Bill,
As a test lab, I will tell that it can be done by a select few fabricators. There appears to be an art form to some of the items you mention.
One thing that you didn't mention, that IMO is probably the single biggest risk is desmear/etchback.
Many of the drawings/contracts out there require effective positive etchback on these parts. Sometimes limited to 1.5 or 2 mils.
Although I am a proponent of doing away with positive etchback, the reasoning may be logically sound for these parts, and it makes them almost impossible to build.
Chris
Chris Mahanna
Robisan Lab
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Simon Huetter
Sent: Wednesday, November 24, 2010 3:45 AM
To: [log in to unmask]
Subject: Re: [TN] Lamination of PTFE based materials for multilayer applications...
Brooks, Bill wrote:
> I was reading an article by Rich Trine from 2005 in Circuitree
> Magazine about the subject of Lamination of PTFE based materials for
> multilayer PCB applications...
>
>
<http://www.circuitree.com/Articles/Feature_Article/8a007da6a80f7010VgnVCM10
0000f932a8c0____>
>
> I'm curious if anyone has any experience with this subject and could
> explain the ins and outs of choosing to make a sequential laminated
> multilayer construction with PTFE and polyimide materials combined.
>
> Have things become any easier than the article seems to suggest?
> What would be the limit of sequential laminations you would do? How
> would you deal with the different CTE properties? Also, how would you
> deal with the differences in the temperature requirements for bonding
> of the thermosetting prepregs??
>
> Anyone done anything like this before? How did it turn out?
> Where can I find more research on the subject?
>
Hello Bill,
the pros and cons are very well described in the article and they are still valid. I'm not aware of any research on this subject but you can find technical articels from base material suppliers (e.g.
<http://www.rogerscorp.com/acm/literature.aspx>).
We produce PCB with the described techniques, fusion bonding, thermoplastic and thermoset materials with different bonding temperature, mixed material multilayer, sequential build ups, etc.
It's very important to use the right material for mixed material multilayer to avoid warp and twist, barrel cracks etc. I would say that there is no technical limit for sequential laminations but it's limited by costs.
I recommend that you contact an experienced PCB manufacturer if you have special requirements.
Best regards
Simon
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