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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA via in pad

Views: 1221

Shane

#48396

BGA via in pad | 14 March, 2007

I have a customer that designed a fine pitch BGA into a board, and has put small vias in the middle of each pad on the PCB. Anyone have any ideas on how I can prevent the solder from the BGA from flowing through the vias and causing voids or no contacts on the BGA solder joints?

reply »

Pete

#48426

BGA via in pad | 15 March, 2007

We had a customer do a similar thing. We notified our customer and educated them on what was happening. We were instructed to try one and report on the results, as the vias were supposed to be filled (and weren't). We pasted and reflowed and as suspected, the paste did wick into the vias and we were not able to produce acceptable results. Board was re-fabricated with filled vias and all was well.

reply »

#48462

BGA via in pad | 16 March, 2007

Ask the board fabricator to: * Fill the vias with resin. * Then metalize and copper plate the filled via along with the pad. * Then plate with solderability protection.

This results in what appears to be a solid pad.

For more, look here: http://www.enthone.com/docs/IPCfall2003.pdf

We have no relationship, nor receive benefit from the company referenced above.

reply »

Peter W

#48595

BGA via in pad | 23 March, 2007

Hello,

those plated and solderable via in pads have two critical points: 1. We have discovered that _sometimes_ the plating seems not to be perfect, as extreme voiding is visible in tha bga solder ball 2. The detection of some defects by AXI is limited or even prevented by a via in pad situation. This is no issue for standard tests such as bridge but some special algorithms have problems with this.

Peter

reply »

PCB Soldering Tools

Real-time PCB X-ray Inspection System