TECHNET Archives

April 2004

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:
Dave Chapman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 21 Apr 2004 05:25:14 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (140 lines)
When we receive warped boards and there isn't time to return to vendor we
can put the boards on the mesh chain and run them through the oven, this
help flatten them out for assembly. A careful review of available copper
throughout the PWB is in order as even cooling is critical to PWB flatness
even in small boards.
Dave C.

-----Original Message-----
From: Dale Ritzen [mailto:[log in to unmask]]
Sent: Tuesday, April 20, 2004 4:14 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance


Victor,
This is derived from a measurement of the diameter D, length L and width W
of the board (or palletized board) in question, using a calibrated roll pin
of known value. Page to the back of your IPC-A-600 book. The TM-650 section
shows how to make this measurement and what the measurements are based on.
Just be sure you use a calibrated flat granite stone when you do the roll
pin measurements for the calculations. The flatness of the measuring device
can make a difference.

We do this all the time in our incoming inspection area and have caught
quite a few badly bowed boards recently. Just remember, they can sometimes
be annealed back to correct flatness by the supplier.

Dale Ritzen, CQA
Quality Manager
Austin Manufacturing Services

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Victor G. Hernandez
Sent: Tuesday, April 20, 2004 4:00 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance


Ramon,

   I have seen the 1.5% and 0.75% criteria before.   What I am not sure
is % of what base number.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Tuesday, April 20, 2004 1:07 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Raw card Boe & Twist Tolerance


        Hi Victor:
                 It should definitely be less than 1.5% for THT and less
than 0.75% for SMT, which that is what it is for a board after it has
been soldered.
        JStd.001B 9.2.3
        Regards,
        Ramon

> -----Original Message-----
> From: Victor G. Hernandez [SMTP:[log in to unmask]]
> Sent: Tuesday, April 20, 2004 1:02 PM
> To:   [log in to unmask]
> Subject:      [TN] PCB Raw card Boe & Twist Tolerance
>
> Steve,
>
>     What has been your experience with measuring Bow & Twist on a raw
> card.   Is there a RULE Of Thumb that can apply generically.
>
> Victor,
>
> ---------------------------------------------------
> 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 847-509-9700 ext.5315
> -----------------------------------------------------

---------------------------------------------------
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
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
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
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
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
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
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 847-509-9700 ext.5315
-----------------------------------------------------

ATOM RSS1 RSS2