LISTSERV - TECHNET Archives - LISTSERV.IPC.ORG

TECHNET Archives

February 1999

TechNet@IPC.ORG

	LISTSERV Archives
	TECHNET Home
	TECHNET February 1999

	Log In
	Register

	Subscribe or Unsubscribe

	Search Archives

Options:	Use Monospaced Font Show Text Part by Default Show All Mail Headers
Message:	[<< First] [< Prev] [Next >] [Last >>]
Topic:	[<< First] [< Prev] [Next >] [Last >>]
Author:	[<< First] [< Prev] [Next >] [Last >>]

Subject:	Solder Mask Clearances on dogbone vias
From:	"Alderete, Michael" <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Thu, 18 Feb 1999 10:45:18 -0800
Content-Type:	text/plain
Parts/Attachments:	text/plain (59 lines)

Steve-

At previous employer, we specified, for example:

.025" dia. nominal pad
.031" dia. nominal clearance hole on soldermask
& soldermask registration of .003" dia. TP (true position)

such that at maximum allowable SM misregistration (.003" in any direction),
solder mask opening would at worst case be tangential to pad, and thus not
overlap the pad at all.

Board houses had no problem with this SM positional tolerance callout (10
layer glass-PI all SMT PWBs).

Michael Alderete



You wrote...
------------------------------

Date:    Wed, 17 Feb 1999 16:51:36 -0800
From:    "Joy, Stephen C" <[log in to unmask]>
Subject: Solder Mask Clearances on dogbone vias

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

------_=_NextPart_000_01BE5AD8.D67B4FFE
Content-Type: text/plain;
        charset="iso-8859-1"

We are looking at the design rules for soldermask clearances on mini BGAs.
The current rules say the solder mask will be .006" greater than the nominal
hole size.
I have 2 questions.
What is the resolution capability of solder masks? Can solder masks reliably
resolve a .006" line?
What is the current capability for solder mask registration? I would like to
spec nominal FHS+.002"/side as the solder mask opening with no s/m in the
hole.
Thanks,
Steve

------_=

################################################################
TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################

ATOM RSS1 RSS2

LISTSERV.IPC.ORG