Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


assembly cleanliness

Views: 866

#58070

assembly cleanliness and ionic testing | 12 February, 2009

i have searched the forum for hours. read all the threads that deals with cleanliness and ionic testing. (http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=40295) (http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=22603) (http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=14197)

i have assemblies that fail from one CM at .4uMhos (~1.25ugr/cm2, ~8ugr/in2, ~.17ppm), that pass from another CM at .27uMhos (~.85ugr/cm2, ~5.5ugr/in2).

is it unreasonable to require a CM that the assemblies (water soluable flux wave and smt, + no clean hand soldering) meet .3uMho's or .9ugr/cm2 or 6ugr/in2?

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JAX

#58083

assembly cleanliness and ionic testing | 13 February, 2009

Many shops require levels for typical component packages on FR-4 or a like substrate to be 2, 9, 15, 1 and 10 mg/in2 for fluoride, chloride, bromide, nitrate, and sulfate respectively. These levels can change for Medical or Automotive.

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#58087

assembly cleanliness and ionic testing | 14 February, 2009

We believe that it's perfectly resonable for you to define the cleanliness that you require. We recommend that you leave it at that and not define the process or materials that your supplier use in meeting that cleanliness level.

Start with a dirty board, end-up with a dirty assembly.

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