Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Thursday, July 17, 2003 4:33 AM
Subject: Re: [Homebrew_PCBs] flex circuits by hand?


> thanks for that info about the purposes.
> i still do not like this flexible stuff.
> not for soldering components on it. as cable it is ok.
> but thats only my opinion.
>
> i guess you already read this:
>
> http://www.pcbspecialist.com/EBasematerial.htm
>
> search for flexible.
>
> may need writing some mails but may result in some samples?
>
>
> especially this note may be interesting: (Rolled ultra thin FR4 for
> flexible applications).
> it at matsushita...
>
> i would try this if it is flexible enough/can be used as cable/connector.
> because it should be the same to use as thick fr4, i do not trust this
> plastic foil things very much ;-).
>
> keep us informed please if you get something.
>
>
> there are loads of "flexible material" providers in the above list url.
> if you check all homepages and write a mail to every interesting one you
> get some samples for sure.
>
> check all and choose the best. i think the materials may need photoresist
> coating done by you.
> this is no problem i think. but putting the copper on i would not think to
> be possible so easy.
>
>
> hope you find some material...
>
> regards
> stefan
Stefan, thanks for the URL, (I had missed it) it is very informative. The
best part is that a number of the companies are local, and I guess i never
even thought that they made flex materials. I toured Isola during one of our
IEEE meetings a couple years ago, looks like I will need to talk with them
again.

You might be onto something with the soldering. In reflow, the temps are
failry well controlled, but during hand operations, it would seem pretty
easy to over temp the laminate and cause all sorts of failure modes.

You also asked about my applications. The first one is a dual planar
antenna. I'd rather use a flex circuit in that the mechanical geometries are
easier to deal with, and I want to find out the effective impedance as a
function of physical distortion. It doesn't lend itself to modeling at least
not with my old version of NEC, and hopefully I can play with the geometry
such that when I switch to FR4 and recalculate the basic geometry, I will
find critical areas where tolerance must be held. Otherwise, I would
probably go through a whole panel of FR4 planar antennas trying to determine
the critical geometry, as the antenna will be a 3D structure.

The 2nd application is a flexible light bar, sort of along the line of a
roll up keyboard, but that can be bent to fit into small recesses on my car
when doing repair work. I played with a fleixble exit sign light that uses
incandescents in a fleixible plastic tube, but the illumination is not very
uniform.

Thanks
Ron