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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