Help in designing a BGA prism inspection system

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$, called the PRIBALL. Link 1 Link 2. Here is a link to a paper discussing these systems. Paper. Here is a rough sketch of how the system would probably work. Came from a EEVBlog thread, which has more detail on the PRIBALL Here. looking at the commercial BGA-100 and BGA-300 inspection systems, they seem to be just "normal" camera, with their custom adapter screwed on the end. Likely my system will be similar, with a 3D printed c-mount adapter for the prism, with an adjustable zoom lense in-between? the first task is finding a prism. I will admit that i know very little about these, or the manufacturers of them. I am yet to find a prism as pictured below for sale by itself, for a "reasonable" price. Shown Below is one such special inspection prism, specifically the PR-1 90 Degree Viewing Prism Tip, which costs 350$.

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
14,244
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.