Why do you guys suggest the gold bonding wires are incased in the epoxy?
If you are talking about the black epoxy part of the BGA chips like in the pic of the first post in this thread then it is not just a suggestion that the bond wires are
"incased" IN that black epoxy - it is a matter of FACT that, that is where the gold bond wires are
And how do I know that to be A FACT ?
Because when I was refining for "a living" I processed batches of those chips in batches ranging from as small as 5 pounds to as large as 30 pound & I can tell you for A FACT that the VAST MAJORITY of the gold in those BGA chips is the bond wires
"incased" in that black epoxy part of those chips
I’ve burnt the epoxy square and there was nothing in it.
Then you are ether doing something VERY wrong &/or you have no clue what you are even looking for
The ones of done they are right under a fiberglass sheet on the black epoxy
Those are NOT the bonding wires - those are copper leads that are sandwiched between the green fiber part of the chip & the black epoxy part of the chip - which are gold plated - the gold plating in those copper leads add up to VERY LITTLE of the gold that is in those chips
The VAST MAJORITY of the gold is the gold bond wires that are INCASED in the black epoxy
If you do not burn that black epoxy part if the chip to "complete" carbon &/or ash & crush them to "fine" powder to liberate the bond wires that is "incased" in the epoxy you are losing MOST of the gold
In other words - if all you do is only hit them with a torch - just enough to loosen the gold plated copper leads on the bottom of the black epoxy - so that you can "wipe" those leads off - it will take you about (plus/minus) 10 pounds of those chips to get about (plus/minus) 1 gram gold
On the other hand - if you burn the black epoxy to "complete" carbon/ash - & then crush them to "fine" powder to
"liberate" the bond wires you will get (plus/minus) right at 4 grams per pound - which means you will get right at (plus/minus) 40 grams per 10 pounds
I can say this for "a fact" because over the course of 10 years I probably processed 500 - 600 pounds of those chip in 5 - 30 pound batches at a time
Kurt