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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


solder paste volume spread

#18541

solder paste volume spread | 3 January, 2002

Hello, I need to know the volume spread of solderpaste after screenprinting fine-pitch paste using a nickelformed screen. It is the end-result that counts , so of course the spread of metalcontent in the paste is important too. Can anyone tell me something more about this? Thanks!

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#18550

solder paste volume spread | 3 January, 2002

Slump is a function of the particular paste you select and the temperature of the paste. Use a slump test like the one that follows to compare fluxes.

Slump Test

Step Process activity 1 Print paste on white ceramic substrate or microscope slides. Use a stencil with 15 to 20 rows of a series of 0.025 by 0.050 inch apertures spaced 0.050, 0.040, 0.025, 0.015, 0.010, 0.010, 0.025, 0.040, 0.050 inches apart. Source of supply: Metal Etching Technology. 2 Inspect the paste at X30 magnification. The shape of the deposit should be a �brick.� Record the pitch that slumping became prevalent. 3 Bake the substrate at 150�C for 2 minutes. 4 Inspect the paste at X30 magnification. There should be no slumping. Record the pitch that slumping became prevalent.

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