Mechanical bend and shock tests are routinely performed on SMT assemblies to ensure that they can sustain anticipated production, handling and end use conditions. The strains and strain rates applied to SMT assemblies during bend and shock testing can lead to a variety of failure modes in the vicinity of the solder joints. This document provides test methods to evaluate the susceptibility of printed board assembly (PBA) materials and designs to cohesive dielectric failure underneath surface mount technology (SMT) attach pads. The test methods, which include pin-pull, ball-pull, and ball shear, can be used to rank order and compare different printed board materials and design parameters.

TABLE OF CONTENTS

1 SCOPE                   
1.1 Performance Classification    
1.2 Definition of Terms  
1.2.1 BGA   
1.2.2 Component           
1.2.3 Solder Joint/Ball       
1.2.4 Pad Cratering               
1.3 Interpretation               
 

2 APPLICABLE DOCUMENTS          
2.1 IPC                    
2.2 Joint Electron Device Engineering Council    

3 TEST METHODS             
3.1 General               
3.2 Test Coupons               
3.3 Pad Cratering Test Method Comparison    
3.4 Pin-Pull Test Method             
3.4.1 Procedure Description            
3.4.2 Critical Test Variables             
3.4.3 Test Apparatus               
3.4.4 Solder Application Process           
3.4.5 Heater Calibration              
3.4.6 Test Board Fixturing             
3.4.7 Test Procedure               
3.5 Ball-Pull Test Method            
3.5.1 Test Prerequisites              
3.5.2 Critical Test Variables        
3.5.3 Sample Preparation           
3.5.4 Equipment Setup              
3.5.5 Testing Method               
3.6 Ball-Shear Test Method           
3.6.1 Procedure Test Method Details        
3.6.2 Critical Test Variables            
3.6.3 Test Apparatus              
3.6.4 Test Board Fixturing            
3.6.5 Test Setup and Testing Procedure      
3.7 Failure Inspection Procedure         
3.7.1 Failure Modes               
3.7.2 Test Sample Size and Results Reporting     
 

4 REFERENCES         

FIGURES
Figure 3-1 Example Failure Mode Categories Occurring
in a BGA PBA Assembly          
Figure 3-2 Example of a Pad Cratering Failure     
Figure 3-3 Definition of Pad Construction       
Figure 3-4 Test Setup Schematic           
Figure 3-5 Thermocouple Locations on Panel      
Figure 3-6 Thermocouple vs. Heater Temperature
Calibration               
Figure 3-7 Test Board Fixturing with Metal Plate    
Figure 3-8 Flowchart of Pin Pull Test Sequence     
Figure 3-9 Flux Application to Target Pad        
Figure 3-10 Test Pin Position             
Figure 3-11 Pull Test                 
Figure 3-12 Isolated Pad Array             
Figure 3-13 Paste or Ball Fixture           
Figure 3-14 Tool Alignment             
Figure 3-15 Jaw Alignment             
Figure 3-16 Ball-Shear Test Schematic         

TABLES
Table 3-1 Benefits and Challenges for Pin-Pull,
Ball-Pull, and Ball-Shear Tests        
Table 3-2 Summary of Key Variables for Pin-Pull Test  
Table 3-3 Summary of Key Variables for Ball-Pull Test  
Table 3-4 Ball-Pull Testing Parameters        
Table 3-5 Critical Variables for Ball-Shear Test    
Table 3-6 Ball-Shear Test Parameter Settings     
Table 3-7 Typical Failure Modes          
Table 3-8 Examples of Failure Modes        
Table 3-9 Example Results Reporting Template