Card-edge type printed circuit board

Abstract

To enable the electrical insulating layer between the end edge of the substrate terminal end side of the terminal portion and the edge of the substrate to avoid being scraped by sliding contact of the connector terminals, and to suppress the occurrence of insulation and continuity defects.SOLUTION: In a card edge type printed wiring board including a terminal portion 26 provided to the vicinity of the end edge of the base layer 30, a metallic wear resistant layer 28 is provided over the portion of the electrical insulating layer 22 between the end edge 26A on the substrate edge 23 side of the terminal portion 26 and the substrate edge 23, the wear resistant layer 28 is located at a distance G2 from the end edge 26A of the terminal portion 26.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a card-edge type printed wiring board, and more particularly to a metal plate-based card-edge type printed wiring board.

Background Art

[0002] A metal plate-based printed wiring board having a base layer made of a metal such as aluminum, an electrical insulation layer made of a resin or the like laminated on one surface of the base layer, and a conductive pattern made of a copper foil or the like formed on the electrical insulation layer is known (for example, Patent Documents 1 and 2).

[0003] The metal base layer has better heat dissipation than a resin one, but has a relatively large linear expansion coefficient. When thermal expansion and contraction are repeated, stress is applied to the soldering part or the like. Therefore, it is necessary to form the electrical insulation layer soft to relieve the stress caused by thermal expansion and contraction.

[0004] When applying a metal plate-based printed wiring board to a card-edge type printed wiring board, the conductive pattern has a configuration including a terminal portion provided so as to reach near the edge of the substrate (base layer and electrical insulation layer) so that the connector terminal to be connected comes into conductive contact.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] If the terminal portion is provided so as to extend to the edge of the substrate, the distance between the substrate edge-side end of the terminal portion and the exposed end face of the base layer at the substrate edge becomes short, corresponding to the thickness of the electrical insulation layer. This makes it easier for dielectric breakdown due to creepage discharge to occur between the terminal portion and the base layer. To avoid this dielectric breakdown, it is conceivable to terminate the terminal portion near the edge of the substrate (just before the edge) and to set a larger distance between the substrate edge-side end of the terminal portion and the end face of the base layer.

[0007] When the terminal portion terminates near the edge of the substrate, the electrical insulation layer is exposed between the substrate edge end of the terminal portion and the substrate edge. Therefore, when the connector terminal moves from the substrate edge towards the terminal portion during connector installation, and when the connector terminal moves from the terminal portion towards the substrate edge during connector removal, the connector terminal slides against the electrical insulation layer between the substrate edge end of the terminal portion and the substrate edge, causing the electrical insulation layer to be scraped away. This phenomenon is particularly pronounced in substrates where the electrical insulation layer is formed in a soft state.

[0008] If the electrical insulation layer is scraped away, the base layer may be exposed to the outside, potentially leading to insulation failure. Furthermore, debris from the electrical insulation layer can enter the space between the terminal and the connector terminal, causing poor conductivity between the two.

[0009] In view of the above background, the present invention aims to prevent the electrical insulating layer between the terminal portion of the conductive pattern that the connector terminals make conductive contact with and the edge of the substrate from being scraped by the sliding contact of the connector terminals, thereby suppressing the occurrence of insulation failure and conductivity failure in a metal plate-based card edge type printed wiring board. [Means for solving the problem]

[0010] To solve the above problems, one aspect of the present invention provides a card edge type printed wiring board (10) having a metal base layer (20), an electrical insulating layer (22) laminated on one side of the base layer, and a conductive pattern (24) formed on the electrical insulating layer, wherein the conductive pattern includes a terminal portion (26) provided so as to reach the vicinity of the edge (20A) of the base layer so as to make electrical contact with a connector terminal (52), wherein a metal wear-resistant layer (28) is provided on the portion of the electrical insulating layer between the end portion 26A on the edge side of the terminal portion and the edge of the base layer, and the wear-resistant layer is positioned at a distance (G2) from the end portion of the terminal portion.

[0011] According to this embodiment, the wear-resistant layer prevents the electrical insulation layer between the terminal end on the substrate edge side of the terminal portion and the substrate edge from being worn away by the sliding contact of the connector terminal, thereby suppressing the occurrence of insulation failure and conductivity failure.

[0012] In the above embodiment, preferably, the wear-resistant layer extends to the edge.

[0013] According to this embodiment, the electrical insulating layer is reliably prevented from being scraped by the sliding contact of the connector terminals, including the portion of the electrical insulating layer on the edge side.

[0014] In the above embodiment, preferably, the wear-resistant layer terminates at a distance from the edge of the base layer.

