Surface modification of solder paste stencils
The present disclosure relates to surface modification of solder paste stencils to provide improved adhesion of a functional coating. The disclosed surface modifications include laser structuring, plasma treatments, and primers. Methods of using the solder paste stencils are further disclosed.
1 . A method of modifying one or more surfaces of a stencil, the method comprising:
forming apertures in the one or more surfaces with a first laser;
ablating the one or more surfaces and/or one or more aperture walls of the formed apertures with laser radiation from a second laser, wherein the laser radiation comprises a wavelength of about 1064 nm;
treating the one or more surfaces with a plasma treatment process to form a functionalized primer layer; and
applying a hydrophobic and oleophobic coating;
wherein the step of ablating forms structures and removes contaminants present in the one or more surfaces and/or the one or more aperture walls of the formed apertures, wherein the structures in the one or more surfaces and/or the one or more aperture walls of the formed apertures comprise a three-dimensional pattern, wherein the three-dimensional pattern comprises an orthogonal grid of divots, and wherein each divot is spaced apart by about 50 μm to 150 μm in each coordinate direction of each divot.
2 . The method according to claim 1 , wherein the stencil is a Surface Mount Technology (“SMT”) stencil.
3 . The method according to claim 1 , wherein the structures have a depth of about 1 micron or less.
4 . The method according to claim 1 , wherein the one or more surfaces of the stencil is a working surface of the stencil.
5 . The method according to claim 1 , wherein the laser radiation is swept across the one or more surfaces and/or the one or more aperture walls of the formed apertures by moving a laser or by use of steering optics.
6 . The method according to claim 1 , wherein the laser radiation is swept across the one or more surfaces and/or the one or more aperture walls of the formed apertures by moving the stencil.
7 . The method according to claim 1 , wherein the laser radiation is focused to an area of about 1×10 −10 m 2 to about 5×10 −10 m 2 .
8 . The method according to claim 1 , wherein the laser radiation is generated by a pulsed fiber laser.
9 . The method according to claim 8 , wherein the pulsed fiber laser has an energy of about 0.25 mJ per pulse.
10 . The method according to claim 1 , wherein the hydrophobic and oleophobic coating is formed from a composition comprising a silica-based polymer and a compound comprising a fluorine containing moiety.
11 . The method according to claim 1 , wherein the stencil exhibits improved resistance to chipping during operation as compared to a stencil that has not had one or more surfaces and/or the one or more aperture walls of the formed apertures ablated with laser radiation.
12 . The method according to claim 1 , wherein the first laser is the same as the second laser.
13 . The method according to claim 1 , wherein the first laser is different than the second laser.