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November 1999

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Brian Ellis <[log in to unmask]>
Date:
Mon, 22 Nov 1999 12:33:54 +0800
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"TechNet E-Mail Forum." <[log in to unmask]>, Lum Wee Mei <[log in to unmask]>
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Lum Wee Mei <[log in to unmask]>
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Out of curosity, why is HAL not recommended for controlled Zo?

Thanks.

Brian Ellis wrote:

> Hi!
>
> I do not recommend HAL for UHF boards: the flux residues are damn hard
> to remove and the hygroscopicity of them may be limitative, especially
> if you do decide on an FR-4. You may also care to consider 35 µm copper
> (1 oz) on the inner layers for a better connection to through
> holes/vias. Does the fact that 2 x 1080 is specified suggest controlled
> impedance? If so, be prepared to find the high resin:glass ratio will
> give a slightly higher dielectric constant than a more usual build. Also
> HAL is definitely NOT recommended for controlled Zo.
>
> Brian
>
> Ko Adeline-FSGA2298 wrote:
> >
> > > Hi there,
> > >
> > > My engineer is asking me to design a 900Mhz 4-layer brd using the
> > > following information.
> > > As this is my first time doing such a high freq brd.
> > > I wish to know,  is this PCB material perform excellent in high freq.
> > >
> > > PCB Info
> > > Top layer     --> 1/2 oz copper
> > > Prepreg       --> 2 X 1080
> > > Layer 2               --> 1/2 oz copper
> > > Prepreg               --> 2 X 7118
> > > Layer 3               --> 1/2 oz copper
> > > Prepreg       --> 2 X 1080
> > > Bottom                --> 1/2 oz copper
> > >
> > > Brd finishing thickness : 0.031" +/- 0.005"
> > > Material : FR4.
> > > Plating : Tin / Lead  63/37 HAL
> > >
> > > Thanks & Best Rdgs
> > > Adeline Ko
> >
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