Mike,
        To achieve this size dam, how much tolerance do you need from the
edge of the pad for misregistration? I've got a vendor that says they can do
.003 dams, but they need another .0025 minimum on each side to prevent mask
on pad due to misregistration. Is this to be expected, needing a total pad
edge-to-edge spacing of .008 minimum?

Mike McMonagle
PCA Process Engineering Supervisor
K*Tec Electronics
1111 Gillingham Lane
Sugar Land, TX  77478
(281) 243-5639 Phone
(281) 243-5539 Fax
[log in to unmask]

> -----Original Message-----
> From: Mike Bailey [SMTP:[log in to unmask]]
> Sent: Wednesday, October 13, 1999 8:42 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Fab: Mask dams between fine pitch smt pads
>
> .0035 - .004 is within the capabilities of most shops, even on .5mm pitch
> devices.  Occasionally, this is an issue when small via holes in high
> aspect
> ratio boards must remain open after developing. It requires a slightly
> overdeveloped condition to clear all mask residue from the holes.
> Otherwise
> it is consistently achievable.
>
> -----Original Message-----
> From: Ed Cosper [mailto:[log in to unmask]]
> Sent: Wednesday, October 13, 1999 5:16 AM
> To: [log in to unmask]
> Subject: [TN] Fab: Mask dams between fine pitch smt pads
>
>
> Hi all,
>
> Just a quick industry capability questions. Are board manufactures still
> having trouble holding mask dams between fine pitch (19mil) SMT pads. As
> recent as a year or so ago I was under the impression that board shops
> would
> ask the remove these small dams when they got them on the Gerber data. Is
> this still common. I am interested in what most people think is feasible
> regarding mask dams that are 4 mils wide and smaller. All responses are
> appreciated.
>
> Ed Cosper
> ABC
>
> ##############################################################
> 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
##############################################################