I don't know if this help's you much but our customers spec for your same situatiion is 20.0 in/lbs. This has not been a problem in the past. One note is that we calibrate our torque drivers once a month. Hope this helps ______________________________ Reply Separator _________________________________ Subject: Torque Author: [log in to unmask] at ~INTERNET Date: 10/13/95 9:05 AM Received: by ccmail Received: from netcomsv by pragma.com (UUPC/extended 1.11) with UUCP; Fri, 13 Oct 1995 09:04:48 PDT Received: from miso.wwa.com by netcomsv.netcom.com with SMTP (8.6.12/SMI-4.1) id IAA07489; Fri, 13 Oct 1995 08:46:16 -0700 Resent-Date: Fri, 13 Oct 1995 08:46:16 -0700 Received: from ipc by miso.wwa.com with uucp (Smail3.1.28.1 #8) id m0t3mJw-000iDZC; Fri, 13 Oct 95 10:46 CDT Received: by ipchq.com (Smail3.1.28.1 #2) id m0t3l5w-0000GpC; Fri, 13 Oct 95 09:28 CDT Old-Return-Path: <miso!uunet.uu.net!medar!medar.com!mcussen> Message-Id: <[log in to unmask]> Date: Fri, 13 Oct 95 07:36 EDT From: [log in to unmask] (Mike Cussen) X-ccAdmin: postmaster@netcomsv To: [log in to unmask] Subject: Torque Cc: [log in to unmask] X-Sun-Charset: US-ASCII Resent-Message-ID: <"9ZXCA1.0.NsA.2UdVm"@ipc> Resent-From: [log in to unmask] X-ccAdmin: postmaster@netcomsv X-Mailing-List: <[log in to unmask]> archive/latest/1359 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] Dear Scholars, I would like to know if there is information available, or opinions that address this subject of torque. September 20, 1995 Our design engineers have requested a torque specification for a circuit board. This is a two layers board, FR-4 material, thickness 0.062", and copper is 2oz. This torque requirement is due to a mechanical assembly operation. We are inserting a threaded SCR through the circuit board, where we will secure this device with a lock washer and nut. This assembly operation is very similar to your (IPC'S) description on page 10, fig. 2-10 of the "Acceptability of Electronic Assemblies," the only difference is there is no insulating washer. I do have the torque specification for the part being assembled which is 22 Lb.in (US-units), and I found no problems with this pressure. Still the design engineer is requiring the torque specification for the FR-4 product. Can you please assist me in qualifing this torque requirement. My first concers are, could an assembler tighten this part tight enough to crush the barrels or feed-throughs. "I will answer that myself," if no constraints are given, sure with a big enough vise or lever damage would occur. Sincerely your, Medar Inc, Michael Cussen