They are changing their tune, Dave :) One says: " Metalization is hiding all the lower levels. Looks like a device with just 6 transistors." Another responds: "So it would be a *transistor* array, not a gate array then. If so, then I’m confused as to why it would need so many pins if there are only 6 transistors. Unless it was a prototyping part where all the transistors were individually made accessible." (I'm positing with them # pins is because possibly they're gates) On 8/21/2022 12:50 PM, Dave McGuire via vcf-midatlantic wrote:
Yes, but we should be able to determine everything, or almost everything we need to know from that layer. We'd need better and higher-resolution photos.
-Dave
On 8/21/22 12:48, Douglas Crawford via vcf-midatlantic wrote:
Ah, now we are getting somewhere. We can only guess then, from the remaining metalization layer correct? Educated guess?
On 8/21/2022 12:43 PM, Dave McGuire via vcf-midatlantic wrote:
On 8/21/22 12:39, Douglas Crawford via vcf-midatlantic wrote:
These are the transistors? https://imgur.com/aLpqVpE
I'd need to look more closely, but those appear to be clusters of transistors, six of them. They are likely gates.
I got one additional response from another designer: "Looks like some kind of gate array with only the metalization layer being clearly visible. I worked on alot of these in the late 70's. I have no explanation for the bonding pad structures."
Agreed; this has either had its passivation layer removed, or it had never been applied. I suspect the latter, as it would've been removed with acid, and there isn't so much as a trace of debris from that.
-Dave