Patent ID: 6988652

Claim:
A method for printing solder paste on a conductive pad of a printed wiring board, the method comprising: providing a printed wiring board having at least one conductive contact pad having a surface suitable for adhesion of solder paste to provide a physical and electrical coupling between the printed wiring board and an electronic component; providing a stencil having a board side and a fill side, wherein the stencil includes sidewalls that define at least one aperture, the sidewalls being coated with parylene or its homologues and the coating having a surface energy lower than that of the stencil, the aperture extending from the board side to the fill side, the cross-section of the aperture at the board side having a profile that fits within the profile of the surface of the contact pad, and the aperture being tapered such that the area of the cross-section of the aperture at the fill side is larger than the area of the cross-section of the aperture at the board side; placing the board side of the stencil in contact with the printed wiring board and aligning the aperture with the contact pad of the printed wiring board; and printing solder paste, in paste form, through the aperture and onto the contact pad, the solder paste adhering to the contact pad.