Electronics Forum | Fri Sep 07 12:19:20 EDT 2007 | guqing
We are having problem to develop lead-free (SAC305) reflow profile for big SMT electrolytic caps. The delta T of the joint of the cap with the rest of the board is too big to fit in the tighter lead-free window. Any suggestions regarding the total pr
Electronics Forum | Wed Jan 28 20:26:32 EST 2004 | Vinny
Hi Guys, Really need your help to suggest how to tackle this situation.
Electronics Forum | Mon Jan 26 04:13:48 EST 2004 | patthemack
First of all, did you profile this board with a mole, such as a KIC? Is the solder flowing, or just not wetting to the part or pad? I work with RF boards as well, but the main problem is tombstoning due to the ground plane side being larger because o
Electronics Forum | Wed Jan 28 20:58:16 EST 2004 | davef
Vinny: From a thermal standpoint, your choices are: * Get your customer to design thermal relief in the board. * Set your thermal recipe to assure that the grounded pad reaches reflow temperature. This may require a long soak at a single temperature
Electronics Forum | Thu Jan 29 18:01:20 EST 2004 | davef
Rethinking to Ramp / Soak: Yano, staying with ramp might not be all that bad after all, just decrease the ramp / slow-down the conveyor.
Electronics Forum | Mon Jan 26 03:45:37 EST 2004 | Vinny
Hi All, We are producing a veriety of RF related PCBAs in which we see Unsolder/Mislaigned on a regular basis. In these baords usually one of the pad is connected to a signal trace and the other pad is connected to very huge ground plane. This gro
Electronics Forum | Mon Jan 26 21:10:36 EST 2004 | Vinny
I have done acurate profiling which meets the solder paste specifications. The point I am trying to highlight here is also due to the ground plane side being much larger causing the tombstone defect. I have even tried doing a linear profile, it hel
Electronics Forum | Thu Jan 29 06:58:40 EST 2004 | davef
Ramp / Soak: Tombstoning is occuring during reflow. You need to get more heat into the ground plane. Obviously a ramp aint gettin' it done. Further, without intending to disrespect your internal discussion, if a linear profile improved the situati
Electronics Forum | Thu Jan 29 00:10:17 EST 2004 | Vinny
Hi Dave, Thanks for your reply. I have tried getting the design changed from the customer but they cannot provide thermal relief as this changes the RF performance and they cannot afford to do that. As for profile it does reach the reflow tempera
Electronics Forum | Tue Feb 10 15:13:06 EST 2004 | patthemack
Hey Vinny, Sorry I haven't looked at this for a while. 3 things to try: Tombstoning- The ground plane side is larger because the solder mask allows for a little slop at the board shop (clearance around a pad of a few mils). Since there is not a defi
