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warpage for 152mm length PCB

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#66989

warpage for 152mm length PCB | 9 August, 2012

I would like to understand What will be the allowable warpage for 152mm length PCB. We are observing about 1.5mm warpage. Is that acceptable? Could you please share method to calculate the warpage

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#66990

warpage for 152mm length PCB | 9 August, 2012

Allowable bow & twist: Together, both IPC-A-600G and IPC-6012B represent the core IPC documents for describing the acceptable and nonconforming conditions that are either externally or internally visible on finished printed boards. IPC-A-600G relies on IPC-6012 for the minimum acceptability requirements for PCBs and the acceptance testing frequencies required for PCB manufacture and procurement. IPC-6012 relies on IPC-A-600G for visual support and interpretation of those requirements.

IPC-6012B with Amendment 1, 3.4.3 Bow and Twist. Unless otherwise specied in the procurement documentation, when designed in accordance with 5.2.4 of IPC-2221, the printed board shall have a maximum bow and twist of 0.75% for boards that use surface mount components and 1.5% for all other boards. Panels which contain multiple printed boards which are assembled on the panel and later separated shall be assessed in panel form. Bow, twist, or any combination thereof, shall be deter-mined by physical measurement and percentage calculation in accordance with IPC-TM-650, Method 2.4.22.

IPC-2221, 5.2.4 Bow and Twist: Unless otherwise specified on the master drawing, the maximum bow and twist shall be 0.75% for boards that use surface mount components and 1.5% for all other board technologies. Panels that contain multiple printed boards to be assembled on the panel and later separated shall also meet these bow and twist requirements.

IPC-TM-650, 2.4.22c, Bow and Twist (Percentage): http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2.4.22c.pdf

Here's more: Implementing High Temperature Coplanarity Requirements for Components and PWBs http://thor.inemi.org/webdownload/projects/ba/Board_Coplanarity/Board_Coplanarity_Background.pdf

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