Patent ID: 11953538
Assignee: WUHAN UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 3:
4. The method according to claim 3, wherein step S3 further comprises:
S3.1: changing the shape parameter and the size parameter of the failure probability distribution of the solder layer to obtain the lifetime of the solder layer, changing the shape parameter and the size parameter of the failure probability distribution of the bonding wire to obtain the lifetime of the bonding wire, calculating the difference percentage between the lifetime of the solder layer and the lifetime of the bonding wire through, Δ
    ⁢
    N
   
   =
   
    
     
      ❘
      "\[LeftBracketingBar]"
     
     
      
       N
       2
       ′
      
      -
      
       N
       1
       ′
      
     
     
      ❘
      "\[RightBracketingBar]"
     
    
    
     min
     ⁢
     
      {
      
       
        N
        1
        ′
       
       ,
       
        N
        2
        ′
       
      
      }
     
    
   
  
  ,, wherein N1′ is the lifetime of the solder layer, and N2′ is the lifetime of the bonding wire;
S3.2: calculating the lifetime change rate ΔNf-IGBT before coupling and after coupling through, Δ
    ⁢
    
     N
     
      f
      -
      IGBT
     
    
   
   =
   
    
     
      
       
        min
        ⁢
        
         {
         
          
           N
           1
           ′
          
          ,
          
           N
           2
           ′
          
         
         }
        
       
       -
       
        N
        
         f
         -
         IGBT
        
       
      
      
       min
       ⁢
       
        {
        
         
          N
          1
          ′
         
         ,
         
          N
          2
          ′
         
        
        }
       
      
     
     ⨯
     100
    
    ⁢
    %
   
  
  ,, wherein Nf-IGBT is an IGBT lifetime which is obtained by using the simultaneous failure probability model; and
S3.3: establishing the coupling function relation between ΔNf-IGBT and ΔN through fitting by treating the difference percentage between the lifetime of the solder layer and the lifetime of the bonding wire as the input and treating the lifetime change rate before coupling and after coupling as the output.