In a message dated 98-12-16 22:20:04 EST, you write:

<< Wondering if someone can tell me the industries stand on reworking inner
 layers at black oxide. Would like to get the point of view from both the
 PCB manufacturer and end user. I realize that controls need to be in
 place so that the layers are not over etched and signal lines are not
 reduced, especially for controlled impedance layers. The first time the
 boards were oxided they had 40u' of copper etched away and I believe
 that by reworking and removing 20-30u' this should not effect the
 functionality of the boards. >>

Scott:

Everytime you run a panel down  a conventional chemistry oxide line, you
actually remove about 60 microinches, or 1.5 microns of Copper.

Assuming that the microetch removes about 40 microinches, the oxide itself,
assuming a standard black oxide, of 0.5mg/cm2, removes about 20 more
microinches of Copper metal to form the oxide.

We assume here that you are not stripping the oxide with a microetch, which
will remove even more Copper.

All of this assumes that you are using a microetch to prepare the panels for
oxide, and if you are, this maybe partly why you must rerun some panels.

We have shown superior oxide, and superior uniformity, and lower cost, using
an acid cleaner, rather than a microetch.

If you want more information, contact me directly off Technet, please.

Rudy Sedlak
RD Chemical Company
[log in to unmask]

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################