Indium Corporation
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Theory of “Ball Drop” Sphere Placement

Monday, March 23, 2009 by Jim Hisert [Jim Hisert]
After transferring flux, align the stencil

After transferring flux, align the stencil

Setup print parameters to minimize doubles and missing solder spheres

Setup print parameters to minimize doubles and missing solder spheres

Remove stencil, substrate/die should be ready for inspection and reflow

Remove stencil, substrate/die should be ready for inspection and reflow

 

 

Spheres can be placed by many methods.  Depending on the scale of production, spheres are placed by printing, vacuum transfer, jetting, pick and place nozzles, and even tweezers.  These methods are used to align solder spheres on substrates or die for subsequent soldering.

 

Companies which currently make ‘ball drop’ attachments for standard printing equipment include DEK and Speedline.  There are also specialized machines that perform this stencil printing operation as well as prior flux transfer steps.

 

If you are interested in learning more about solder spheres and the way they are applied Click Here or call us at (315) 853-4900

 

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Comments for Theory of “Ball Drop” Sphere Placement

Saturday, August 8, 2009 by abdullah:
Dear Sir: First of all please accept my thanks for your good tips which are given in your site, secoundly would you please let me know a practical home-made way of making BGA spheres. Best Regards: Abdullah Savas
Wednesday, August 12, 2009 by Jim H.:
The best way to mount spheres by hand is to buy a set of mini hand stencils. One stencil should be designed for printing the flux on the pads, and a second stencil with a standoff can be used to print spheres. A razor can be used to print the flux and a fine artist’s paintbrush is good for getting the spheres to drop into the other stencil. A good flux is important to open up your reflow process window since it may not be as controlled.
Saturday, August 15, 2009 by abdullah:
Dear Sir: I rally appreciate your nice reply and according to your command ,I have done that way but some spheres are small and some bigger that say 0.76mm can you please let me know how can I get homogenouse ones i.e. all in 0.76mm form. once again please accept my best regards: Abdullah Savas
Tuesday, August 18, 2009 by Jim H:
Hi Abdullah, My mistake, I misunderstood you the first time. I thought you wanted to place spheres by hand, but it sounds like you want to make spheres by hand. One idea would be to make many spheres using the process you have set up, and then filter out the ones that are too big or too small. It is quite normal to use classification to compensate for variation in diameter. If you purchase spheres, you’ll have the luxury of a .025mm diameter tolerance standard, with tighter tolerances available by request. I hope this helps, ~Jim

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