JP2009016699A - Wiring circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring circuit board in which an electrical short circuit between a plurality of terminals are fully prevented and a space between the adjacent terminals is reduced, and its manufacturing method. <P>SOLUTION: A base insulating layer 2 is formed on a support substrate 1. A plurality of concave portions G are formed on the base insulating layer 2. Then, a conductor layer 3 of a predetermined pattern is formed on the base insulating layer 2. A plated layer 4 composed of gold is formed in such a manner that a portion of the conductor layer 3 positioned in the concave portion G is covered with the plated layer. Therefore, a terminal T constituted of the plated layer 4 and the conductor layer 3 is formed in the concave portion G of the base insulating layer 2. A cover insulating layer 5 is formed on the base insulating layer 2 except a region with a predetermined width from the concave portion G and both end sides thereof. A dam 5D is formed between two terminals T. Further, a groove gr extending in a direction in parallel with the terminal T from an opening H is formed on the upper surface of the cover insulating layer 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printed circuit board and a method for manufacturing the same.

  A wired circuit board such as a flexible wired circuit board is generally formed by forming a wiring pattern made of a conductor layer on an insulating layer, and is used in various electronic devices.

A plurality of connection terminals are provided on the printed circuit board. The plurality of connection terminals of the printed circuit board are electrically connected to the plurality of connection terminals of the electronic component or another printed circuit board. Solder is used for connection between each connection terminal of the printed circuit board and each connection terminal of the electronic component or another printed circuit board (see, for example, Patent Document 1).
JP 2001-345547 A

  In recent years, along with miniaturization and high integration of electronic devices, miniaturization of wiring patterns on a printed circuit board has been promoted. Accordingly, the interval between adjacent connection terminals is reduced.

  However, when the interval between adjacent connection terminals of the printed circuit board is reduced, when connecting one connection terminal of the printed circuit board and one connection terminal of the electronic component by solder, There is a case where an electrical short circuit occurs between adjacent connection terminals.

  An object of the present invention is to provide a printed circuit board that can sufficiently prevent an electrical short circuit between a plurality of terminal portions and reduce the interval between adjacent terminal portions, and a method for manufacturing the same. .

  (1) A printed circuit board according to a first invention covers a base insulating layer having a first surface, a plurality of conductor patterns formed on the first surface of the base insulating layer, and a plurality of conductor patterns. And a cover insulating layer formed on the first surface of the base insulating layer, the base insulating layer has a plurality of recesses provided corresponding to the plurality of conductor patterns on the first surface, Each of the plurality of conductor patterns has a terminal portion disposed in the corresponding concave portion and a wiring portion disposed outside the concave portion, and the cover insulating layer has a plurality corresponding to the plurality of concave portions of the base insulating layer. The conductor pattern has a plurality of openings so that the terminal portions are exposed, and a partition portion is provided between adjacent openings.

  In this printed circuit board, the terminal portions of the plurality of conductor patterns are exposed in the plurality of openings of the insulating cover layer formed on the first surface of the insulating base layer. A partition portion is formed between adjacent openings.

  To the plurality of terminal portions of the wired circuit board, electronic components or the plurality of connection terminals of another wired circuit board are respectively connected using solder. At the time of this connection, molten solder is accommodated in each opening. Here, since the partition portion is formed between the adjacent openings, it is possible to prevent the molten solder from flowing between the adjacent openings.

  In addition, the plurality of terminal portions are respectively disposed in corresponding recesses provided in the base insulating layer. Thereby, since the upper surface of a terminal part exists in the low position in an opening part, a space is formed in the upper part of the terminal part in an opening part. This sufficiently prevents the molten solder from overflowing outside the opening.

  As a result, it is possible to reduce an interval between adjacent terminal portions while sufficiently preventing an electrical short circuit between the plurality of terminal portions.

  (2) The insulating cover layer may have a plurality of grooves extending outward from the edges of the plurality of openings.

  In this case, when the wiring circuit board is connected to an electronic component or another wiring circuit board, even if there is a large amount of solder melted in each opening, the solder overflowing from each opening will start from the edge of each opening. It flows into the groove. This prevents molten solder from flowing into the adjacent opening. As a result, a short circuit between adjacent terminal portions is reliably prevented.

  (3) The starting point of each of the plurality of grooves may be located between the terminal portion and the partition portion.

