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Crack Test Method for Chip Ceramic Capacitors on Printing Circuit Board

IP.com Disclosure Number: IPCOM000117162D
Original Publication Date: 1996-Jan-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Murata, K: AUTHOR

Abstract

Disclosed is a crack simulation testing method and a crack finding method for chip ceramic capacitors to achieve the crack-free in chip ceramic capacitors on Printing Circuit Board (PCB) and to prevent a smoking incident in the field (*). When PCB is divided into several parts, the mechanical stress causes the crack which is very difficult to find by current visual inspection or electrical test. This type of crack could be a cause of a smoking incident in the field 1. 1. Crack simulation testing method The ceramic capacitors have a weak point of poor mechanical strength, and one of the typical mechanical crack is caused by a dynamic stress such as PCB breaking. The crack simulation test is very important at the evaluation of chip ceramic capacitors to know its anti-crack characteristics.

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Crack Test Method for Chip Ceramic Capacitors on Printing Circuit
Board

      Disclosed is a crack simulation testing method and a crack
finding method for chip ceramic capacitors to achieve the crack-free
in chip ceramic capacitors on Printing Circuit Board (PCB) and to
prevent a smoking incident in the field (*).  When PCB is divided
into several parts, the mechanical stress causes the crack which is
very difficult to find by current visual inspection or electrical
test.  This type of crack could be a cause of a smoking incident in
the field 1.
  1.  Crack simulation testing method
        The ceramic capacitors have a weak point of poor mechanical
       strength, and one of the typical mechanical crack is caused by
a
       dynamic stress such as PCB breaking.  The crack simulation
test
       is very important at the evaluation of chip ceramic capacitors
to
       know its anti-crack characteristics.  This kind of mechanical
       test has not been done by capacitor makers or users.
        At first, the test samples are soldered by infrared reflow
       or fountain flow on PCB test pattern in parallel or in
       perpendicular as shown in Fig. 1.  PCB breaking line is
measured
       and marked up.  The test specimen is put upside down to avoid
       other mechanical stress and cut down along PCB breaking line
by
       the shearing machine as shown in Fig. 2.
  2.  Crack findi...