6 mils, samtec stressed the need for the paste and charge to have good contact but this is challenged by the inherent charge non-co
Electronics Forum | Tue Jan 14 17:22:16 EST 2020 | emeto
Avillaro, would you say that vapor phase process was selected, because the boards are so thick and heavy? I would assume so. Have you ever tried to run them through reflow oven? To understand better your challenge, we need to understand the setup be