Daan,
        We normally specify +/- .007" (+/- .18 mm) for boards up to 12
layers. Above that, we specify +/- .010" (+/- .25 mm). Of course, we're
manufacturing these in the States. European manufacturers may have different
requirements. I suggest you do an informal poll of your vendors for
recommendations.

Michael Hiteshew
Lockheed Martin NE&SS-Baltimore
[log in to unmask]
(410) 682-1259

> ----------
> From:         d. terstegge[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;d. terstegge
> Sent:         Wednesday, July 05, 2000 11:55 AM
> To:   [log in to unmask]
> Subject:      [TN] Tolerance on board thickness
>
> Hi Technet,
>
> It's quiet on Technet. Or is it just me ? Problems with the server again ?
> Compensation for all the double messages from a few weeks ago ?
> Anyway, I've got a small question :
> We've ordered a 4 layer FR4 board with a thickness specification of 1.6
> +/- 0.05 mm. The supplier says he can't build it with such narrow
> tolarances. The customer won't accept anything worse than this.
> What do you think, should the average fabhouse be able to build a board
> like this or is it completely unrealistic ?
> Hope to hear from you.
>
> Kind Regards,
>
> Daan Terstegge
> SMT Centre
> Signaal Communications
> Unclassified mail
> Personal Website: http://surf.to/smtinfo
>
>

##############################################################
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 Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################