  In this case, when the wiring circuit board is connected to an electronic component or another wiring circuit board, even if there is a large amount of molten solder in each opening, the solder overflowing from each opening to the adjacent opening is a terminal. Smoothly flows into the groove between the part and the partition part.

  This reliably prevents the molten solder from flowing between adjacent openings. As a result, a short circuit between adjacent terminal portions is sufficiently and reliably prevented.

  (4) A method for manufacturing a printed circuit board according to a second invention includes a step of forming a plurality of recesses on the first surface of the base insulating layer, a terminal portion disposed in the plurality of recesses, and a plurality of recesses outside Forming a plurality of conductor patterns having a wiring portion disposed on the base insulating layer; forming a cover insulating layer on the first surface of the base insulating layer so as to cover the plurality of conductor patterns; Forming a plurality of openings in the insulating cover layer so that the terminal portions of the plurality of conductor patterns are respectively exposed and have a partition between adjacent openings.

  In this method of manufacturing a printed circuit board, a plurality of recesses are formed on the first surface of the base insulating layer, and a plurality of terminals having terminal portions disposed in the plurality of recesses and wiring portions disposed outside the plurality of recesses are provided. Are formed on the insulating base layer. Then, a cover insulating layer is formed on the first surface of the base insulating layer so as to cover the plurality of conductor patterns, so that the terminal portions of the plurality of conductor patterns are respectively exposed and have a partition portion between adjacent openings. A plurality of openings are formed in the insulating cover layer.

  In the printed circuit board thus manufactured, the terminal portions of the plurality of conductor patterns are exposed in the plurality of openings of the insulating cover layer formed on the first surface of the insulating base layer. A partition portion is formed between adjacent openings.

  To the plurality of terminal portions of the wired circuit board, electronic components or the plurality of connection terminals of another wired circuit board are respectively connected using solder. At the time of this connection, molten solder is accommodated in each opening. Here, since the partition portion is formed between the adjacent openings, it is possible to prevent the molten solder from flowing between the adjacent openings.

  In addition, the plurality of terminal portions are respectively disposed in corresponding recesses provided in the base insulating layer. Thereby, since the upper surface of a terminal part exists in the low position in an opening part, a space is formed in the upper part of the terminal part in an opening part. This sufficiently prevents the molten solder from overflowing outside the opening.

  As a result, it is possible to reduce an interval between adjacent terminal portions while sufficiently preventing an electrical short circuit between the plurality of terminal portions.

  (5) You may further provide the process of forming several groove | channels each extended outward from the edge part of several opening part.

  In this way, by forming a plurality of grooves extending outward from the edges of the plurality of openings, the wiring circuit board is melted in each opening when the printed circuit board is connected to an electronic component or another wiring circuit board. Even when the amount of solder is large, the solder overflowing from each opening flows out from the edge of each opening to the groove. This prevents molten solder from flowing into the adjacent opening. As a result, a short circuit between adjacent terminal portions is reliably prevented.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to make the space | interval between adjacent terminal parts small, fully preventing the electrical short circuit between several terminal parts.

[1] Embodiments A printed circuit board and a manufacturing method thereof according to an embodiment of the present invention will be described below with reference to the drawings.

(1-1) Fabrication and Structure of Printed Circuit Board FIGS. 1 to 5 are diagrams showing manufacturing steps of the printed circuit board according to the embodiment of the present invention. 1A to 5A are top views, and FIG. 5B is a longitudinal sectional view taken along line AA in FIG. Moreover, (c) in FIGS. 3-5 is the BB line longitudinal cross-sectional view of (a).

  First, a long support substrate 1 made of stainless steel (SUS) is prepared, and a base insulating layer 2 made of a photosensitive polyimide resin is formed on the upper surface of the support substrate 1. Thereby, as shown in FIG. 1, a laminated substrate 110 in which the base insulating layer 2 is laminated on the support substrate 1 is manufactured.

  As the support substrate 1, a metal material such as aluminum (Al) may be used instead of stainless steel. The thickness of the support substrate 1 is, for example, not less than 10 μm and not more than 60 μm. As the base insulating layer 2, a photosensitive resin material such as a photosensitive epoxy resin may be used instead of the photosensitive polyimide resin. The thickness of the base insulating layer 2 is, for example, not less than 1 μm and not more than 20 μm.

