mirco bga stencil opening

I have printed and placed similar devices in high volume with exactly this spec for a couple of years with no problems, are you using laser cut stencils and what type of solder paste are you using? and what is the end use of the product as it may need underfill depending on application even when your process is with out cracking.

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I have printed and placed similar devices in high volume with exactly this spec for a couple of years with no problems, are you using laser cut stencils and what type of solder paste are you using? and what is the end use of the product as it may need underfill depending on application even when your process is with out cracking. What about your reflow profile are you using RSS RTS have you checked with thermocouples under BGA device

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We have used a laser cut stencil 0.15mm (0.006") thick with 0.3mm (0.012") square apertures radiused in the corners 0.06mm (0.0025") to aid paste release. This approach with the (type 3) paste we use has proven successful on thousands of devices placed over the last 18 months or so. This additional past volume gives a little more compliance in the soldered joint and we have had no failures of the joints themselves.

Some questions:

1. Where are the cracks you are seeing occurring, at the ball/PCB interface, the ball/device interface or in the bulk solder?

2. Is the device located on an area of the circuit that is subjected to flexure during ICT?

3. What kind of solder paste are you using and what is your reflow profile?

Regards,

Peter Barton

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CK, If joints have been validated prior to ICT (under BGA Scope), more often than not repeatable joint fractures are due to undo stress being placed on the component during ICT test. Verify ICT probes and fixture. If after proving out fixture/pin compliance, next look at the land finish. If gold, embrittlement could be occuring. First step would be to inspect/validate the finish per IPC standards. Your PCB supplier should be able to help you with this. Any additional questions, please feel free to contact me. Scott

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Dear colleagues. I ask you to prompt me about necessity of drawing pastes through a stensil at the soldering micro BGA with step between leeds 1 mm and 0,8 mm or uses only a flux for this purpose. And what most suitable paste for the soldering of such components? What sizes of apertures on a stensil?Where it is possible to find the literature under the soldering micro BGA and Flip Chips?

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