Question of Jim M . :

? What are some of the major causes of tombstoning of small chip SMT components?

? Jim M.
? [log in to unmask]

Answer of Ivo de R. :

Try reading IPC-S-816, SMT Process Guideline and Checklist. 
Some causes mentioned here are :

- movement of the board in reflower
- bad placement of components
- variety in solderability on pads
- bad pad design

I've tried :
- reflowing of the PCB in an other direction (rotate board before reflowing) 
- (with a convection reflow oven) less convection, eas'up on the blowers ! 

Good luck !

***********************************
 Ivo de Rooij
 Process Engineer and Operator
 Surface Mount Assembly
 Fokker Elmo BV
 P.O. Box 75
 4630 AB Hoogerheide
 The Netherlands
 telephone (+31)(0) 164 - 6 17 000
 datafax   (+31)(0) 164 - 6 17 700
 e-mail    [log in to unmask]
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