We have recently been experiencing some issues Drilling the above material.
We currently run chiploads in the 1.0 to 1.7 range drilling 1-2 high on
Excellon Mark 6 ( air bearing) equipment. Retract Rate is between 500-800.
Drill/Spindle/Collet maintenance is current and run-out well within limits.
Drill bits are all new and supplied by HAM. We have experience with Kemmer,
International Carbide and a few others without seeing significant
differences. We have performed numerous feed and speed studies ( including
every conceivable combination of back-up and entry from various
manufacturers) which have led to the above chiploads and retract rate. What
we are seeing in our Cross-section Analysis are Glass Bundles and apart and
separate from these Teflon fibers extending 2+ Mils into the hole. With
subsequent Plating we experience nodule formation and reduction in hole
size leading to Non-conformance to the Customers requirements. The  typical
hole size range and tolerance were dealing with is 0.043-0.055 inches
plus .003/ minus.001 inches. We are using an Advanced Plasma unit for Hole
conditioning and have even gone to an Ammonium Bifluoride Glass Etch
process to at least try to remove the Glass. We use Direct Metallization
instead of Electroless.

Has anyone else being seeing these issues? And/Or do you have any
recommendations?
We also believe that there may be Lot to Lot or within lot variation. Our
feedback from the Supplier was recommendations for Chiploads in the
neighborhood of 5.0. This yielded raised burrs on the entry side of the
material at all retract rates.
Any feedback would be appreciated!
By the way we drill many other forms of Teflon here and have seen excellent
results with the above Drilling Parameters and other mentioned processes.
Thanks,
Craig Ropp
[log in to unmask]

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------