Source: https://patents.google.com/patent/US7036214?oq=5%2C241%2C671
Timestamp: 2018-02-26 04:24:26
Document Index: 254814882

Matched Legal Cases: ['Application No. 2002', 'arts 105', 'art 105', 'art 105', 'art 105', 'art 105', 'arts 105', 'arts 105']

US7036214B2 - Manufacturing method of rigid-flexible printed circuit board and structure thereof - Google Patents
Manufacturing method of rigid-flexible printed circuit board and structure thereof
US7036214B2
US7036214B2 US10383227 US38322703A US7036214B2 US 7036214 B2 US7036214 B2 US 7036214B2 US 10383227 US10383227 US 10383227 US 38322703 A US38322703 A US 38322703A US 7036214 B2 US7036214 B2 US 7036214B2
US10383227
US20030173105A1 (en )
In a manufacturing method of a rigid-flexible printed circuit board, slits for defining two sides of a removing portion are formed in a part of plural resin films, and the plural resin films are stacked and bonded to form a circuit board. Then, a product portion is cut from the circuit board. Before the bonding, a separation sheet is disposed between predetermined adjacent layers of the plural resin films to separate the removing portion from a residual portion of the product portion. Accordingly, while the product portion is cut from the circuit board, the removing portion is separated from the product portion, because the removing portion are defined by the separation sheet, the slits, and a cutting outline of the product portion.
This application relates to and incorporates herein by reference Japanese Patent Application No. 2002-62397 filed on Mar. 7, 2002.
The present invention relates to a rigid-flexible printed circuit board and a manufacturing method thereof. More particularly, the rigid-flexible printed circuit board is manufactured by using plural printed circuit films with slits.
A multi-layer printed circuit board, which has different thickness in each portion, is known as a rigid-flexible printed circuit board. The rigid-flexible printed circuit board is composed of a rigid board portion and a flexible board portion. For example, the rigid board portion is composed from a five-layer printed circuit board, and is used for mounting high-density printed circuit. The flexible board portion is composed, for example, from a four-layer printed circuit board, and is flexible. The flexible board portion is made of polyimide resin, and the rigid board portion is made of epoxy resin. In a related art, the rigid board portion and the flexible board portion are formed individually. Then, the rigid board portion and the flexible board portion are bonded and electrically connected to each other so that the rigid-flexible printed circuit board is formed. This method of manufacturing the rigid-flexible printed circuit board according to the related art is very complicated, and the structure of the rigid-flexible printed circuit board is also complicated.
The present invention has an object to simplify a method of manufacturing a rigid-flexible printed circuit board. Moreover, the present invention has another object to provide a rigid-flexible printed circuit board with a simple structure.
As shown in FIGS. 1A to 1H, a multi-layer printed circuit board 100 is manufactured. First, a conductive foil is formed on one side surface of a resin film 23. Then, the conductive foil on the resin film 23 is etched to have a conductive circuit 22 with a predetermined pattern so that a one-side printed film 21 is formed. In the first embodiment, for example, the conductive foil is composed of a copper foil having the thickness of 18 μm. The resin film 23 is composed of thermoplastic resin, which is made of polyether ether ketone resin (i.e., PEEK resin) and polyether imide resin (i.e., PEI resin). The weight percentage of the PEEK resin is about 35–65 wt. %, and the weight percentage of the PEI resin is about 65–35 wt. %, in accordance with the weight percentage of the PEEK resin. The thickness of the resin film 23 is about 25–75 μm.
After the six one-side printed films 21, 21 a, 21 b are stacked, the stacked films are pressurized and heated in vacuum, so that the stacked films are pressed by upper and lower hot-press plates. The stacked films are heated up to 250–300° C., and are pressurized to 1–10 MPa for 10–20 minutes thereafter. Thereafter, as shown in FIG. 1H, the one-side printed films 21, 21 a, 21 b are bonded to each other. In other words, one-side printed films 21, 21 a, 21 b are thermo-welded together, to be integrated to each other. Moreover, in this pressurizing and heating process, the conductive paste 50 in the hole 24 is sintered and integrated, and becomes a conductive product 51. As a result, in the multi-layer printed circuit board 100, the conductive circuits 22 at different layers are connected to each other.
A mechanism of the bonding between the conductive circuits 22 at different layers is explained as follows. The conductive pastes 50 filled in the holes 24 are made of mixture of the tin particles and the silver particles. When the conductive paste 50 is heated up to 250–350° C. in the hot-pressing process, the tin particles are melted so as to cover the surfaces of the silver particles, because the melting point of the silver is 961° C. and the melting point of the tin particles is 232° C. When the conductive paste 50 is continued to heat, melted tin diffuses from the surface of the silver particles, and an alloy of silver and tin (melting point is 480° C.) is formed. In the hot-pressing process, the conductive paste 50 is also pressurized at 1–10 MPa. Therefore, the conductive product 51 is sintered, and the sintered alloy of silver and tin is formed in the hole 24.
