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Old 8th Apr 2021, 7:29 pm   #158
ortek_service
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Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
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Default Re: The Transam Triton Personal Computer

Well that does appear quite strange, in that there doesn't appear to be any pads on the underside of the chip/die.
And that there's just a 'via' hole thorough it from the top surface.

So it seems like something conductive is dropped down the holes to the substrate below - as you can see the circular marks on the pads of that (which I presume aren't holes through the substrate itself?)

And I presume the holes in the die aren't just filled with the covering clear glob-top (Although maybe they are effectively plated all the way down, and only the bottom part attaches to the substrate - possibly be just being forced into some conductive epoxy on the pads - or possibly solder paste and reflowed).
As I can't see it being very easy to force solder or conductive epoxy down from the top of the chip.
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