  Next, as shown in FIG. 2, a plurality of recesses G are formed by gradation exposure in the formation region of a terminal portion T (described later) on the upper surface of the base insulating layer 2. In this example, two concave portions G are formed in the substantially central portion of the laminated substrate 110. The two recesses G have the same rectangular shape and extend along the longitudinal direction of the laminated substrate 110.

  In this case, the depth GH of the concave portion G can be adjusted by adjusting the gradation (intensity) of the light applied to the region where the terminal portion T is formed. The depth GH of the recess G is, for example, 2 μm or more and 12 μm or less, and preferably 3 μm or more and 8 μm or less.

  Subsequently, as shown in FIG. 3, a conductor layer 3 made of copper (Cu) having a predetermined pattern is formed on the base insulating layer 2 of the multilayer substrate 110. In this example, the two conductor layers 3 are formed in stripes on the insulating base layer 2 so as to pass through the recesses G, respectively.

  Of the two conductor layers 3, a portion (FIG. 3B) located in the recess G constitutes a part of a terminal portion T (FIG. 4) described later. Moreover, the part (FIG.3 (c)) located out of the recessed part G among the two conductor layers 3 comprises a wiring part.

  The conductor layer 3 on the base insulating layer 2 can be formed using, for example, a semi-additive method, but is not limited thereto, and may be formed using another forming method such as a subtractive method.

  The material of the conductor layer 3 is not limited to copper, and other metals or alloys such as copper alloy, gold (Au), and aluminum may be used.

  The width of the conductor layer 3 is, for example, 10 μm or more and 200 μm or less, and the thickness of the conductor layer 3 is, for example, 6 μm or more and 18 μm or less.

  In the above configuration, a metal layer made of a metal such as copper may be formed between the base insulating layer 2 and the conductor layer 3. In this case, the adhesion between the base insulating layer 2 and the conductor layer 3 is improved.

  Thereafter, as shown in FIG. 4, a plating layer 4 made of gold is formed so as to cover a portion of the conductor layer 3 (FIG. 3B) located in the recess G.

  Specifically, a plating resist is formed so as to cover a portion of the conductor layer 3 positioned outside the recess G, and the plating layer 4 is formed by performing electrolytic plating on the portion of the conductor layer 3 positioned inside the recess G. Form.

  As a result, the terminal portion T composed of the conductor layer 3 and the plating layer 4 is formed in the recess G of the base insulating layer 2.

  Here, the width of the terminal portion T is, for example, 10 μm to 200 μm, and preferably 60 μm to 160 μm. Moreover, the thickness of the terminal part T is 6 micrometers or more and 18 micrometers or less, for example, and it is preferable that they are 10 micrometers or more and 15 micrometers or less.

  In this example, the two terminal portions T are arranged in parallel at a predetermined interval. An interval TD between these two terminal portions T is, for example, 40 μm or more and 230 μm or less, and preferably 100 μm or more and 170 μm or less.

  The plating layer 4 is not limited to gold plating, and may be formed by nickel (Ni) plating, or may be formed by laminating gold plating and nickel plating.

  Next, as shown in FIG. 5, the insulating cover layer 5 is formed on the insulating base layer 2 except for each recess G and regions having a constant width from both sides thereof. As the insulating cover layer 5, as in the insulating base layer 2, a photosensitive resin such as a photosensitive polyimide resin or a photosensitive epoxy resin can be used.

  Here, a part of the insulating cover layer 5 extends in parallel with the terminal portion T on the region between the two terminal portions T. In the following description, the portion of the insulating cover layer 5 extending between the two terminal portions T is referred to as a dam 5D.

  Thereby, each terminal portion T extends into the opening H formed in the insulating cover layer 5.

  As the insulating cover layer 5, an insulating epoxy resin or the like may be used instead of the photosensitive polyimide film. The insulating cover layer 5 has a thickness of, for example, 2 μm or more and 8 μm or less.

  Further, the width DW of the dam 5D located between the two terminal portions T is, for example, 10 μm or more and 100 μm or less, and preferably 30 μm or more and 80 μm or less. Further, the height 5DH of the dam 5D is, for example, not less than 1 μm and not more than 10 μm, and preferably not less than 2 μm and not more than 7 μm. In particular, the height 5DH of the dam 5D is set so that the terminal portion T does not protrude from the cover insulating layer 5 and the dam 5D.

  A groove gr extending in the direction parallel to the terminal portion T from the opening H is formed on the upper surface of the insulating cover layer 5 by gradation exposure. The groove gr is formed in the same manner as the concave portion G described above.

