# US 2020/0288563 A1 · Display device and method of manufacturing flexible printed circuit board > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0288563 A1 - Document ID: US20200288563A1 - Status: Published application - Kind: A1 - Application number: 16/729,763 - Filed: 2019-12-30 - Published: 2020-09-10 - Earliest claimed: 2019-03-08 - Assignees: Samsung Display Co., Ltd. - Applicants: Samsung Display Co., LTD. - Inventors: Wi Jin NAM; Jong Won MOON - Web page: https://patentgrep.com/patent/US20200288563A1 ## CPC - H05K 1/028: {Bending or folding regions of flexible printed circuits (H05K1/0283 takes precedence)} - H05K 1/0373: {containing additives, e.g. fillers (H05K1/036 takes precedence)} - H05K 1/147: {at least one of the printed circuits being bent or folded, e.g. by using a flexible printed circuit (H05K1/148 takes precedence)} - H05K 3/0041: {by plasma etching} - H05K 3/285: {Permanent coating compositions} - H05K 3/30: Assembling printed circuits with electric components, e.g. with resistors - H05K 1/189: characterised by the use of flexible or folded printed circuits - H05K 2201/0209: Inorganic, non-metallic particles - H05K 2201/056: Folded around rigid support or component - H05K 2201/10128: Display - H05K 2203/095: Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes - H10K 59/131: Interconnections, e.g. wiring lines or terminals - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES ## Abstract A display device includes a display panel including a display surface and a rear surface opposite to each other; and a flexible printed circuit board attachable to the display panel at the rear surface of the display panel. The flexible printed circuit board includes a conductive layer, a passivation layer defining an outer surface of the flexible printed circuit board, and a base film between the conductive layer and the passivation layer, the outer surface includes a first region at which the rear surface of the display panel is attachable to the flexible printed circuit board and a second region at which the rear surface of the display panel is not attached to the flexible printed circuit board, and the first region has greater surface roughness than the second region. ## Claims ### Claim 1 A display device comprising: a display panel including a display surface and a rear surface which is opposite to the display surface; and a flexible printed circuit board attachable to the display panel at the rear surface of the display panel, wherein the flexible printed circuit board includes a conductive layer, a passivation layer defining an outer surface of the flexible printed circuit board, and a base film between the conductive layer and the passivation layer, the outer surface includes a first region of the passivation layer at which the rear surface of the display panel is attachable to the flexible printed circuit board and a second region of the passivation layer at which the rear surface of the display panel is not attached to the flexible printed circuit board, and the first region of the passivation layer has a greater surface roughness than the second region of the passivation layer. ### Claim 2 (depends on 1) The display device of claim 1, further comprising a first adhesive attachable to the display panel and to the passivation layer at the first region thereof ### Claim 3 (depends on 2) The display device of claim 2, wherein an overlapping area of the first adhesive and the first region of the passivation layer is larger than an overlapping area of the first adhesive and the second region of the passivation layer. ### Claim 4 (depends on 3) The display device of claim 3, wherein within the flexible printed circuit board, the passivation layer includes a resin layer and fillers which are dispersed in the resin layer. ### Claim 5 (depends on 4) The display device of claim 4, wherein at the first region of the passivation layer, the fillers are projected from the resin layer to be exposed outside of the resin layer. ### Claim 6 (depends on 5) The display device of claim 5, wherein attachment of the first adhesive at the first region of the passivation layer disposes the first adhesive in contact with both the resin layer and with the fillers which are exposed outside of the resin layer. ### Claim 7 (depends on 6) The display device of claim 6, wherein within the passivation layer of the flexible printed circuit board, the resin layer includes an organic material, and the fillers include an inorganic material. ### Claim 8 (depends on 2) The display device of claim 2, wherein the first adhesive includes a first adhesive layer at which the first adhesive is attachable to the passivation layer at the first region thereof, a second adhesive layer at which the first adhesive is attachable to the display panel, and a first base layer between the first adhesive layer and the second adhesive layer, and an adhesive strength of the first adhesive layer is greater than an adhesive strength of the second adhesive layer. ### Claim 9 (depends on 8) The display device of claim 8, further comprising a first release layer removably attachable to the second adhesive layer, wherein an adhesive strength between the passivation layer and the first adhesive layer is greater than an adhesive strength between the first release layer and the second adhesive layer. ### Claim 10 (depends on 1) The display device of claim 1, wherein an average thickness of the passivation layer at the first region thereof is less than an average thickness of the passivation layer at the second region thereof. ### Claim 11 (depends on 10) The display device of claim 10, wherein the first region of the passivation layer is a plasma-etched region of the passivation layer. ### Claim 12 (depends on 1) The display device of claim 1, wherein at the first region, the passivation layer defines a depression recessed from the outer surface at the second region, the depression is defined by a bottom surface and side surfaces which connect the bottom surface and the outer surface at the second region to each other, and a surface roughness of the passivation layer at the bottom surface of the depression is greater than a surface roughness of the side surfaces of the depression. ### Claim 13 A method of manufacturing a flexible printed circuit board, the method comprising: providing a base film, a passivation layer, and a conductive layer which is between the base film and passivation layer, wherein the providing the passivation layer comprises: providing a resin material layer in which fillers are dispersed, on the conductive layer, plasma-etching the resin material layer, at a first region of the resin material layer, while masking the resin material layer from the plasma etching, at a second region of the resin material layer, and curing the resin material layer to provide a resin layer of the passivation layer in which the fillers are dispersed. ### Claim 14 (depends on 13) The method of claim 13, wherein the plasma-etching of the resin material layer at the first region thereof exposes the fillers at the first region to outside the resin material layer at the first region, and the curing of the resin material layer provides the resin layer of the passivation layer including: a first region which has been plasma-etched, from the first region of the resin material layer which has been plasma-etched, and a second region from the second region of the resin material layer. ### Claim 15 (depends on 14) The method of claim 14, further comprising: attaching a first adhesive and a first release layer to the first region of the resin layer of the passivation layer; attaching a second adhesive and a second release layer to the second region of the resin layer of the passivation layer; removing the first release layer from the first adhesive, by which the first adhesive remains attached to the first region of the resin layer of the passivation layer; and removing the second adhesive together with the second release layer from the second region of the resin layer of the passivation layer. ### Claim 16 (depends on 15) The method of claim 15, wherein the attaching the first adhesive and the first release layer to the first region of the resin layer of the passivation layer, comprises attaching the first adhesive to the fillers which are exposed outside of the resin layer at the first region of the resin layer of the passivation layer. ### Claim 17 (depends on 15) The method of claim 15, wherein the first adhesive includes a first adhesive layer at which the first adhesive is attachable to the resin layer at the first region thereof, a second adhesive layer at which the first adhesive is attachable to a display panel, and a first base layer between the first adhesive layer and the second adhesive layer, and an adhesive strength of the first adhesive layer is greater than an adhesive strength of the second adhesive layer. ### Claim 18 (depends on 17) The method of claim 17, wherein the second adhesive includes a third adhesive layer at which the second adhesive is attachable to the resin layer at the second region thereof, a second adhesive layer facing the first adhesive layer, and a second base layer between the third adhesive layer and the fourth adhesive layer, and an adhesive strength of the third adhesive layer is less than an adhesive strength of the fourth adhesive layer. ### Claim 19 (depends on 18) The method of claim 18, wherein the adhesive strength of the first adhesive layer is greater than the adhesive strength of the third adhesive layer. ### Claim 20 (depends on 19) The method of claim 19, wherein an adhesive strength between the second adhesive layer and the first release layer is less than an adhesive strength between the fourth adhesive layer and the second release layer.