Transcription of IPC-TM-650 TEST METHODS MANUAL
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IPC-TM-650 TEST METHODS MANUAL
1 ScopeThis test method covers three procedures used todetermine the bow and twist percentage of individual rigidprinted boards, rigid portions of rigid-flex printed boards,and/or multiple printed panels. Measurements on non-rectangular samples pose a unique testing problem and maynecessitate careful evaluation of the requirements imposed bythe users of this test method. This test method does notdescribe the special considerations necessary when testingthe bow and twist of printed board assemblies ( , compo-nent placement & weight, edge supports & connectors, etc.).The first two procedures describe production (Go/No-Go) METHODS that generally characterize the bow and twist asbeing no more than a specific value. The other procedure is areferee method used to precisely determine the DefinitionsBow and twist are defined in definitions are repeated in this test method for Bow (Sheet, Panel, or Printed Board)The devia-tion from flatness of a board characterized by a roughly cylin-drical or spherical curvature such that, if the product is rect-angular, its four corners are in the same plane (see Figu)
5.3.2 Support the other two corners with leveling jacks or some other appropriate devices, ensuring the two raised cor-ners are of equal height from the datum surface. This may be checked by using the dial indicator (see Figure 7).
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