  Here, the groove gr is formed so as to extend from between the terminal portion T and the dam 5D in a direction orthogonal to the axis of the two adjacent terminal portions T. The depth of the groove gr is, for example, not less than 0.5 μm and not more than 9.5 μm, and preferably not less than 1 μm and not more than 7 μm. Further, the width of the groove gr is, for example, 10 μm or more and 100 μm or less, and more preferably 30 μm or more and 80 μm or less.

  In the above manufacturing method, it has been described that the opening H and the groove gr are simultaneously formed in the insulating cover layer 5, but the opening H and the groove gr may be formed in separate steps.

  As described above, the printed circuit board 120 according to the present embodiment is completed. The wired circuit board 120 can be used as a suspension board with a circuit, for example. The suspension board with circuit is used in, for example, a hard disk drive device, and is a wired circuit board for positioning a magnetic head on a desired track of a magnetic disk.

(1-2) Effect In the printed circuit board 120 according to the present embodiment, the terminal portion T is exposed in the opening H in the insulating cover layer 5 formed on the insulating base layer 2. A dam 5D is formed between the two terminal portions T.

  When electronic components are mounted on the printed circuit board 120, the two connection terminals of the electronic components are connected to the two terminal portions T of the wired circuit board 120 using solder. At the time of this connection, the melted solder is accommodated in the opening H formed for each terminal portion T.

  Here, since the dam 5D is formed between the adjacent terminal portions T, it is possible to prevent the molten solder from flowing between the adjacent terminal portions T.

  Further, the plurality of terminal portions T are respectively disposed in the corresponding concave portions G provided in the base insulating layer 2. Thereby, since the upper surface of the terminal portion T exists at a low position in the opening H, a space is formed above the terminal portion T in the opening H. This sufficiently prevents the molten solder from overflowing outside the opening H.

  As a result, it is possible to reduce the interval between the adjacent terminal portions T while sufficiently preventing an electrical short circuit between the plurality of terminal portions T.

  Further, a groove gr is formed on the insulating cover layer 5 so as to extend from the end of the opening H between the terminal portion T and the dam 5D. Thereby, even when the amount of molten solder in the opening H of the insulating cover layer 5 is large, the solder overflowing from each opening H is prevented from flowing into the adjacent opening H. In this case, as shown by the thick arrows in FIG. 5A, the solder overflowing from each opening H flows out from the opening h to the groove gr. As a result, a short circuit between adjacent terminal portions T is sufficiently and reliably prevented.

  The plurality of terminal portions T of the wired circuit board 120 are not limited to the plurality of connection terminals of the electronic component, and a plurality of connection terminals of other wiring circuit boards, lead wires, and the like can be connected.

(1-3) Correspondence relationship between each component of claim and each part of embodiment Hereinafter, an example of a correspondence between each component of the claim and each part of the embodiment will be described. It is not limited to examples.

  In the said embodiment, the conductor layer 3 is an example of a conductor pattern, the part located outside the recessed part G among the conductor layers 3 is an example of a wiring part, and the dam 5D is an example of a partition part.

  As each constituent element in the claims, various other elements having configurations or functions described in the claims can be used.

[2] Investigation of mounting of electronic components on printed circuit board The inventor manufactured the printed circuit board 120 according to the example and the printed circuit board according to the comparative example, and used solder for each printed circuit board to perform electronic The parts were mounted.

(2-1) Embodiment FIG. 6A is a longitudinal sectional view of the terminal portion T of the wired circuit board 120 of the embodiment, and FIG. 6B is a longitudinal sectional view of the wiring section of the wired circuit board 120 of the embodiment. FIG. In the example, the printed circuit board 120 was manufactured based on the method for manufacturing the printed circuit board 120 described in the above embodiment.

  In the printed circuit board 120 of FIG. 6, the thickness a1 of the base insulating layer 2 is 10 μm, the depth a2 of the recess G is 7 μm, and the thickness a3 of the cover insulating layer 5 is 4 μm.

  Further, the width a4 of the terminal portion T composed of the conductor layer 3 and the plating layer 4 is 110 μm, and the interval a5 between the two terminal portions T is 135 μm. The width a6 of the dam 5D located between the two terminal portions T is 55 μm, and the distance a7 between the terminal portion T and the dam 5D is 40 μm. Further, the depth b1 of the groove gr formed in the insulating cover layer 5 is 5 μm, and the width b2 of the groove gr is 40 μm.

