Help in designing a BGA prism inspection system

Thread Starter

microcontrollerguy

Joined Sep 19, 2021
4
i'm looking to create a BGA (and qfn) inspection camera, for inspecting BGA solder balls under the chip. Looking at commercial options, they seem to start at around 900$, and go up greatly from there. The prism modules for these are around 250$ and up. However, i think that there is probably not that much that is "special" about these prisms. I found a non camera version that is now discontinued, but seemed to retail for around 50$, called the PRIBALL. Link 1 Link 2. Here is a link to a paper discussing these systems. Paper.

Here is a rough sketch of how the system would probably work. Came from a EEVBlog thread, which has more detail on the PRIBALL Here.
404A7FDD-573E-4667-AF6B-66D4A997DD95.jpeg

looking at the commercial BGA-100 and BGA-300 inspection systems, they seem to be just "normal" camera, with their custom adapter screwed on the end. Likely my system will be similar, with a 3D printed c-mount adapter for the prism, with an adjustable zoom lense in-between?

the first task is finding a prism. I will admit that i know very little about these, or the manufacturers of them. I am yet to find a prism as pictured below for sale by itself, for a "reasonable" price. Shown Below is one such special inspection prism, specifically the PR-1 90 Degree Viewing Prism Tip, which costs 350$.

Capture.PNG

Has anyone DIYed this before? i have looked for other DIY projects but haven't found any, so perhaps this is more difficult to accomplish than i thought. Does anyone know where i could find suitable prisms for sale for "reasonable" prices (i think a sub 50$ prism would suffice?). Perhaps using a small right angle prism "triangle shaped" which seem to be everywhere would be good enough?
 

MisterBill2

Joined Jan 23, 2018
18,508
The only check that I am aware of is an x-ray inspection. That will usually show solder balls that have not connected. Seeing the balls not close to the edge does not seem possible.
 

Thread Starter

microcontrollerguy

Joined Sep 19, 2021
4
The only check that I am aware of is an x-ray inspection. That will usually show solder balls that have not connected. Seeing the balls not close to the edge does not seem possible.
It is possible, but no it's not as good as x-ray, but it can check for shorts allignment etc. Good for basic checks like that. Can't see balls in the middle (if fully soldered), but will see if they are shorted, and can see outside balls soldered or not.

Here is a video demonstrating one of these systems:

 
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