05/05/'99


Hello good people,
I have some OFF TOPIC questions on JTAG and boundary scan.

I have to look into the use of JTAG and boundary scan on a largish
production scale for here in Australia, now here comes the crunch-> A large
production run to us is in the order of 10000+ (Small in other parts of the
world).
I actually do question the purpose of such, as the original intonations
seem for JTAG seem to be just for connectivity testing, if so then as this
and component placement account for somewhere around the 90% of all
production errors. These errors can be found with optical inspection. So
what are the benefits of such and what is the cost?
Then there is the other nice things that JTAG offers, being able to
exercise the board, but one can ask the question is this beyond the need
for production test, I admit that JTAG device can help test a section that
is not JTAG, and create virtual test points. However what is the cost, both
in time and equipment?
I do understand that JTAG allows the production area to change tests
without effectively altering the test jig, and does allow for more tests,
and that the introduction costs seem to be small for connectivity testing.
But what are the benefits and cost; especially to employ logic function tests?

Dennis