Circuit Board

Abstract

To provide a circuit board that has a protective film, is such a type that a mating contact slides on the protective film to be mounted on a pad, and suppresses deterioration due to attachment and detachment.SOLUTION: A circuit board includes: a plate-like substrate 40; a pad 20 that is formed on a surface of the substrate 40 and performs electrical contact with a mating contact; and a protective film 30 that extends on the surface of the substrate 40 in contact with an edge of the pad 20. Further, the edge of the pad 20 and a portion of the protective film 30 in contact with the edge of the pad 20 have a height that is continuous with each other. Then, the pad 20 causes the mating contact which has slid in a sliding direction in contact with the protective film 30 to mount on the pad 20 to come into contact with the mounted mating contact.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a circuit board suitable for use in a card edge connector. [Background technology]

[0002] There is known a card edge connector that uses conductive pads formed on a circuit board as contacts that make electrical contact with mating contacts provided on a mating connector. For example, Patent Document 1 discloses a card edge connector in which a protective pad is formed on the front end side of the conductive pad that makes contact with the mating contact, where the mating contact slides in during mating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3894774 Summary of the Invention [Problem to be solved by the invention]

[0004] A protective film called resist is often formed on the circuit board. Pads that provide electrical conduction are often formed on the circuit board. For example, in the case of a card edge connector, pads that provide electrical contact with the mating contacts of the mating connector are formed. When forming a protective film on the circuit board on which the pads are formed, the pads are masked widely so that the pads are not covered with the protective film, and then the resist liquid is applied. Therefore, a gap is formed between the edge of the pad and the protective film. In the case of a card edge connector, when mating with the mating connector, the mating contact slides on the protective film of the circuit board and sits on the pad, and the pad and the mating contact come into contact. Therefore, when attaching to or detaching from the mating connector, the presence of the above-mentioned gap means that the mating contact does not slide smoothly from the protective film onto the pad, or from the pad onto the protective film, and the mating contact and the circuit board may damage each other. In other words, repeated attachment and detachment may accelerate the deterioration of the mating contact and the circuit board.

[0005] In the case of the card edge connector disclosed in the above-mentioned Patent Document 1, a protective pad is shown, but a protective film covering the base of the circuit board is not shown.

[0006] An object of the present invention is to provide a circuit board having a protective film in which a mating contact slides over the protective film and rests on a pad, and which is less susceptible to deterioration due to attachment and detachment. [Means for solving the problem]

[0007] The circuit board of the present invention that achieves the above object comprises: A plate-shaped substrate; A pad formed on the surface of the base for electrical contact with a mating contact; and a protective film extending over the surface of the substrate in contact with the edge of the pad.

[0008] Since the circuit board of the present invention has a protective film that extends in contact with the edges of the pads, deterioration due to attachment and detachment is suppressed compared to a type of circuit board in which a gap is formed between the protective film and the edges of the pads.

[0009] In the circuit board of the present invention, it is preferable that the edge of the pad and the portion of the protective film in contact with the edge of the pad have a continuous height.

[0010] By having a continuous height, deterioration due to attachment and detachment is further suppressed.

[0011] In the circuit board of the present invention, the pad makes the mating contact, which is in contact with the protective film and slides backward in a predetermined sliding direction, ride up onto the pad, and makes contact with the mating contact that has run up onto the pad, It is preferable that the edge of the pad at the front end in the sliding direction extends linearly in the width direction intersecting with the sliding direction.

[0012] If the front edge of the pad in the sliding direction is sharp, the mating contact is likely to be damaged when it rides up onto the pad because it comes into contact with the sharp, narrow front edge. In contrast, if the front edge of the pad extends linearly in the width direction that intersects with the sliding direction, damage is reduced compared to pads with a front edge that is sharp.

[0013] In addition, in the circuit board of the present invention, The pads are arranged in a plurality of sequentially spaced rows in the sliding direction, It is preferable that the protective film extends over the surface of the base body, contacting both the rear edge of a first pad that is positioned relatively forward among the multiple pads arranged in the sliding direction, and the front edge of a second pad that is adjacent to and rear of the first pad.

[0014] With this structure, damage is suppressed during both insertion and removal, from the time when the mating contact rides up onto the first pad or the second pad to the time when it rides up onto the other pad.

[0015] In addition, in the circuit board of the present invention, A plurality of rows of pads are arranged at intervals in the sliding direction, and the rows are arranged in a width direction intersecting the sliding direction; It is preferable that the pads arranged in two rows adjacent in the width direction are formed at positions offset from each other in the sliding direction.

[0016] By forming the pads at positions offset from one another in the sliding direction, the pads can be arranged more densely in the width direction than if the pads were formed at the same positions in the sliding direction, which contributes to the miniaturization of the circuit board.

[0017] In a preferred embodiment of the circuit board of the present invention, the pads and the protective film are formed on both sides of the substrate.

[0018] By forming it on both sides of the base, the circuit board can be made smaller.

