Method and apparatus for filling a mask with solder paste
OwnerJohn T. Mackayinventor
Life of this patent
Estimating the term…
Abstract
Method and apparatus for filling (printing) cells of a mask with solder paste. A first (flood) blade is disposed a distance above a front surface of the mask, moves a glob of solder paste across the surface of the mask. The first blade is followed by a second (cleaning) blade which is in contact with the surface of the mask and which advances across the surface of the mask to remove residual solder paste from the surface of the mask. The distance between the first blade and the mask is on the order of a few (2-5) times the average particle size in the solder paste. The first blade may be plastic. The second blade is preferably non-compliant, such as metal. Profiles for the two blades are disclosed. A method printing multiple masks with multiple sets of blades is disclosed.
Claims18
Method of filling cells of a mask with a viscous material, comprising:
- with a first blade disposed a distance above a front surface of the mask, and with a glob of viscous material in front of the first blade, advancing the first blade across the surface of the mask;
- and
- with a second blade in contact with the surface of the mask, advancing the second blade across the surface of the mask to remove residual viscous material from the surface of the mask.
A set of blades for filling cells of a mask with solder paste, comprising:
- a first, flood blade which is generally rectangular in cross-section, having a leading surface, a trailing which is generally parallel to the leading surface, and a side edge which is generally perpendicular to the leading and trailing surfaces and which, in use, is disposed opposing the mask, wherein the side edge is chamfered (beveled) so as to present a sloping surface for pushing the solder paste down into the cells of the mask when the first blade is moved across the mask;
- and
- a cleaning blade for clearing residual solder paste from the mask.
Method of printing a sequence of masks with solder paste, comprising:
- positioning a first mask between a first print landing areas and a second print landing area;
- with a first set of blades parked at the first landing area, disposing a glob of solder paste in front of the first set of blades;
- advancing the first set of blades advances across the towards the second print landing area to fill the cells of the first mask with solder paste;
- continuing to advance the first set of blades until it is entirely beyond the mask, and residual solder paste that is being pushed forward is on the second print landing area;
- then, retracting the first set of blades;
- removing the first mask, and positioning a second mask between the two print landing areas;
- with a second set of blades, starting from the second print landing area, pushing the solder paste entirely across the second mask to fill the cells of the second mask, until residual solder paste that is being pushed forward is on the first print landing area.
Method of filling cells of a mask with a viscous material, comprising:
- disposing a quantity of the viscous material on a surface of the mask;
- bringing a first blade to a distance of a few mils from the surface of the mask;
- contacting the mask with a cleaning blade;
- advancing the print blade across the surface of the mask to fill the cells;
- and
- advancing the cleaning blade across the surface of the mask, behind the print blade.
Method for forming solder balls on a substrate having a plurality of pads on a surface thereof, comprising:
- providing a mask having a plurality of cells;
- filling the cells of the mask with solder paste by filling the cells of the mask with a flood blade spaced a distance from the surface of the mask and moving across the mask followed by a cleaning blade in contact with the surface of the mask and moving across the mask;
- with the mask disposed on the surface of the substrate, reflowing the solder material;
- and separating the substrate from the mask.
Dependencies are inferred from the claim text.