I. SQUEEGEE DOWN FORCE PRINTING

Metal Blade recommendation

· On-contact, squeegee down force pressure 10-20

· Off-contact, squeegee down force pressure 10-25

· Should be sufficient to wipe stencil clean

· Abnormal stencil wear

· Solder paste scooping

· Solder paste squeezing out on back side of stencil - solder balls may develop as a result

Depending upon blade edge angles, blade hardness and blade material type, it may have some effect on general recommendation.

· On-contact, squeegee down force pressure 10-15

· Off-contact, squeegee down force pressure 10-25

· Should be sufficient to wipe stencil clean

Non-metal blade excess down force may cause:

· Abnormal stencil wear

· Solder paste scooping

· Solder paste squeezing out on back side of stencil - solder balls may develop as a result

II. ON-CONTACT OR OFF-CONTACT PRINTING:

On-contact More smudge (vacuum hold-down)

Off-contact Large stencil or screens may need more snap-off

General snap-off range: 1 mil. - 25 mils.

Facilitates paste release from stencil or screen

Fine pitch: 12 mils. - 20 mils. 0.5 - 1.5 inch/second

Standard pitch: 20 mils. - 50 mils. 1.5 - 4.5 inch/second

· Paste viscosity will have some affect on printer head squeegee speed.

· Slower speeds will generally yield more consistent print height.

· As stencil thickness increases squeegee head speed should decrease.

· Stainless steel, brass or nickel plated

· 8 -10mil. 50 mils. - 25 mils. pitch

· 6 - 8 mils. 35 mils. - 20 mils. pitch

· 3 - 5 mils. 25 mils. - 12 mils. pitch

· paste viscosity

· squeegee speed

· snap-off distance

· paste temperature

· size of mesh opening

· stencil tension

· distance from squeegee edge to stencil frame

Before start paste temperature should be room temperature. Paste should be stirred before set-up or used on the printer before making final setting.