BARRY,

I HAVE HAD QUITE A BIT OF EXPERIENCE WITH BOARDS WITH "VIP".I HOPE THESE
SUGGESTIONS WILL HELP.

FIRST THING YOU SHOULD DO IS SPEC THAT THE VIAS THAT ARE LOCATED IN SMD PADS
BE AN 8 MIL FINISHED HOLE +2-0.
SOMETIMES IT MAY BE DIFFICULT TO FIND A BOARD HOUSE TO STAY WITHIN THESE
GUIDELINES,BUT THIS SEEMS TO WORK VERY WELL.

I WOULD ALSO SUGGEST THAT YOU OPEN THE APERATURES IN THE STENCIL BY 2 MIL S
ON THESE PADS.YOUR BEST BET WOULD BE TO DESIGN THIS RIGHT INTO THE PART IN
THE COMPONENT LIBRARY,IF YOU CAN.

IF YOU OPEN THE APERATURES IN THE STENCIL TJIS WILL HELP TO COMPENSATE FOR
THE SOLDER PASTE MIGRATION INTO THE VIA.
ALSO ,TRY AND LOCATE THE HOLE RIGHT UNDER THE LEAD AS TO TRY TO DECREASE THE
AMOUNT OF SOLDER LOST IN THE HOLE.

* NOTE THAT IF YOU ARE USING AND AUTOMATED OPTICAL INSECTION PROCESS YOU MAY
HAVE PROBLEMS WITH FALSE FLAGS ON THE PINS WITH THE VIAS BECAUSE THEY MAY
APPEAR TO BE A LITTLE LIGHT ON SOLDER.IN MOST CASES THERE IS STILL PLENTY OF
SOLDER TO FORM AN ACCEPTABLE AND RELIABLE FILLET.

I HOPE THIS WILL HELP,PLEASE REPLY AN LET US KNOW YOUR RESULTS.

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