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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 7 Dec 1998 15:26:04 -0500 |
Content-Type: | text/plain |
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> On Mon, 7 Dec 1998, CONKNET wrote:
>
> > Successful test of .030 micro-bga's on traditional (bed of nails / grid)
> > equipment is reliable and not too difficult to achieve. It does not require
> > "double density" grids. It does require good fixture design. Test of 30 mil
> > BGA's typically requires 3.75 inch multi-plate fixtures with 12 or 16 mil
> > piano wire pins. Some care needs to be given to the Z axis load created by
> > the test pins on thin boards. Although Pin Tilt can approach or exceed 1
> > inch, the pad size on BGA's make a big target relative to 15 mil QFP device,
> > so targeting is not normally an issue.
> >
This technique has already saved the industry, or at
least bought "this much" time.
Probable knee breaker is the proximity to the next like
device, cascading across a 12" board. Pray for peripheral
arrays and adequate device-to-device pitch? ("But the parts
fit!") Is there a guideline pins-per-square-inch-per-side-
times-board-area where this technique saturates?
When and where is the parasitics-based testing technology
going to come rescue this situation? Haven't heard a peep
on this for maybe a year, but I'll confess I haven't been
looking. Promised to work on a probe-once-per-net basis
rather than all endpoints. Or how about the "touchless"
radiation/excitation?
Regards to all,
--
Jeff Seeger Applied CAD Knowledge Inc
Chief Technical Officer Tyngsboro, MA 01879
jseeger "at" appliedcad "dot" com 978 649 9800
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