[0015] According to this embodiment, the electrical insulation between the base layer and the wear-resistant layer is improved.

[0016] In the above embodiment, preferably, the wear-resistant layer is made of the same conductive material as the terminal portion and has substantially the same thickness.

[0017] According to this embodiment, a separate process for providing the wear-resistant layer is unnecessary, and the upper surface of the terminal portion and the upper surface of the wear-resistant layer become flush.

[0018] In the above aspect, preferably, the terminal portion includes a plurality of terminal portions arranged left and right, and the wear-resistant layer forms a strip-shaped portion extending in the left-right direction, which is provided in common for the plurality of terminal portions.

[0019] According to this aspect, it becomes difficult for the wear-resistant layer to peel off from the electrical insulation layer.

[0020] In the above aspect, preferably, it has an electrically insulating protective layer covering the wear-resistant layer.

[0021] According to this aspect, the electrical insulation of the wear-resistant layer is improved.

[0022] In the above aspect, preferably, the protective layer includes a portion covering a portion near the terminal end portion of the terminal portion.

[0023] According to this aspect, no gap occurs between the terminal end portion of the terminal portion and the protective layer, and the electrical insulation layer is reliably protected.

[0024] In the above aspect, preferably, the protective layer includes a portion covering the end face of the wear-resistant layer on the edge side of the base layer.

[0025] According to this aspect, the electrical insulation of the wear-resistant layer with respect to the base layer is improved.

[0026] In order to solve the above problems, an aspect of the present invention has a metal base layer, an electrical insulation layer laminated on one surface of the base layer, and a conductive pattern formed on the electrical insulation layer. The conductive pattern includes a terminal portion provided so as to reach the vicinity of the edge of the base layer so that a connector terminal can make conductive contact, and is a card edge type printed wiring board. An electrically insulating protective layer is provided on at least a portion of the electrical insulation layer between the terminal end portion on the edge side of the terminal portion and the edge of the base layer.

[0027] According to this embodiment, the protective layer prevents the electrical insulation layer between the terminal end on the substrate edge side of the terminal portion and the substrate edge from being scraped away by the sliding contact of the connector terminal, thereby suppressing the occurrence of insulation failure and conductivity failure.

[0028] In the above embodiment, preferably, the protective layer includes a portion that covers the portion of the terminal near the end portion.

[0029] According to this embodiment, no gap is created between the terminal end and the protective layer, and the protection of the electrical insulation layer is ensured. [Effects of the Invention]

[0030] According to the above embodiment, the electrical insulating layer between the end of the conductive pattern on the substrate edge side of the terminal portion and the substrate edge, which is electrically contacted by the terminal connector terminal on the substrate edge side of the terminal portion, is not scraped away by the sliding contact of the connector terminal, thereby suppressing the occurrence of insulation failure and conductivity failure. [Brief explanation of the drawing]

[0031] [Figure 1] A perspective view illustrating the card edge type printed circuit board and the connector connected thereto according to the present invention. [Figure 2] Enlarged bottom view of the main part of the card edge type printed circuit board of Embodiment 1 [Figure 3] Cross-sectional view along line III-III in Figure 2 [Figure 4] Enlarged bottom view of the main part of the card edge type printed circuit board of Embodiment 2 [Figure 5] Cross-sectional view along VV in Figure 4 [Figure 6] Enlarged bottom view of the main part of the card edge type printed circuit board of Embodiment 3 [Figure 7] Enlarged bottom view of the main part of the card edge type printed circuit board of Embodiment 4 [Figure 8] Cross-sectional view along line VIII-VIII in Figure 7 [Figure 9] Cross-sectional view of the main part of the card edge type printed circuit board of Embodiment 5 [Figure 10] Enlarged bottom view of the main part of the card edge type printed circuit board of Embodiment 6 [Modes for carrying out the invention]

[0032] Hereinafter, an embodiment of the card edge type printed circuit board according to the present invention will be described with reference to the drawings.

[0033] (Embodiment 1) Embodiment 1 of a card edge type printed circuit board and the card edge connector connected thereto will be described with reference to Figures 1 to 3.

[0034] Figure 1 shows a card edge type printed circuit board 10 (hereinafter abbreviated as circuit board 10) and a card edge connector 50 (abbreviated as connector 50) that is removably attached to the edge portion 12 of the circuit board 10. Figure 2 shows an enlarged bottom view of the main part of the card edge type printed circuit board 10 as seen from below. Figure 3 shows a cross-sectional view along line III-III in Figure 2.

[0035] As shown in Figure 3, the wiring board 10 has a base layer 20, an electrical insulating layer 22 laminated on one side of the base layer 20, and a conductive pattern 24 formed on the electrical insulating layer 22.

