On 6/12/06, Rich Graziano <rgrazia1@rochester.rr.com> wrote:
> Vasile:  You are a good guy to have on this list.

No. I'm just old and grumpy. Unfortunately "old" means a little experience
and nothing more. There is a true word here, with an approximate
translation: "Experience is what is making life with man and not what
is doing man with his life"
However, thank you for your too kind remark.

greetings,
Vasile

> Regards
> Rich
> ----- Original Message -----
> From: "Vasile Surducan" <piclist9@gmail.com>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Sunday, June 11, 2006 4:31 PM
> Subject: Re: [EE:] Visually determining PCB layer count
>
>
> > On 6/12/06, Florian Voelzke <FVoelzke@gmx.de> wrote:
> >> Vasile Surducan wrote:
> >> > On 6/10/06, Rich Graziano <rgrazia1@rochester.rr.com> wrote:
> >> >
> >> >>In my dumb way, I thought they were all compressed to the same
> >> >>thickness;
> >> >
> >> >
> >> > No way. The thickness is a matter of layer numbers and technology (ie
> >> > a RF board may be totally different because the epsilon of the
> >> > material determine the route impedance for the same substrate
> >> > material, industrial standard FR4). With a magnifier you can easily
> >> > make difference between 6 or 10 layers standard board. 10 layers have
> >> > bigger thickness than 6 layers. Between 2 and 4 layers could be no
> >> > difference in thikness but is viewable on cross section even without
> >> > magnifier.
> >>
> >> Yes and No...
> >>
> >> You can order PCBs in a big range of thickness - if you really want.
> >>  From very thin (below 0.5mm, 20mil) to very thick (beyond 3.2mm,
> >> 125mil). The normally seen 1.6mm is just a standard thickness (at least
> >> in europe). The thickness is usually not a direct result of the layer
> >> number.
> >>
> >> A multilayer PCB consists of several base material sheets and prepregs.
> >> By varying the number and thickness of these a large range of layers is
> >> possible in a large range of PCB thickness. AFAIK a 10 layer board in
> >> standard thickness should no problem at all.
> >
> >   Let's count 6mil between two layers, 10 layer = 9x6mil = 55 mil (1.4mm)
> >   1 oz per layer = 10 oz = 0.35mm total 0.9+0.35=1.75mm
> >
> >  So you may do it at limit with only 0.5oz or with a perfect prepreg
> > arrangement.
> >  Now, how easy you found 6mil prepreg, or when 0.5 oz is a good choice ?
> >
> >  I think you was to generous with "no problem at all".
> >
> > greetings,
> > Vasile
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