Li,



On our designs we typically use a non-plated through hole with an unsupported pad for mounting holes regardless of what the mating material might be.  The unsupported pad acts like a flat washer under the screw head.  For a hole that might be part of the grounding scheme we would use a plated through hole in that specific location.



I hope this helps.



Best regards,



Phil Nutting

Design for Manufacturing Engineer

Kaiser Systems, Inc.

126 Sohier Road

Beverly, MA 01915

voice: 978-922-9300 x1310

fax: 978-922-8374

e-mail: [log in to unmask]

www.kaisersystems.com





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of ??

Sent: Thursday, April 16, 2009 5:08 AM

To: [log in to unmask]

Subject: [TN] NPTH or PTH?



Dear all,



For the PCB assemble requirement, we always need NPTH or PHT holes to have screws fasten it on the related structure. Here is the quetion, when should we select NPTH holes or PHT holes?



For a meatal structure, a PHT hole maybe the best choice. For a plastic structure, a NPTH hole may be used, why?



B.R.

Li Yi



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