[0036] The base layer 20 is made of metal, such as an aluminum plate, copper plate, or iron-based metal plate, having the required thickness. The base layer 20 preferably has a thickness of about 1 to 2 mm.

[0037] The electrical insulating layer 22 is laminated over the entire surface of one side of the base layer 20, and its periphery extends to the edge 20A on the edge portion 12 side of the base layer 20. As a result, the edge 20A of the electrical insulating layer 22 and the edge 22A on the edge portion 12 side of the electrical insulating layer 22 are substantially flush. The edge 20A and the edge 22A on the edge portion 12 side of the electrical insulating layer 22 are collectively referred to as the substrate edge 23. The electrical insulating layer 22 is made of an electrically insulating resin such as polyimide or epoxy, and preferably has a uniform layer thickness of about 100 μm. The electrical insulating layer 22 has a considerable hardness with a storage modulus of about 1 GPa or less, and preferably has a considerable hardness with a storage modulus of 0.3 GPa or less.

[0038] The conductive pattern 24 is made of copper foil or the like formed into a predetermined wiring pattern by etching. The conductive pattern 24 includes a plurality of terminal portions 26 provided for the connector terminals 52 of the connector 50 to make conductive contact. Each terminal portion 26 has a long rectangle in the front-to-back direction (the insertion / removal direction relative to the edge portion 12) in a plan view and is arranged with predetermined intervals between them.

[0039] Each terminal portion 26 extends to the vicinity of the substrate edge 23 at the edge portion 12. On the electrical insulating layer 22, there is a gap G1 in the front-to-back direction (see Figure 2) between the terminal portion 26A on the substrate edge 23 side of the terminal portion 26 and the substrate edge 23. The distance between the terminal portion 26A of each terminal portion 26 and the substrate edge 23 (gap G1) can be changed within a range that appropriately ensures insulation between the conductive pattern 24 and the metallic base layer 20 and ensures conductive contact between each terminal portion 26 and the connector terminal 52.

[0040] A metallic wear-resistant layer 28 is provided on the electrical insulating layer 22 between the end portion 26A of each terminal portion 26 and the substrate edge 23. Each wear-resistant layer 28 is positioned at a distance G2 from the end portion 26A of the corresponding terminal portion 26 and forms a rectangle extending in the front-rear direction from the edge 28A on the end portion 26A side of the terminal portion 26 to the substrate edge 23. As a result, the edge 28B of the wear-resistant layer 28 on the substrate edge 23 side and the substrate edge 23 are substantially flush.

[0041] The gap G2 exists between the edge 28A of the wear-resistant layer 28 and the terminal portion 26A of the terminal portion 26, and sets an insulating gap to electrically isolate the terminal portion 26 from the wear-resistant layer 28. The gap G2 is determined according to the voltage withstand specification and is preferably about 0.2 to 0.5 mm. The wear-resistant layer 28 is also electrically isolated from the base layer 20 which is connected to earth.

[0042] The wear-resistant layer 28 is made of the same conductive material as the conductive pattern 24. The wear-resistant layer 28 is formed together with the conductive pattern 24 by etching copper foil or the like laminated on the base layer 20. This eliminates the need for a separate process to provide the wear-resistant layer 28. Furthermore, the wear-resistant layer 28 has approximately the same thickness as the conductive pattern 24. As a result, the upper surface of the terminal portion 26 and the upper surface of the wear-resistant layer 28 are flush, allowing the connector terminal 52 to slide smoothly from the wear-resistant layer 28 to the terminal portion 26.

[0043] The wiring board 10 further has an electrically insulating protective layer 30. The protective layer 30 continuously covers the wear-resistant layer 28, the portion of the electrically insulating layer 22 exposed to the outside at the interval G2, and the portion near the end portion 26A of each terminal portion 26. The protective layer 30 is made of a resin solder resist or the like. As shown in Figure 2, the protective layer 30 is provided in common for multiple terminal portions 26 and forms a strip that extends in the direction of arrangement (left-right direction) of the terminal portions 26. Preferably, the protective layer 30 is made of a material that is harder than the electrically insulating layer 22 and has better wear resistance and cut resistance than the electrically insulating layer 22.

[0044] Due to the layering (coating) process, the protective layer 30 tends to become thinner in the areas corresponding to the terminal portion 26 and the edge corner portion C of the wear-resistant layer 28, as shown in Figure 3. The protective layer 30 only needs to have a layer thickness of about 5 μm or more in the area where the layer thickness is thinnest, starting from the edge corner portion C.

