Steve,

You know I love you but, how did you get into this in the first place?

Surface copper gets plated "up" to a specified thickness based on hole
plating thickness requirements. If the hole is specified at 1 mil minimum,
usually the surface thickness plating is about 1.2 mils or so thick. The
inners are as specified except for thickness degradation from
cleaning/etching, etc.

Earl
----- Original Message -----
From: Stephen R. Gregory <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 06, 1999 2:57 PM
Subject: [TN] Two distinct layers of copper...


> Hi ya'll!
>
> Here's something weird I've never come across, but maybe some of you have.
We
> built this Hi-Rel board here that the PCB drawing calls out for 2-ounce
> copper.
>
> The board has this leaded SMT multi-capacitor part (it's like 3 huge
ceramic
> capacitors stacked on top of each other) and has 8-leads. After assembly,
and
> before we test then conformal coat it, we put the assembly on this
vibration
> table to go through some ESS.
>
> There's been a few of these capacitor deals come loose because they're so
top
> heavy, but that's a whole 'nuther issue...
>
> What we've been seeing on some of these boards, is that either the pad
> completely lets go from the laminate (it's a polyimide), or sometimes
we'll
> see the pad come up in what looks like a layer of copper, yet there's
still
> copper down on the PCB...as if the copper has split horizontally in two
> distinct layers? Is this possible? Does 2-ounce copper clad laminate get
the
> copper plated an ounce at a time? Is this a defect? I've never seen
something
> like this before, and I can take a picture and send it to ya' if you want
me
> to....
>
> Thanks!
>
> -Steve Gregory-
>
> ##############################################################
> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
> ##############################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
following text in
> the body:
> To subscribe:   SUBSCRIBE TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information.
> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
> 847-509-9700 ext.5365
> ##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################