# US 8,568,961 B2 · Methods for protecting a die surface with photocurable materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,568,961 B2 - Document ID: US8568961B2 - Status: Granted - Kind: B2 - Application number: 13/130,775 - Filed: 2009-11-25 - Published: 2011-09-22 - Granted: 2013-10-29 - Earliest claimed: 2008-11-25 - Assignees: Lord Corporation - Applicants: Russell A. Stapleton - Inventors: Russell A. Stapleton - Web page: https://patentgrep.com/patent/US8568961B2 ## CPC - H10W 74/476: {Organic materials comprising silicon} - H10W 72/30: Die-attach connectors - H10W 74/012: {of encapsulations on active surfaces of flip-chip devices, e.g. forming underfills} - H10W 74/15: on active surfaces of flip-chip devices, e.g. underfills - H10W 72/856: {Bump connectors and die-attach connectors (bumps embedded in underfills H10W74/15)} - H10W 74/00: Encapsulations, e.g. protective coatings - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract In a first aspect of the present invention, a method for manufacturing a flip chip package is provided comprising the steps of a) providing a chip having electrically conductive pads on an active surface thereof, b) coating at least a portion the chip with a protectant composition comprising a polymerizable component comprising a thermosetting epoxy resin, at least 50 weight percent of a substantially transparent filler having a coefficient of thermal expansion of less than 10 ppm/° C., a photoinitator, and a solvent carrier, wherein the protectant composition comprises a thixotropic index of less than 1.5, c) masking the coated chip to mask areas where vias through the protectant are desired, d) exposing the masked chip to a light source sufficient to partially crosslink the protectant composition in the unmasked areas, e) removing the uncured portions of the protectant composition thereby creating vias through the protectant composition to the electrically conductive pads on the surface of the chip, f) applying an electrically conductive material to the chip through the vias, wherein the electrically conductive material protrudes from the surface of the protectant composition, and g) heating the chip to a temperature sufficient to reflow the electrically conductive material and thermoset the protectant composition. ## Claims ### Claim 1 A method for manufacturing a flip chip package comprising: a) providing a chip having electrically conductive pads on an active surface thereof; b) coating at least a portion the chip with a protectant composition comprising a polymerizable component comprising a thermosetting epoxy resin, at least 50 weight percent of a substantially transparent filler having a coefficient of thermal expansion of less than 10 ppm/° C., a photoinitator, and a solvent carrier, wherein the protectant composition comprises a thixotropic index of less than 1.5; c) masking the coated chip to mask areas where vias through the protectant are desired; d) exposing the masked chip to a light source sufficient to partially crosslink the protectant composition in the unmasked areas; e) removing the uncured portions of the protectant composition thereby creating vias through the protectant composition to the electrically conductive pads on the surface of the chip; f) applying a flux composition in the vias then applying an electrically conductive material to the chip through the vias, wherein the electrically conductive material protrudes from the surface of the protectant composition; g) heating the chip to a temperature sufficient to reflow the electrically conductive material and thermoset the protectant composition. ### Claim 2 (depends on 1) The method of claim 1, wherein in connection with step a) the chip is provided on a temporary substrate which is larger in area than the chip; during step b) at least a portion of the temporary substrate adjacent to the chip is coated with the protectant composition; during steps c) and d) the coated portions of the temporary substrate are masked and exposed, and in step e) any uncured portions of the protectant on the temporary substrate are removed to provide vias through the protectant coating to the temporary substrate. ### Claim 3 (depends on 2) The method of claim 2, further comprising the step of applying an electrically conductive material to the vias of the chip and the vias of the temporary substrate. ### Claim 4 (depends on 3) The method of claim 3, wherein the electrically conductive material applied to the vias of the chip comprises solder and the electrically conductive material applied to the vias of the temporary substrate comprises an electrically conductive paste. ### Claim 5 (depends on 1) The method of claim 1, wherein the electrically conductive material comprises solder balls. ### Claim 6 (depends on 1) The method of claim 1, wherein the substantially transparent filler comprises a coefficient of thermal expansion of less than 2 ppm/° C. ### Claim 7 (depends on 1) The method of claim 1, wherein during step g) the temperature is at least 120° C. ### Claim 8 (depends on 1) The method of claim 1, wherein step e) comprises exposing the chip to a development solution by an impinging spray. ### Claim 9 (depends on 1) The method of claim 1, wherein step b) is accomplished through at least one of spin coating, screen printing, or stencil printing. ### Claim 10 (depends on 1) The method of claim 1 wherein the chip is provided as a plurality of chips comprising a wafer. ### Claim 11 (depends on 10) The method of claim 10, further comprising the step of dicing the wafer to create individual dies. ### Claim 12 (depends on 11) The method of claim 11, wherein during the step of dicing the wafer is aligned through visual means through the protectant composition. ### Claim 13 (depends on 1) The method of claim 1 wherein the coefficient of thermal expansion of the thermoset protectant composition is less than 20 ppm/° C. ### Claim 14 (depends on 1) The method of claim 1, wherein prior to step c) the material is b-staged to form a solid composition by removing the solvent. ### Claim 15 (depends on 14) The method of claim 14, wherein the b-staging is accomplished by heating the coated chip to a temperature not exceeding 120° C. ### Claim 16 (depends on 1) The method of claim 1, wherein the substantially transparent filler comprises fused silica. ### Claim 17 (depends on 1) The method of claim 1, wherein the filler comprises an average particle size of greater than 0.40 microns. ### Claim 18 (depends on 1) The method of claim 1, wherein less than 5 weight percent of the filler particles have a particle size of less than 0.10 microns. ### Claim 19 (depends on 1) The method of claim 1, wherein the polymerizable component of the protectant composition comprises at least 98 percent of an epoxy-based material. ### Claim 20 (depends on 1) The method of claim 1, wherein the polymerizable component of the protectant composition consists essentially of an epoxy-based material. ### Claim 21 (depends on 1) The method of claim 1, wherein the filler has a refractive index, and the epoxy is selected to have a refractive index of within 10 percent of the refractive index of the filler. ### Claim 22 (depends on 1) The method of claim 1, wherein the filler is present in an amount from 50 weight percent to about 90 weight percent based on the total weight of the protectant composition. ### Claim 23 (depends on 1) The method of claim 1, wherein the filler is present in an amount from 65 weight percent to about 75 weight percent based on the total weight of the protectant composition. ### Claim 24 (depends on 1) The method of claim 1, wherein the filler is present at about 70 weight percent based on the total weight of the protectant composition. ### Claim 25 (depends on 1) The method of claim 1, wherein the epoxy resin is present in an amount from 10 weight percent to 50 weight percent based on the total weight of the protectant composition. ### Claim 26 (depends on 1) The method of claim 1, wherein the epoxy resin is present in an amount from 25 weight percent to 35 weight percent based on the total weight of the protectant composition. ### Claim 27 (depends on 1) The method of claim 1, wherein the epoxy resin is present at about 10 weight percent based on the total weight of the protectant composition. ### Claim 28 (depends on 1) The method of claim 1, wherein the solvent is present at about 15 weight percent based on the total weight of the protectant composition. ### Claim 29 (depends on 1) The method of claim 1, wherein the photoinitiator is present in an amount from 0.1 to 2.5 weight percent based on the total weight of the protectant composition. ### Claim 30 (depends on 1) The method of claim 1, wherein the protectant composition is substantially absent polyimides or polyimide precursors. ### Claim 31 (depends on 1) The method of claim 1, wherein the protectant composition is completely free from polyimides or polyimide precursors. ### Claim 32 (depends on 1) The method of claim 1, wherein the protectant composition is substantially absent acrylates.