Howard,

Paco says that the material is good up to 198C and 700 psi. However they
recommend 175-300 psi to prevent image transfer, and perhaps the dish down
you described. Try lowering the lamination pressure some. The pressure
should be applied immediately so the PacoVia's polyolefin core layer can
flow and conform to the board well before the resin flows.

The heating rate seems a little slow, but should not be aggravating your
problem.

Is the problem localized, or everywhere? Is it the same on various parts?
Are you using enough conformal material to get an even pressure distribution
in the PacoVia?

A cooling rate >11C/min can cause excessive shrinkage in the PacoVia that
leads to high shearing forces and may be why you see the PacoVia's release
layer as residue on the plates.

Andy Magee
Flex Guru
[log in to unmask]
(937) 435-3629

[log in to unmask] wrote:

> Andy,
>
> My lamination parameter as follows:
> Pressure 300 psi
> Temp. 185 C
> Heating rate 1.5 C/min.
> What's your opinion on the parameter for  PACO VIA application?
> I concern another issue for PACO VIA . It will cause the edge of opening
> a little down. It means the surface of blind via is not so plate. Do you
> have the same phenomenon?
> Best Regards,
>
> Howard Lin
> Maxedge RD Center
>

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