TECHNET Archives

May 2005

TechNet@IPC.ORG

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 >>]

Print Reply
Subject:
From:
Jeffrey Bush <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jeffrey Bush <[log in to unmask]>
Date:
Thu, 5 May 2005 10:08:34 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (109 lines)
What about other factors in drilling beyond machine accuracy - pin
tolerance, pin to tooling tolerance, and pin to bed tolerance.  These
factors are also constituents in the overall drill accuracy beyond the
machine tolerances native to the process.

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive - POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com
 

-----Original Message-----
From: Roger Stoops [mailto:[log in to unmask]] 
Sent: Thursday, May 05, 2005 9:30 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole drill accuracy

If the alignment is off by 2mils or more, sounds like your fab house
needs to check their drilling machine, or else use a better, more
accurate one than typically used.  The issue is one of positional
accuracy plus repeatability.  If a machine has a drilling accuracy of
+/-.001, positional accuracy of +/-.0005, and repeatability of +/-.0005,
then the total accumulated tolerance can be as large as +/-.002.

Sound like you need to specify a location tolerance (true position) of
+/-.0015 (or better) for the holes in question.  The wider the tolerance
for hole diameter, the narrower the tolerance for location accuracy, and
vice versa, for press-fit connectors.  IPC-2221 9.2.2 says you can
expect +/-.002 for fabs built to level B. Asking for Level C would give
you +/-.0015 tolerance. (If I'm missing something, somebody *please* set
me on the straight and narrow...)

Use of GD&T (IPC-2615) would help in specifying what you really want,
because tolerance zones with GD&T are round, not square as in the
(unfortunately) typical drawing practice.

All said and done: it's up to you to specify hole size, tolerance, *and*
accuracy for your design.  If you don't specify accuracy, the board
vendor may provide you with what's easy for them to make, to the widest
tolerances possible.


Best Regards,
Roger

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Scott Lefebvre
Sent: Wednesday, May 04, 2005 6:10 PM
To: [log in to unmask]
Subject: [TN] Through hole drill accuracy

I have looked profusely at IPC-6012 for a specification I could not
find.  I need to know if there is a specification for PTH drill accuracy
and repeatability.  We have a press-fit connector we are having problems
with.  The component manufacturer tested one of our boards and said the
alignment is off 2 mils or more in some locations.  I could not find
what is the spec in IPC to reference to, could someone please point me
to the correct document I should look at.
 
Sincerely,
 
SCOTT L
 
 

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2