If the plating is on a flat surface, measurements can be done in Angstroms which are 1\10,000 of a micron with great accuracy. It is done all the time in Semiconductor Fabs.
Ramon
A little history of Angstroms:
An ångström or aangstroem (the official transliteration), or angstrom (symbol Å) is a non-SI unit of length that is internationally recognized, equal to 0.1 nm. It is sometimes used in expressing the sizes of atoms, lengths of chemical bonds and visible-light spectra. It is named after Anders Jonas Ångström.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric CHRISTISON
Sent: Tuesday, March 13, 2007 12:27 PM
To: [log in to unmask]
Subject: Re: [TN] PCB plating Qualification
I apologise in advance for taking this thread off on a slight tangent but how do you check sub micron plating thickness to any degree of accuracy? I have often been told that it is very difficult to do.
Kane, Amol (349) wrote:
> In case of ENIG, the Ni and the Au thickness would be important too wont it?.....the idea here is (or what I thought would be) is to monitor the plating process of the supplier and compare it to the max and min specs of Ni and Au given in 4552 to ensure that you consistently get boards that will not be susceptible to Au embrittlement on one end to black pad on the other........seemed logical to me, and therefore wanted to know if this was a practice in the industry........
>
> Amol
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
> Sent: Tuesday, March 13, 2007 10:27 AM
> To: [log in to unmask]
> Subject: Re: [TN] PCB plating Qualification
>
> Hi Amol,
> I would be very much surprised if there were such efforts. Why
> undertake such an effort?
> The only plating thickness that is really critical is the copper
> plating thickness in the vias-and it will vary according to all kinds of variables.
>
> Werner
>
>
>
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