Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BAKING MICRO BGA BOARDS AFTER REFLOW AND WASH

TONY

#27810

BAKING MICRO BGA BOARDS AFTER REFLOW AND WASH | 30 March, 2004

We are running double side micro bga boards and we were told to run one side, wash them, put them in the oven at 125c for 1 hour and putting them in the dry cabinet until we run the other side. Is this necessary? It is time consuming for us to wait that long to run the other side. Also after the second side with micro bgas, we put them in the oven again for an hour at the same temperature. I am trying to speed up the process. Please let me know your thoughts.

reply »

Ken

#27822

BAKING MICRO BGA BOARDS AFTER REFLOW AND WASH | 30 March, 2004

If speed is truly an issue, migrate to no-clean. However, this is not always an option.

Why bake after 1st smt pass? Because you are probably not drying completely under the BGA components, and/or you are pushing water into the parts/boards/ vias and having out-gassing or blistering/delamination/pop-corning issues.

Why bake after 2nd smt pass? If you leave water under the bga devices it can possibly affect functional test AND even in some cases promote dendritic growth of copper or silver migration. Last year I did a wash process evaluation that was driven due to silver migration under bga's. Bottom line, boards need to be "dry" beore test (dry is different things to different people)

Your heart is in the right place (speeding things up), just don't short-circuit the quality reasoning.

reply »

#27823

BAKING MICRO BGA BOARDS AFTER REFLOW AND WASH | 30 March, 2004

Tony

First, drying at 125*C for an hour is not going to do much drying. Heck, those boards are barely warm to the touch.

Second, tell us about: * Pitch of your uBGA * Solder paste flux * Cleaning process and agents

reply »

wgaffubar

#28006

BAKING MICRO BGA BOARDS AFTER REFLOW AND WASH | 12 April, 2004

Your wash unit should dry the boards well enough for you just take them and run them second pass within minutes of exiting the wash unit. We did it for years with no problem at all. If you must the hour at 125 will dry the wash water more than enough. To save time 30 minutes should work if you are just drying the wash water from the boards. I would bump the temp to about 150C for thirty minutes.

reply »

reflow oven profiler

PCB Soldering Tools