(2-2) Comparative Example FIG. 7A is a longitudinal sectional view of the terminal portion T of the printed circuit board of the comparative example, and FIG. 7B is a longitudinal sectional view of the wiring portion of the printed circuit board 200 of the comparative example. It is. In the comparative example, the printed circuit board 200 was produced by the same method as in the example except that the recess G, the dam 5D, and the groove gr were not provided.

(2-3) Evaluation The two terminal portions T of the printed circuit board 120 of the example are brought into contact with the two connection terminals of the electronic component covered with solder, and the solder of each connection terminal of the electronic component is melted. Thus, electronic components were mounted on the printed circuit board 120.

  In this case, the molten solder was prevented from flowing between the adjacent terminal portions T, and a short circuit between the adjacent terminal portions T due to the molten solder was reliably prevented.

  Further, of the molten solder, excess solder overflowing from the opening H of the cover insulating layer 5 flows out from the opening H into the groove gr formed in the cover insulating layer 5.

  This prevents the solder overflowing from the two openings H formed corresponding to the adjacent terminal portions T from coming into contact with each other. As a result, a short circuit between adjacent terminal portions T due to molten solder was reliably prevented.

  On the other hand, electronic components were mounted on the printed circuit board 200 of the comparative example in the same manner as the printed circuit board 120 of the example. In this case, the molten solder flowed between the adjacent terminal portions T, and a short circuit occurred due to the molten solder between the adjacent terminal portions T. Further, excess solder overflowing from the opening H of the insulating cover layer 5 flowed out so as to spread from the opening H.

  As a result, the recess G is formed in the insulating base layer 2, the dam 5D is formed between the adjacent openings H of the insulating cover layer 5, and the groove gr extending from the edge of the opening H on the insulating cover layer 5 is formed. It was found that the electrical short circuit between the plurality of terminal portions T can be sufficiently prevented by forming.

  The present invention can be used for various electric devices or electronic devices.

It is a figure which shows the manufacturing process of the printed circuit board which concerns on one embodiment of this invention. It is a figure which shows the manufacturing process of the printed circuit board which concerns on one embodiment of this invention. It is a figure which shows the manufacturing process of the printed circuit board which concerns on one embodiment of this invention. It is a figure which shows the manufacturing process of the printed circuit board which concerns on one embodiment of this invention. It is a figure which shows the manufacturing process of the printed circuit board which concerns on one embodiment of this invention. It is a longitudinal cross-sectional view which shows the printed circuit board of an Example. It is the top view and longitudinal cross-sectional view which show the printed circuit board of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 2 Base insulating layer 3 Conductor layer 5 Cover insulating layer 120 Printed circuit board G Concave part T Terminal part H Opening 5D Dam gr Groove

Claims (5)

A base insulating layer having a first surface;
A plurality of conductor patterns formed on the first surface of the base insulating layer;
A cover insulating layer formed on the first surface of the base insulating layer so as to cover the plurality of conductor patterns;
The base insulating layer has a plurality of recesses provided on the first surface corresponding to the plurality of conductor patterns,
Each of the plurality of conductor patterns has a terminal portion disposed in a corresponding recess, and a wiring portion disposed outside the recess,
The insulating cover layer has a plurality of openings so that the terminal portions of the plurality of conductor patterns are respectively exposed corresponding to the plurality of concave portions of the insulating base layer, and is partitioned between adjacent openings. A printed circuit board having a portion. The printed circuit board according to claim 1, wherein the insulating cover layer has a plurality of grooves extending outward from the edges of the plurality of openings. 3. The printed circuit board according to claim 2, wherein the starting point of each of the plurality of grooves is located between the terminal portion and the partition portion. Forming a plurality of recesses on the first surface of the base insulating layer;
Forming a plurality of conductor patterns on the base insulating layer having terminal portions disposed in the plurality of recesses and wiring portions disposed outside the plurality of recesses;
Forming a cover insulating layer on the first surface of the base insulating layer so as to cover the plurality of conductor patterns;
And a step of forming a plurality of openings in the insulating cover layer so that the terminal portions of the plurality of conductor patterns are respectively exposed and have a partition between adjacent openings. Manufacturing method. 5. The method of manufacturing a printed circuit board according to claim 4, further comprising a step of forming a plurality of grooves respectively extending outward from the edges of the plurality of openings.

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