Craig:
Finer line widths and spaces require special consideration in all processes. As to the etching part, the
trick is to start with cupric chloride etchant and then eliminate the free acid from the etchant. As the
free acid normality increases, the etch factor goes down. While many boards are produced with an etch
factor of 2:1 or 2.5:1, by eliminating the free acid (0N) you can get etch factors of 6:1 or 7:1. Many
shops routinely produce 2 mil lines and spaces on 1/2 or 1 ounce copper and have even produced 0.5 mil
lines and spaces on 1/4 and 1/2 ounce copper at zero normal acid. On the other side of the spectrum, 8 mil
lines and spaces can be done on 5 ounce copper!
Best regards
Phil Culpovich
[log in to unmask]
>
>
> Date: Thu, 3 Sep 1998 09:11:25 +1200
> From: Craig McGlinchy <[log in to unmask]>
> Subject: Fine Line technology
>
> Hi there,
>
> I am a new PCB designer, and as part of my training I have been asked
> to investigate the limitations (and why these exist), and effects on
> cost/yield etc of using fine line technology.
>
> I would really appreciate it if you could pass on any information you may
> have regarding the above topic. I have listed a few questions below that
> I feel outline the scope of what I am expected to find out.
>
> 1) What are your minimum track width/spacing capabilities, and what is
> the limiting factor?
> ie. If you state your minimum is 5mil, why is it 5 rather than 4mil?
> Is this limit due to imaging process, or is it the etching process?
>
> 2) What about inner layers? Why are these different?
>
> 3) What about different types of boards, are these different? if so,
> why?
> eg, flexible, teflon etc
>
> 4) Why do you charge more, the finer the line width/spacing?
> ie. Why is 5/5 more expensive than 12/12?
>
> If you have any questions/comments, please don't hesitate to contact
> me.
>
> Best regards,
> Craig McGlinchy
> PCB Designer
> Tait Electronics Ltd
> Ph (64) 3 358-3399 extn 8509
> Fax (64) 3 358-0432
> email: [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
################################################################
|
