I just looked at steve's pictures and that is pretty much what every board
we build looks like. We build RF/Microwave assemblies and like steve says
ground is like God. We too put our boards in housings and no one ever sees
them after that. Unless you have a customer that is very cranky about this
kind of looking issue my two cents is to just say hey that is what happens
and that is how it is going to look.
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Thursday, May 03, 2001 4:43 PM
To: [log in to unmask]
Subject: Re: [TN] IPC standard for solder content on the back of PCBs?
Hi Matt,
We build a number of RF/Microwave assemblies here, and actually, we like to
see solder coming out the vias (so does our customer), because that's an
indication that the body of the part has a very good ground connection. I'm
no RF engineer, but I've
been told that is a pretty important aspect for things to function
correctly.
I've got a picture up of the bottomside of the board beneath a directional
coupler from Anaren, they call them "Xingers". Go to:
http://stevezeva.homestead.com/index.html
and click on Xingervias.jpg. Yeah, it don't look pretty, but this board goes
in a metal housing and nobody sees the bottom of it anyway...actually nobody
ever sees the board either when the whole deal is fully assembled. But the
solder coming out the vias is a good indication that you have a very good
connection to ground with the body of the device. These boards are similar
to
yours too...all gold plated.
-Steve Gregory-
> Hello..
> Does anyone know if there is an IPC standard for solder content on the
back
> of PCBs? My application is RF/Microwave filters mounted on PCBs. There
are
> components only on the top side and plated thru vias in various places on
> the PCB (for grounding, etc.). The bottom of the PCB has no soldered
> components and the PCB is FR-4 with 1oz Copper, Nickle barrier and Gold
> plating on both sides. Solder mask is on certain PCBs, and can be used
to
> help prevent solder from penetrating to the bottom of the PCB.
>
> The problem is for solder (during reflow) finding it's way from the top
of
> the PCB (where the solder paste is applied) down through the plated thru
> vias to the underside of the PCB. This solder is not enough to cause a
> solder ball or make the part fail for mechanical height specs, yet it is
> more of an aesthetic issue. Even if the solder is thick enough to be
wicked
> off, there is still a solder splash or stain on the plating. Is there an
> IPC (or other) spec for solder aesthetics?? If so, what number is it and
> what is the price for the document?
>
> The only solder IPC specs I can find seem to deal with solder fillets,
etc.
> for through hole mounted parts that have a component or components
mounted
> thru the PCB and soldered on 1 or both sides.
>
> Tnx
>
> Matthew Steger
> Product Design Engineer
> RF/Microwave Products
> Spectrum Control, Inc.
> * Phone: 717-361-4842
> * Fax: 717-361-4756
> * Email: [log in to unmask]
> * Mailing Address: 1595 S. Mt Joy St., Elizabethtown, PA 17022
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