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October 2004

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Subject:
From:
Jeffrey Bush <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jeffrey Bush <[log in to unmask]>
Date:
Fri, 1 Oct 2004 09:33:37 -0400
Content-Type:
text/plain
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text/plain (120 lines)
What is the purpose of the via filling - via in pad or just to close the
via?



Jeffrey Bush
Director, Quality Assurance and Technical Support

                          76 Technology Drive - POB 1890
                             Brattleboro, Vermont 05302-1890
                                Tel. 802.257.4571.21 Fax. 802.257.0011
                                    [log in to unmask]
                              http://www.vtcircuits.com	



-----Original Message-----
From: Tempea, Ioan [mailto:[log in to unmask]] 
Sent: Friday, October 01, 2004 9:22 AM
To: [log in to unmask]
Subject: Re: [TN] Via filling


Thank you Werner,

I'm saving it in the right place now.

But does the filling percentage play a role? Should I push my PCB
suppliers to measure and guarantee something close to 100% filling?

One supplier told me they are printing the solder mask in the vias and
check with blotting paper if the stuff gets through. And if not, they
make a second pass. For me this is an overkill and we must be paying
something extra for it.

By the way, our products are telecom, some for outdoors and high-rel,
like 911 systems and power line protection.

Best regards,
Ioan

> -----Original Message-----
> From: Werner Engelmaier [SMTP:[log in to unmask]]
> Sent: Friday, October 01, 2004 9:02 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Via filling
>
> Hi Ioan,
> PTVs filled with solder mask/epoxy during the soldering processes will

> experience less compressive loads on the copper barrel, and thus less 
> tensile stresses which are part of the loading leading to innerlayer 
> separation. During
> operationall use, this fill plys no significant reliability role.
> PTVs filled with solder of course offer no advantage during the
soldering
> processes--they are filled during them. In operational use, fully
filled
> PTVs are
> subjected to reduced loads on the copper barrel than empty ones, and
PTVs
> with voids in the solder fill will experience localized higher loads
due
> to the
> stress concentrations---having said this, it needs to be emphasized
that
> this
> is only significant if the operational conditions are severe, such
> military and
> automotive.
>
> Regards,
> Werner Engelmaier
> Engelmaier Associates, L.C.
> Electronic Packaging, Interconnection and Reliability Consulting 7 
> Jasmine Run Ormond Beach, FL 32174 USA
> Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
> E-mail: [log in to unmask], Website: www.engelmaier.com
>
>
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