[0045] The protective layer 30 covers the terminal portion 26A of the terminal portion 26 and includes a portion that overlaps with the terminal portion 26A of the terminal portion 26, thereby ensuring that the electrical insulation layer 22 is not exposed to the outside in the gap G2. In other words, the gap G2 between each wear-resistant layer 28 and the corresponding terminal portion 26A of the terminal portion 26 is reliably filled by the protective layer 30. Furthermore, the protective layer 30 includes a portion that overlaps with the terminal portion 26, which suppresses the peeling of the terminal portion 26A of the terminal portion 26 from the electrical insulation layer 22. If the protective layer 30 covered the entire terminal portion 26, it would hinder the electrical connection between the terminal portion 26 and the connector terminal 52, so the protective layer 30 covers only the portion near the terminal portion 26A of the terminal portion 26.

[0046] The wear-resistant layer 28 and the protective layer 30 prevent the connector terminals 52 from sliding against the electrical insulation layer 22 when inserting or removing the connector 50 from the wiring board 10.

[0047] This prevents the electrical insulating layer 22 between the termination portion 26A of each terminal portion 26 and the edge 23 of the substrate from being scraped by the sliding contact of the connector terminal 52. As a result, insulation failures caused by scraping of the electrical insulating layer 22 and conductivity failures caused by scraping debris of the electrical insulating layer 22 are suppressed.

[0048] The wear-resistant layer 28 mechanically protects the electrical insulation layer 22 to prevent it from suffering mechanical damage such as abrasion. The protective layer 30, together with the wear-resistant layer 28, mechanically provides double protection to the electrical insulation layer 22. In particular, the protective layer 30 prevents the portion of the electrical insulation layer 22 exposed to the outside at the gap G2 from suffering mechanical damage due to sliding contact with the connector terminal 52.

[0049] The protective layer 30 also functions as an electrical protective layer to prevent electrical short circuits from occurring between the wear-resistant layer 28 and other parts such as the base layer 20.

[0050] (Embodiment 2) Embodiment 2 of a card edge type printed circuit board will be described with reference to Figures 4 and 5. In Figures 4 and 5, parts corresponding to Figures 2 and 3 are given the same reference numerals as those used in Figures 2 and 3, and their descriptions are omitted.

[0051] In Embodiment 2, each wear-resistant layer 28 extending between the end portion 26A of each terminal portion 26 and the substrate edge 23 terminates at a distance G3 in the front-rear direction relative to the substrate edge 23. The protective layer 30 includes a portion that covers the wear-resistant layer 28 and the portion of the electrical insulation layer 22 exposed to the outside at the distance G2, a portion that covers the portion near the end portion 26A of the terminal portion 26, and a portion that covers the end edge 28B (end face) of the wear-resistant layer 28 on the substrate edge 23 side.

[0052] In Embodiment 2, the presence of a gap G3 and the fact that the protective layer 30 includes a portion that covers the edge 28B of the wear-resistant layer 28 on the substrate edge 23 side makes the electrical disconnection of the wear-resistant layer 28 from the base layer 20 even more reliable.

[0053] (Embodiment 3) Embodiment 3 of a card edge type printed circuit board will be described with reference to Figure 6. In Figure 6, parts corresponding to those in Figure 2 are given the same reference numerals as those in Figure 2, and their descriptions are omitted.

[0054] In Embodiment 3, the protective layer 30 is omitted. In Embodiment 3, an abrasion-resistant layer 28 equivalent to that of Embodiment 1 is provided, so that the electrical insulation layer 22 between the termination portion 26A of each terminal portion 26 and the substrate edge 23 is not scraped away by the sliding contact of the connector terminal 52. As a result, in Embodiment 3 as well, the occurrence of insulation failure caused by scraping of the electrical insulation layer 22 and conductivity failure caused by scraping debris of the electrical insulation layer 22 is suppressed.

[0055] (Embodiment 4) Embodiment 4 of a card edge type printed circuit board will be described with reference to Figures 7 and 8. In Figures 7 and 8, parts corresponding to Figures 2 and 3 are given the same reference numerals as those used in Figures 2 and 3, and their descriptions are omitted.

[0056] In Embodiment 3, the wear-resistant layer 28 is omitted. In Embodiment 4, a protective layer 30 equivalent to the protective layer 30 in Embodiment 1 is provided. The protective layer 30 extends continuously from the substrate edge 23 to the portion covering the vicinity of the terminal portion 26A of the terminal portion 26.

[0057] The protective layer 30 prevents the electrical insulation layer 22 between the termination portion 26A of each terminal portion 26 and the substrate edge 23 from being scraped by the sliding contact of the connector terminal 52. As a result, in Embodiment 3 as well, the occurrence of insulation failure caused by scraping of the electrical insulation layer 22 and conductivity failure caused by scraping debris of the electrical insulation layer 22 are suppressed.

