smt kapton stencils
DESCRIPTION
This deck discusses how and when it is appropriate to use Kapton(TM) stencils for PCB prototyping. It also discusses the advantages of Kapton vs Mylar.TRANSCRIPT
Kapton™ Prototype Stencils
When Appropriate?
Fewer than 10 prints 0.8mm pitch or greater geometries Enough distance between
apertures Smaller than 6 x 6” print area
Why Kapton™?
Excellent heat withstand properties to maintain dimensions
Ability to withstand local heat generated by laser machining to prevent “ridges” from forming and not being coplanar to the board
Type FPC used for stencils best cost/performance
Kapton™ Performance-Limitations Very similar to stainless to 0.8mm pitch 95-97% transfer efficiency if hand
printing and 0.8mm or greater For hand printing the “sccoping” effect
is more pronounced If distance between components is too
tight then “smearing” can become pronounced
Kapton™ Stencils at Ultrafine pitch-”smearing”
Why NOT Mylar?
Poor heat withstand properties Used because it is very cheap and
optically opaque for alignment Many different thicknesses “Ridges” near aperture walls
Why NOT Mylar?
Why NOT Mylar?
Kapton Performance-Limitations
“Scooping” of solder paste if too much pressure applied to squeegee
Kapton™ Stencil-More Research
Study of Kapton stencils transfer efficiency vs metal stencils
https://www.smtnet.com/library/files/upload/plastic-vs-metal-stencils.pdf
www.soldertools.net
Where to go?
www.soldertools.net www.stencilsunlimited.com
Professional companies-understand SMT assembly
Check plotsMultiple laser sources