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Causes and Cures of Incomplete pad prints
Process Defect Guide


Incomplete pad prints

Incomplete pad prints are normally a function of the paste and stencil aperture.

The example is on a 0603 pad, which should not be particuarly demanding for the printing process or the paste technology of today.

The incomplete print is more likely related to the poor cleaning of the stencil after previous use. The paste has probably been left in the stencil aperture, it has dried and when the stencil is used again the complete pad print from the aperture is not possible.

The same problem can occur with poor paste release from a stencil aperture but not from such a coarse pitch part. On finer pitch components paste remains held in the stencil aperture and can be a paste stencil issue.

 
References
  1. By Bob Willis.,
    Bob Willis is a process engineering consultant with Electronic Presentation
    Services, Chelmsford, England; (44) 01245 351502; fax: (44) 01245 496123
  2. For more info aboutprinting and stencils look at the Articles / Newsletter:
    (printing)


Circuits Assembly. (Process Defect Clinic)

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