In situ Decapsulation of Plastic Encapsulated Devices Mounted to a Printed Circuit Board

2002 ◽  
Author(s):  
Ronald R. Hylton
Keyword(s):  
Printed Circuit Board ◽  
Failure Mechanisms ◽  
Circuit Board ◽  
Printed Circuit ◽  
Board Material

Abstract In situ decapsulation of plastic devices can be used to avoid the removal or alteration of failure mechanisms caused by exposure to desoldering temperatures. This paper describes techniques to decapsulate devices mounted to a printed circuit board using materials that are readily available and easily customized to specific applications. The techniques are extended to the decapsulation of other packaging technologies, such as SBGA packages and chip-on-board assemblies. Finally, post decapsulation cleaning techniques that will not harm the printed circuit board material are presented.

Estimation Of Complex Permittivity Of Printed Circuit Board Material Using Waveguide Measurements

1996 ◽  
Vol 430 ◽  
Author(s):  
C. J. Reddy ◽  
M. D. Deshpande ◽  
G. A. Hanidu
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Complex Permittivity ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
The Finite Element Method ◽  
Printed Circuit ◽  
X Band ◽  
Board Material ◽  
Raphson Method

AbstractA simple waveguide measurement technique is presented to determine the complex permittivity of printed circuit board material. The printed circuit board with metal coating removed from both sides and cut into size which is the same as the cross section of the waveguide is loaded in a short X-band rectangular waveguide. Using a network analyzer, the reflection coefficient of the shorted waveguide(loaded with the sample) is measured. Using the Finite Element Method(FEM) the exact reflection coefficient of the shorted wavguide(loaded with the sample) is determined as a function of dielectric constant. Matching the measured value of the reflection coefficient with the reflection value calculated using FEM and utilizing Newton-Raphson Method, an estimate of the dielectric constant of a printed circuit board material is obtained. A comparison of estimated values of permittivity constant obtained using the present approach with the available data.

Failure analysis on cracking of blind and buried vias of printed circuit board for high-end mobile phones

2019 ◽  
Vol 31 (4) ◽  
pp. 203-210
Author(s):  
Jie Tang ◽  
Yi Gong ◽  
Zhen-Guo Yang
Keyword(s):  
Failure Analysis ◽  
Mobile Phones ◽  
Printed Circuit Board ◽  
Failure Mechanisms ◽  
Performance Testing ◽  
Circuit Board ◽  
Chemical Compositions ◽  
Content Type ◽  
Printed Circuit ◽  
Prevention Methods

Purpose The submitted paper is mainly concerned with the cracking of blind and buried vias of printed circuit board (PCB) for smartphones which were encountered with abnormal display problems like scramble display or no display during service and had to be recalled. Design/methodology/approach To found out the root causes of this failure and dissolve this commercial dispute, comprehensive failure analysis was performed on the printed circuit board assemblies (PCBAs) and PCBs of the failed smartphone, such as macrograph and micrograph observation, chemical compositions analysis, thermal performance testing and blind via pull-off experiment, which finally helped to determine the causes. Besides that, the failure mechanisms were discussed in detail, and pertinent countermeasures were proposed point by point. Findings It was found that the PCB blind vias cracking was the main reason for the scramble display or no display of the smartphone, and the incomplete cleaning process before copper plating was the root cause of the blind vias cracking. Practical implications Achievement of this paper would not only help to provide the solid evidence for determining the responsibility of this commercial dispute but also lead to a better understanding of the failure mechanisms and prevention methods for similar failure cases of other advanced mobile phones. Originality/value Most failure analysis researches of PCBAs only focused on the unqualified products from manufacturing, while this paper addressed a failure analysis case of PCBAs products for smartphones from actual services, which was relatively rarely reported in the past.

Strain-Based Flexure Assessment for the Printed Circuit Board Assembly Environment

2005 ◽  
Author(s):  
W. Carter Ralph ◽  
Frank W. Joyce
Keyword(s):  
Printed Circuit Board ◽  
Failure Mechanisms ◽  
Mechanical Damage ◽  
Circuit Board ◽  
Printed Circuit Board Assembly ◽  
Printed Circuit ◽  
Detailed Method ◽  
Increased Risk ◽  
Specific Strain ◽  
Circuit Board Assembly

Mechanical damage to due to over-flexure is an increasing concern in the printed circuit board assembly environment. This damage can result in part rejection during manufacturing, or may combine with other failure mechanisms to result in field returns. Therefore, flexure control during circuit board assembly is a vital part of overall product quality. A metric has been developed for component-specific strain-based flexure limits using a spherical bend mode and a novel strain metric, along with a detailed method for strain gage measurement in the assembly environment. This paper presents a review of the trends that have contributed to the increased risk of damage, as well as the development of the diagonal strain metric and the use of the spherical bend mode. These methods have been successfully employed to identify excessive flexure and reduce risks to function and reliability. Two case studies that demonstrate the application and effectiveness of the procedures are presented.

Filler effect of low loss dielectricity in printed circuit board material

2007 ◽  
Vol 23 (2-4) ◽  
pp. 141-145 ◽  
Author(s):  
Jiae Lee ◽  
Hyosoon Shin ◽  
Jonghee Kim ◽  
Hogyu Yoon
Keyword(s):  
Printed Circuit Board ◽  
Circuit Board ◽  
Low Loss ◽  
Printed Circuit ◽  
Board Material
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