PCB Expansion (Y & X-axis)

Subscribe to Thread

Hi! I'm facing a strange problem where PCB expanded in X & ... - Sep 25, 2005 by

Not that this actually happens anymore, but could it possibl... - Sep 26, 2005 by Avalancher

Make sure the stencil lined up perfectly in the middle all a... - Sep 26, 2005 by Stephen

duplicate post, sorry ... - Sep 26, 2005 by Steve Thomas

"Note: nothing changed to the process, the problem come out ... - Sep 26, 2005 by Steve Thomas

#36824

PCB Expansion (Y & X-axis) | 25 September, 2005

Hi! I'm facing a strange problem where PCB expanded in X & Y-axis after bottom-side reflow. When the PCB send for Top-side printing process, it is abvious that the printing alignment on the PCB's pads are out.

With the problem mentioned above, I am facing multiple 0402 capacitor tombstoning.

Has anyone got any idea about how to solve this problem?

Note: nothing changed to the process, the problem come out of sudden.

This message was posted via the Electronics Forum @

reply »

Avalancher

#36833

PCB Expansion (Y & X-axis) | 26 September, 2005

Not that this actually happens anymore, but could it possibly be moisture in the PCB? Have you tried baking one or two for a couple of hours then run to see if it repeats?

reply »

Stephen

#36834

PCB Expansion (Y & X-axis) | 26 September, 2005

Make sure the stencil lined up perfectly in the middle all along the width of the board. Everytime someone has told me that a stencil doesn't match the board, they were not critical enough on alignment. Usually they would say one corner is perfect but the other side was not. When I checked the "perfect" corner had a minute amount of skew.

Try printing some top sides before reflowing the bottom.

Have you measured the board before and after? What kind of percentage are we talking about?

reply »

Steve Thomas

#36837

PCB Expansion (Y & X-axis) | 26 September, 2005

duplicate post, sorry

reply »

Steve Thomas

#36839

PCB Expansion (Y & X-axis) | 26 September, 2005

"Note: nothing changed to the process, the problem come out of sudden."