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

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reballing | 12 January, 2004

who has the step by step how to reball a Ceramic BGA this is a CBGA 50 mil pitch 29 by 29 mm size

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reballing | 12 January, 2004

High temp balls (spheres for you PC types)

They are non-eutectic balls. Do you have a reballer or stencil setup? If one device...may not be cost effective, but if many you can usually send back the the IC house for re-ball. There are only a handful of BGA foundries that do this work. Your IC supplier can fill in the details.

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reballing | 13 January, 2004

A small benchtop system uses a mask, tooled for your part, to arrange the solder spheres onto the BGA, after it has had the excess solder heat-vacuumed off and a new layer of flux applied. The spheres are poured into the cavity, excess decanted off. Then the part is placed on a small mini-oven suited for taking the BGA up thru the reflow profile and back down. Send me an email to discuss where to get this equipment.

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reballing | 13 January, 2004

I believe that solder paste will need to be applied to this part. I have re-balled these in the past in a low volume situation and here is what I did and there appears to be no adverse effects to the component.

Get a stencil (I use 8 mil for .032" high temp balls) for this part from someone like minimicro stencil, They may also provide masks for applying solder balls. You may need to fab some sort of BGA holder for the print operation. Print the pads on the BGA and then reflow at the minimum temp to just get it melted, about 190 C for 63/37 alloy paste.

Then you can use a mask as noted previous to place over the BGA. You will want to first apply flux to pads prior to placing the mask over the part. Pour in the solder balls and then reflow again at a temp just hot enough to reflow the balls to the solder you have reflowed onto the pads. You do not want to reflow the High temp balls that are used for CBGAs during this operation.

Please note the additional reflow cycle in this operation. This may or may not affect the reliability of this part. This is the reason for the minimum temps in the reflow cycles.

Hope this helps


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reballing | 13 January, 2004

Have you looked at solderquik? Winslow Automation sells them. I've had good luck with them. They are bga preforms with the balls on a water soluble paper.

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reballing | 22 January, 2004

CBGA devices are a bit trickier to reball than run of the mil plastic devices. Once assemblied they are a bit like a sandwich when fitted to a PCB. From top to bottom it goes BGA device - Eutectic solder - High temp solder ball - eutectic solder - PCB. So to reball it to the same spec that it was made, you need to attach a high temp ball to the device using eutectic solder. During manufacture only the eutectic solder is supposed to reflow, leaving the high temp ball intact thus giving you the high stand off you need for thermal management. So reballing CGBA's is a nightmare. My advice, give up now before its too late!!! The other issue to consider is "Do you really want to". If you check the data sheet for the device in questeion, you will probably find the line "maximum number of reflows = 2", or similar. Which means that they will not warrenty the device if you reball it. Build = 1, Remove = 2, reball = 3, replace = 4 double the specified minimum. So unless the device is unique or prohibitivly expensive to replace I would leave well alone.

Nick, Coopertools UK

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