Electronics Forum | Wed Jul 09 19:05:06 EDT 2003 | randywomack
LOZ. Under-cured or out-of-spec(sloppily) applied resist is realistic. What other physics: Shiny resist surface is more prone to balls then matte finish. How about an operator eating fish & chips before handling the boards. Don't laugh... ... saw th
Electronics Forum | Wed Jul 09 13:48:03 EDT 2003 | russ
Sam, You may want to be careful with your analisys, reducing paste volume also reduces flux volume. Flux is there to promote and aid in wetting. by reducing flux you may have initiated the poor wetting yourself with the experiment. Just anothe
Electronics Forum | Thu Jul 31 15:29:25 EDT 2003 | bcceng
A couple of things you can look into 1. The proper bottom pre-heat of board. If you are applying only direct hot air to BGA without preheating can cause BGA's to warp and collapse un-even. 2. Moisture on you BGA's. If BGA's were not properly packa
Electronics Forum | Tue Aug 05 17:19:55 EDT 2003 | csimfgeng
Another variable is whether the ground pads have proper thermal reliefs. If the pad has solid ground plane around the perimeter, the heat being applied will quickly dissipate to the surrounding metal. A proper relief of the pad will prevent the hea
Electronics Forum | Fri Aug 15 19:52:38 EDT 2003 | Jay
Dave, By Mishandled OSP i meant that it had been touched by bare hands (including pads). Its not like I want to or I donot want to bake these boards. Its just that i want to be sure that the boards will be good to use. And I like your idea to apply
Electronics Forum | Thu Aug 21 18:36:32 EDT 2003 | paulm
Hi Dave and Justin, Thanks for the advice. Dave you mentioned you "smush" your bga's. What type of machine are you placing then with it? Is the additional pressure to smush them machine or manually applied? Also, the 0.004" variance we are being
Electronics Forum | Fri Sep 05 16:36:50 EDT 2003 | mleber
We handle this issue by adding a .1, .2 etc after the existing rev. Ex. Rev is A - we do an internal Rev changing an item and it goes to Rev A.1 - Basically you are building a Rev A with that ECO applied to it. It works well but you need to pay atte
Electronics Forum | Thu Oct 16 13:36:01 EDT 2003 | russ
The color does mean something, If you know the manufacturer their spec sheet will tell you. The three and 4 digit only applies to larger resistors, There are 1% 0603 that have only 3 digits. You may want to just call them all 5%. Russ
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 | Tue Jan 13 15:16:12 EST 2004 | drewhmi
A small benchtop system uses a mask, tooled for your part, to arrange the solder spheres onto the BGA, after it has had the excess solder heat-vacuumed off and a new layer of flux applied. The spheres are poured into the cavity, excess decanted off.
