How to re-ball a BGA...

[gszczesz]

bga template

I have an ATI Radeon Mobility chip 9700 that I need to re-ball...

I have an 850D heat gun, solder paste and a BGA stencil. I also have a 7-45X zoom microscope.

The stencil does not have a big-enough frame for the chip. When I put the stencil on the chip and start melting the solder paste with the air gun from the top, the paste tends to flow between the stencil and the IC and the solder balls tend not to stick to the pads.

If I put aluminum foil onto the stencil, then at least I can create little solder balls. The balls are a pain in the ass to transfer one-by-one onto the IC. The partially dried up flux does tend to keep them in place, but this really is a challenge to do.

If I cover the chip with paste and heat it with the heat gun from top, the solder tends to collect on a few pins, leaving the rest unballed.

Does anyone have a good technique for re-balling these huge IC's. The technique should NOT include a BGA machine, sending it out to be re-balled professionally, or any other cost-inhibitive method

Greg

 

[Pavel73]

bga heat gun

Russian guys do solderer cones of solder on contact platforms, and then warm up IC a drier before fusion of solder. Excellent spheres turn out.

 

[baraka42]

bga machine price

try this

wbr

 

[gszczesz]

bga templates

Unfortunetally the chip is too large for their technique, but the picture did clear up some stuff. thanks!

Greg

 

[sawwa7]

cell bga reballing

hi
Other ways of doing that and simpliest are taking chip out, putting new balls (you can buy flask of 10000 balls and they came in variety of sizes) and put them on chip in gel flux, heat up so they seat on chip, then put chip back in and heat up again
this would take even less than 30 minutes provided one have matrix for balls placement, and such matrixes are avialibable on market, or can be machined in cnc routers easly
also u can have a look here

**broken link removed**

Kind Regards

 

[gszczesz]

bga with heat gun

sawwa7,

I was looking into that solution but I couldn't find a place that sold the flask of solder balls (except for one that wanted to charge $1 a ball!!!)... Do you know where I can get the balls cheaply?

I did refine the process with the template to semi-work. I cut out the BGA template such that I could do a section of the chip at a time. The smaller template prevented excessive warping. I then applied the flux and put the template down and warmed it up with a solder iron. This dried up the flux a little bit and made it sticky, thus keeping the template on the chip. Then I continued as described in that jpeg... This seemed to work much better then what I did before, but overlapping sections is very difficult...

Greg

 

[baraka42]

reball with solder paste

@ Greg

have you try one by one line ? when you have allreadt cutted temlate.

i use 850 hot air gun and keep heat to 2.5 to 3 seting and air abt 2 to 3 setting. by low air ball not over laping .

i use this technics for cell phone bga reballing.

sorry for bad english.

wbr

 

[sawwa7]

german solder paste heat gun

hi gszczesz
have a look at this good article , i just found it and want to share
hope it'll be of some help to u and all colleagues who needs some info about rework BGA chips .
Kind Regards