[0019] Furthermore, in the circuit board of the present invention, a front end portion of the base body on a side where the mating contact moves rearward in the sliding direction and first comes into contact with the protective film has a tapered shape whose thickness decreases toward the front; A protective membrane preferably extends over the front end.

[0020] By having a tapered front end and covering the front end with a protective film, mating with a mating connector is facilitated and damage to the front end or the mating contact is suppressed.

[0021] Furthermore, in the circuit board of the present invention, it is preferable that the protective film has a lower coefficient of friction than the surface of the substrate. By forming a protective film with a low coefficient of friction, insertion and removal can be performed smoothly. Effect of the Invention

[0022] According to the circuit board of the present invention, deterioration due to attachment and detachment (damage to the mating contact or the circuit board) can be suppressed. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view of a circuit board according to an embodiment of the present invention; [Diagram 2] 2A is a top view, FIG. 2B is a side view, and FIG. 2C is a bottom view of the circuit board shown in FIG. 1 in a perspective view. [Diagram 3] 2(A) is an enlarged view (R1) of a portion of the surface of the circuit board indicated by a circle R1 shown by a dashed line in FIG. 2(A), and FIG. 2(R2) is an enlarged cross-sectional view of a portion of the circuit board indicated by a circle R2 shown by a dashed line in FIG. 2(B). [Figure 4] FIG. 13 is a diagram showing the measurement results of the height distribution on the surface of a circuit board. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described.

[0025] FIG. 1 is a perspective view of a circuit board according to an embodiment of the present invention.

[0026] 2A is a top view, FIG. 2B is a side view, and FIG. 2C is a bottom view of the circuit board shown in FIG.

[0027] 1 and 2, elements on the circuit board other than those characteristic of this embodiment are omitted from the illustration, and the explanation of the elements that are omitted from the illustration will also be omitted.

[0028] A large number of pads 20 are arranged on both the front surface (see FIG. 2(A)) and the back surface (see FIG. 2(B)) of this circuit board 10. By forming the pads 20 on both the front and back surfaces of the circuit board 10 in this way, it is possible to arrange a larger number of pads 20 than in the case where the pads 20 are formed on only one surface, and also to make the circuit board 10 smaller in size for the same number of pads 20.

[0029] 1 and 2 are pads that are responsible for electrical contact with mating contacts provided in a mating connector (not shown). That is, the portion of the circuit board 10 where the pads 20 are arranged is used as a card edge connector 10A. At least the portion of the circuit board 10 that is the card edge connector 10A is entirely covered with a protective film called a resist, except for the area directly above the pads 20.

[0030] This card edge connector 10A is mated with the mating connector by being inserted into the mating connector in the direction indicated by arrow F. This mating connector is provided with mating contacts in the same arrangement as the pads 20 of the circuit board 10, and in the same number as the pads 20. When this card edge connector 10A is completely mated with the mating connector, each of the arranged pads 20 is in contact with one of the mating contacts.

[0031] Here, the arrangement of the pads 20 on the circuit board 10 will be described.

[0032] The pads 20 are arranged in multiple rows (13 rows in this example) in the width direction indicated by the arrow W. In each row, multiple pads 20 (8 pads in this example) are arranged at intervals in the direction of the arrow FR.

[0033] When mating with the mating connector, the card edge connector 10A is inserted into the mating connector in the direction of the arrow F. At this time, for example, the mating contact that comes into contact with the pad 20_8 arranged at the rearmost position when fully mated repeats contact with the pad 20 as follows as the mating proceeds. That is, the mating contact that comes into contact with the pad 20_8 slides on the protective film 30 toward the rear as indicated by the arrow R, and first passes over the frontmost pad 20_1 while coming into contact with the pad 20_1. Then, it leaves the pad 20_1 and slides again on the protective film 30. Next, it passes over the pad 20_2 while coming into contact with the second pad 20_2 from the front. This is repeated, and finally it comes into contact with the pad 20_8 arranged at the rearmost position. Also, for example, the mating contact that contacts the second pad 20_2 from the front when fully mated slides on the protective film 30 later than the mating contact that contacts any of the third and subsequent pads 20_3, . . . , 20_8 from the front, and passes over the frontmost pad 20_1 while contacting the pad. Thereafter, it leaves the pad 20_1 and slides on the protective film 30 again. Then, when fully mated, it contacts the second pad 20_2 from the front. In this way, the mating contact corresponding to the pad 20_n arranged at the rear as indicated by the arrow R contacts the pads 20_1 to 20_n-1 arranged in front of the pad 20_n in sequence, and then contacts the corresponding pad 20_n. When the card edge connector 10A is removed from the mating connector, the trajectory is reverse to that when mated. That is, the mating contact corresponding to the pad 20_n arranged at the rear as indicated by the arrow R is extracted while successively coming into contact with the pads 20_n-1 to 20_1 arranged in front of the pad 20_n.

