V5.0 - 00137 Non-Delivered July 2 , 2004

Source:

Naprotek, June 23, 2004

Symptoms:

Probing after reflow identified open between JP9-18 and R95-6.
Naprotek technician confirmed open circuit.

Analyst(s):

Przybylski

Analysis Procedure(s), Findings:

With an ohm meter, confirmed open ckt between U50.Y20 and R441.3. No other vias on the way.
This is a non critical function, an R-2R ladder input for a pulser we don't generally use.
With ohm-meter, confirmed open U35-45 to U50.H14. There is a via in between, with continuity to U35.
The open circuit is at the U54 side. When running a flash download, no activity can be seen at the via under U50.

Root cause:

Possibly faulty drilling or PTH plating plating under EPXA4.

Mitigation:

TBD
If the BGA is removed, the via under it can be tested from both sides. If the via is OK, the board is recoverable by replacing the EPXA4 with a new one. Otherwise, the board may be unrecoverable without resorting to extraordinary measures, like routing a green wire out under the BGA before remounting it.

Disposition:

Awaiting further review by vendor.

Any Other Information:

none