In today's era of aggressive pricing there is a need to give a relook to
certain discarded processes which were quite cost effective compared to
their successors. Reverting to Screen Printing for Double Sided PTH
Boards having 0.2mm traces and 0.2mm( 8 mil) spacing appears feasible.
Would someone with experience in this field address the following
queries:

1. Choice of Screen Mesh & Grade ? SS or monofilament? HD or T ?

2. Type of Screen Frame- construction? Optimum screen tension?

3. Hardness of squeegee rubber & squeegee angle for printing?

4. Screen height (gap) from the plane of the panel while printing?

5. Type of Stencil Film and proper procedure for adhering it to the
screen mesh?
   Direct or Indirect?

6. Ink rheology- viscosity? Thinner proportion? Any Brand preference?

7. Any 'pre-baking' or 'air drying' required before pattern plating?

8. Stripping medium ? Concentration and Temperature of the solution
before    etching?

9. Rework process? What if the boards require strip[ping and reprinting?

10 Any adverse effect in Copper Plating or Tin Lead Plating ?

Many thanks in anticipation.

P.V. Khan
Chief Quality Manager
Linaks Microelectronics Limited 
Fax:+91-522-222061, 315978  E-Mail: [log in to unmask]

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************