[0058] (Embodiment 5) Embodiment 5 of a card edge type printed circuit board will be described with reference to Figure 9. In Figure 9, parts corresponding to those in Figure 3 are given the same reference numerals as those in Figure 3, and their descriptions are omitted.

[0059] In Embodiment 5, the protective layer 30 includes an extension 32 that continuously covers the end face 28B of the wear-resistant layer 28 on the substrate edge 23 side, the end face 22A of the electrical insulation layer 22 on the substrate edge 23 side, and the end face 20A of the base layer 20 on the substrate edge 23 side.

[0060] In Embodiment 5, the extension 32 improves the electrical insulation between the base layer 20 and the wear-resistant layer 28. This makes it even more reliable to prevent the wear-resistant layer 28 from becoming electrically conductive with the base layer 20.

[0061] (Embodiment 6) Embodiment 6 of a card edge type printed circuit board will be described with reference to Figure 10. In Figure 10, parts corresponding to those in Figure 2 are given the same reference numerals as those in Figure 2, and their descriptions are omitted.

[0062] In Embodiment 6, the wear-resistant layer 28 forms a strip-shaped portion that extends in the direction of arrangement (left-right direction) of the multiple terminal portions 26 and is provided in common to all of the multiple terminal portions 26.

[0063] In Embodiment 6, the electrical insulating layer 22 between the terminal portion 26A of each terminal portion 26 and the substrate edge 23 is prevented from being scraped by the sliding contact of the connector terminal 52. As a result, in Embodiment 6 as well, the occurrence of insulation failure due to scraping of the electrical insulating layer 22 and conductivity failure due to scraping debris of the electrical insulating layer 22 is suppressed. Since the wear-resistant layer 28 is not individually provided for each of the multiple terminal portions 26, the wear-resistant layer 28 is less likely to peel off from the electrical insulating layer 22 compared to the case where it is individually provided for each terminal portion 26.

[0064] Although the present invention has been described above in terms of preferred embodiments, as will be easily understood by those skilled in the art, the present invention is not limited to these embodiments and can be modified as appropriate without departing from the spirit of the invention. The wiring board 10 may be a double-sided wiring board having an electrical insulating layer 22 and a conductive pattern 24 on both the front and back surfaces of the base layer 20. [Explanation of symbols]

[0065] 10: Card edge type printed circuit board (wiring board) 12: Edge part 20: Base layer 20A: Edge 22: Electrical insulating layer 22A:Edge 23: Edge of circuit board 24: Conductive pattern 26:Terminal section 26A:Terminal part 28: Wear-resistant layer 28A:Edge 28B:Edge 30:Protective layer 32 :Extension part 50: Card edge connector (connector) 52: Connector terminals

Claims

1. A card edge type printed wiring board having a metal base layer, an electrical insulating layer laminated on one side of the base layer, and a conductive pattern formed on the electrical insulating layer, wherein the conductive pattern includes terminal portions provided so as to extend to the vicinity of the edge of the base layer for the connector terminals to make conductive contact, A wear-resistant metal layer is provided on the electrical insulating layer between the terminal end portion on the edge side of the terminal portion and the edge of the base layer, with a gap between it and the terminal end portion of the terminal portion. It has an electrically insulating protective layer, The protective layer has a portion that covers the wear-resistant layer and a portion that covers the electrical insulation layer between the wear-resistant layer and the terminal portion of the terminal, continuously. The protective layer is a card-edge type printed circuit board having higher hardness than the electrical insulating layer.

2. The card edge type printed circuit board according to claim 1, wherein the protective layer includes a portion that covers the portion near the terminal end of the terminal portion.

3. The card edge type printed wiring board according to claim 1 or 2, wherein the protective layer includes a portion that covers the end face of the wear-resistant layer on the edge side of the base layer.

4. The card edge type printed circuit board according to any one of claims 1 to 3, wherein the wear-resistant layer extends to the edge.

5. The card edge type printed wiring board according to any one of claims 1 to 4, wherein the wear-resistant layer terminates at a distance from the edge of the base layer.

6. The card edge type printed circuit board according to any one of claims 1 to 5, wherein the wear-resistant layer is made of the same conductive material as the terminal portion and has substantially the same thickness.

7. The card edge type printed wiring board according to any one of claims 1 to 6, wherein the terminal portion includes a plurality of terminal portions arranged in the left-right direction, and the wear-resistant layer is provided in common with the plurality of terminal portions and forms a strip-shaped portion extending in the left-right direction.

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