To my knowledge, there is no IPC standard requirement (or method) for during/post assembly; much to the package manufacturer's chagrin.

Chris


Chris Mahanna
Robisan Laboratory Inc.





-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Wednesday, May 16, 2018 11:04 AM
To: [log in to unmask]
Subject: Re: [TN] Bow and Twist measurements per IPC 650 TM 2.4.22, IPC 600-2.11 Flatness

Folks,

   Is there a consensus, especially from committee (7-11D) members, on the above inquiry regarding Bow & Twist for raw board and PCBAs (populated boards)?

Ref:     IPC-T-50M (May – 2015)  ( Victor’s comments )
            Bow -  (Fabric)   Filing yarn that lies in an arc across the width of a fabric.
            Twist -  The deformation of a rectangular sheet, panel, or printed board, that occur parallel to a diagonal across its surface, such that one of the corners of the sheet is not in the plane
                          that contains the other three corners.

Victor,

From: Jose A Rios [mailto:[log in to unmask]]
Sent: Wednesday, May 16, 2018 8:35 AM
To: TechNet E-Mail Forum; Hernandez, Victor G
Subject: Re: [TN] Bow and Twist measurements per IPC 650 TM 2.4.22, IPC 600-2.11 Flatness

2.4.22 is only for bare (unpopulated) PWB’s, and the rigid portion of rigid-flex PWB's. Section 1 (Scope) explicitly excludes PCBA’s from being evaluated using this method.


José (Joey) Ríos, Sr QA Engineer
Mission Assurance Manager
Kavli Institute for Astrophysics & Space Research Massachusetts Institute of Technology [log in to unmask]<mailto:[log in to unmask]>
(617)324-6272

On May 16, 2018, at 7:17 AM, [log in to unmask]<mailto:[log in to unmask]> wrote:

Fellow TechNetters:

  Is there a separate Bow & Twist Test/documentation for Printed Wire Boards, PWB, and Printed Wire Board Assemblies, PWBAs?   Are they interchangeable......

Victor,