Rob, 

  The viscocity value is given by the solder paste supplier.
    KCPS is a unit used to measure viscocity ( Kilo centipoise ( I am
not sure !!! ))
    The test is done using viscocimeter normally Brookfield or Malcom (
the way of measurement is diferent and the values also )
    The methods are given by the equipment supplier .

   Here in Brazil most of companies use  operator skill to feel if the
solder paste is too much soft or too much hard. They know if we are
going to get shorts ( low viscocity ) or no solder due gloged solder
paste inside stencil apertures( high viscocity). The measure using
equipment requires ambiente temperature control ( normally 24 degree
celcius ). 
   Another fact is that solder paste change their viscocity value during
printing cycle.

 
    

> -----Original Message-----
> From: Rob Watson [SMTP:[log in to unmask]]
> Sent: 22 de Março de 1999 16:31
> To:   [log in to unmask]
> Subject:      [TN] Paste Viscosity
> 
> Boy, I am full of questions today... As you can tell, I am really
> digging into
> the screen printing operations.
> 
> I have one more question, I have a troubleshooting guide for the SMT
> process.
> Actually, a presentation someone gave me from a SMTA meeting about 2
> years ago.
> 
> Anyways, this guide recommends that solder paste viscosity be between
> 1000 KCPS
> +/- 10%.
> Does anyone know what this is?  How would you go about testing to
> verify this?
> What test methods and equipment would you use to do this?
> 
> Thanks again for your support in advance,
> 
> Rob Watson
> Sanmina Corp.
> 
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