The removing portion 40 is separated from the residual portion of the product portion 60 by the separation sheet 45. However, using the conductive circuit 22, the removing portion 40 can be separated from the residual portion of the product portion 60. As shown in FIG. 5, the conductive circuits 22 b are formed in the residual portion of the product portion 60 on the upper side of the third layer one-side printed film 21 b and on the lower side of the fourth layer one-side printed film 21 b. On the other hand, the conductive circuits 22 a are also formed in the removing portion 40 on the lower side of the second layer film 25 and on the upper side of the fifth layer film 25. In this case, the conductive circuits 22 a, 22 are formed on both sides of the film 25, respectively. That is, the film 25 is a both-side printed film 25. The conductive circuits 22 a on the second and fifth layer both-side printed films 25 and the printed circuits 22 b on the third and fourth layer one-side printed films 21 b are not bonded to each other in the hot-pressing process, because the heating temperature in the hot-pressing process is about 250–350° C. that is lower than the melting temperature of the conductive circuits 22 a, 22 b. Therefore, when the product portion 60 is cut in the cutting process, the conductive circuits 22 a, 22 b are readily separated from each other so that the removing portion 40 is readily separated from the residual portion of the product portion 60. This modification using the both-side printed film 25 can be suitably used for the case where plural removing portions 40 are positioned to scatter in the product portion 60 or the case where the positions of removing portions 40 are different relative to the product portions 60. The conductive circuits 22 a, 22 b provided on the both-side printed films can be formed precisely at predetermined positions, as compared with the separation sheet 45.
In the second embodiment, as shown in FIG. 6A, plural one-side printed films 21, 21 c are stacked to form stacked films, similar to the first embodiment. The one-side printed films 21,21 c are formed by the same manner as the first embodiment. However, the two one-side printed films 21 do not have a slit, and the four one-side printed films 21 c have slits 31 that are positioned at the same position in the films 21 c. No separation sheet is inserted between the one-side printed films 21, 21 c.
After the six one-side printed films 21, 21 c are stacked to form the stacked films, a linked slit 32 with a predetermined width is formed in the first to fourth layer one-side printed films 21 c. Then, the stacked films are pressurized and heated in vacuum. Therefore, as shown in FIG. 6B, the one-side printed films 21, 21 c are bonded to each other. Moreover, in this pressurizing and heating process, a conductive paste 50 in the hole 24 is sintered and integrated to form a conductive product 51. As a result, the multi-layer printed circuit board 102 is formed. After that, as shown in FIG. 7, a product portion 60 is cut from the multi-layer board 102, so that a rigid-flexible printed circuit board is formed. In the second embodiment, the linked slit 32 is formed along the width of the product portion 60, and the thickness of the rigid-flexible printed circuit board at the linked slit 32 is thin. Therefore, the rigid-flexible printed circuit board bends at the linked slit 32. The width of the linked slit 32 is determined such that two edges of the linked slit 32 in the rigid-flexible printed circuit board do not contact when the rigid-flexible printed circuit board bends at the linked slit 32.
Then, the multi-layer printed circuit board 104 is cut to form the product portion 60 in the cutting process, similar to the first embodiment. The removing portion 40 is isolated from the product portion 60, because the slits 30 are provided to enclose the four sidewalls of the removing portion 40 and the separation sheet 45 separates the bottom of the removing portion 40 from the product portion. When the product portion 60 is cut down from the multi-layer printed circuit board 104, the removing portion 40 is simultaneously eliminated from the product portion 60. As a result, a rigid-flexible printed circuit board 104 a is formed, as shown in FIG. 9C. In the third embodiment, the rigid-flexible printed circuit board 104 a has conductive circuits 63, 64 on two sides of the rigid-flexible printed circuit board 104 a.
Then, the board 105 is cut to form a product portion in the cutting process. When the product portion is cut from the board 105, the edge portion of the board 105 is separated into three separated parts 105 a, 105 b, 105 c by the separation sheets 45 a, 45 b.
In the fourth embodiment, the slit 30 has a length in a width direction of the board 105, and the length of the slit 30 is equal to or larger than the width of the product portion. The slit 30 defines the edge of the separated part 105 a, and the separated part 105 b is formed into a L-shape. A conductive circuit land 22 c is disposed at the edge of the separated part 105 b. The conductive circuit land 22 c formed in the separated part 105 b is used for detecting the electric connection between the printed circuits. In other words, the electric connection is checked easily using the conductive circuit land 22 c. The electric connection in the separated parts 105 a, 105 c are readily checked respectively, because the conductive circuits 22 in the separated parts 105 a, 105 c are exposed outside.
In the above-described embodiment, the resin film is made of PEEK resin of 35–65 wt. % and PEI resin of 65–35 wt. %. However, the resin film may be made of other thermoplastic resin, such as mixture of PEEK resin, PEI resin, and non-conductive filler. It is preferred that the resin film may be made of heat-resistant thermoplastic resin, which has a heat-resistance in soldering process or the like and adheres together in the hot-pressing process.
US10383227 2002-03-07 2003-03-07 Manufacturing method of rigid-flexible printed circuit board and structure thereof Active 2023-08-13 US7036214B2 (en)
JP2002062397A JP3820415B2 (en) 2002-03-07 2002-03-07 Structure of the manufacturing method and a printed board of the printed circuit board
JP2002-62397 2002-03-07
US20030173105A1 true US20030173105A1 (en) 2003-09-18
US7036214B2 true US7036214B2 (en) 2006-05-02
ID=27764446
US10383227 Active 2023-08-13 US7036214B2 (en) 2002-03-07 2003-03-07 Manufacturing method of rigid-flexible printed circuit board and structure thereof
US (1) US7036214B2 (en)
JP (1) JP3820415B2 (en)
DE (1) DE10309188B4 (en)
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KONDO, KOJI;TAKEUCHI, SATOSHI;YOKOCHI, TOMOHIRO;AND OTHERS;REEL/FRAME:014093/0954;SIGNING DATES FROM 20030220 TO 20030311