[0034] In addition, when a plurality of pads 20 (eight in the example shown here) arranged in the direction of the arrow FR are considered as one row, a plurality of rows (thirteen rows in the example shown here) are arranged in the width direction indicated by the arrow W. The pads 20 belonging to each of two rows adjacent in the width direction are arranged in positions offset from each other in the sliding direction indicated by the arrow FR. By forming the pads 20 in such offset positions, the area where no pads 20 are present becomes wider around each pad 20 compared to the case where the pads 20 are formed in the same position in the sliding direction. When the area where no pads 20 are present becomes wider, the pads 20 are less susceptible to electrical influence from adjacent pads 20, and as a result, the pads 20 can be arranged densely in the width direction. This realizes a miniaturized circuit board.

[0035] Fig. 3 is an enlarged view (R1) of the portion of the surface of the circuit board indicated by a broken line in circle R1 in Fig. 2(A), and an enlarged cross-sectional view (R2) of the portion of the circuit board indicated by a broken line in circle R2 in Fig. 2(B). Here, Fig. 2(B) is a side view of the circuit board, while Fig. 3(R2) is a cross-sectional view of the corresponding portion.

[0036] 3(R1), the pad 20 in this embodiment has a substantially rectangular shape. The front edge 20a of each pad 20 in the sliding direction indicated by the arrow F extends linearly in the width direction indicated by the arrow W.

[0037] If the edge of the front end of the pad in the sliding direction is sharpened forward, the sliding mating contact comes into contact with the sharp, narrow front end as it rides up onto the pad 20, and the mating contact is likely to be damaged. In contrast, in this embodiment, if the edge of the front end of the pad 20 extends linearly in the width direction intersecting with the sliding direction, damage is suppressed compared to a pad with a shape in which the edge of the front end is sharpened forward.

[0038] The protective film 30 contacts the edge of each pad 20 all around without forming a gap between the pad and the edge, and spreads over the surface (both the front and rear surfaces) of the plate-like base 40. Here, as a specific example, attention is given to two pads 20 adjacent to each other in the sliding direction indicated by the arrow F, for example, the first pad 20_1 and the second pad 20_2 shown in FIG. 3. The protective film 30 contacts the edge of each pad 20 all around and spreads over the base 40. Therefore, the protective film 30 contacts both the rear edge 20b of the first pad 20_1 and the front edge 20a of the second pad 20_2, and spreads over the base 40. In this structure, damage to the mating contact caused by insertion and removal during the period from when the mating contact runs over one pad 20 (the first pad 20_1 or the second pad 20_2) to when the mating contact runs over the other pad 20 is suppressed. In the present embodiment, this structure is continuous with the eight pads 20 aligned in the sliding direction and the protective film 30 filling the spaces between them as shown in Fig. 1 or 2. Therefore, in the present embodiment, damage to the mating contacts caused by insertion and removal from the mating connector is suppressed.

[0039] To form the protective film 30 that contacts the edges of each pad 20 without forming any gaps, for example, the following process is adopted. That is, a protective film material is applied to cover the entire surface of the base 40 on which the pads 20 are formed, or the edges of the pads 20. Then, a buff finish is performed to make the surface flat. In this way, the protective film 30 that contacts the edges of each pad 20 without forming any gaps can be formed.

[0040] In the present embodiment, the base 40 has a front end 10B on the side where the mating contact of the base 40 moves rearward in the sliding direction (in the direction of arrow R) and first comes into contact with the protective film 30, which has a tapered shape that decreases in thickness toward the front (in the direction of arrow F). The protective film 30 spreads and covers the front end 10B.

[0041] In this manner, front end 10B of base 40 has a tapered shape, and front end 10B is covered with protective film 30, thereby facilitating mating with a mating connector and reducing damage to the mating contact and the circuit board.

[0042] Furthermore, in this embodiment, the protective film 30 has a lower coefficient of friction than the surface of the base body 40. By forming the protective film 30 with a low coefficient of friction, insertion and removal can be performed smoothly.

[0043] The material for forming the protective film 30 may be a resist that is generally used to protect the surface of a circuit board, a resin with a low coefficient of friction, a glass-based coating agent, or the like.

[0044] 4 is a diagram showing the measurement results of the height distribution on the surface of a circuit board, where (A) is a comparative example to be compared with the present invention, and (B) is an example showing an example of the present invention.

[0045] In the comparative example of FIG. 4(A), as shown in (P) of (A) in the upper left of FIG. 4, a groove 50 is present between the pad 20 and the protective film 30 on the circuit board 10, exposing the base 40 (see FIG. 3(R2)). When covering the base 40 with the protective film 30, conventionally, as shown in FIG. 4(A), in order to expose the entire area of ​​the pad 20 from the protective film 30, the pad 20 is covered with a mask larger than the pad 20 and the material of the protective film 30 is applied. For this reason, the protective film 30 is formed slightly away from the edge of the pad 20, and a groove 50 is formed between the pad 20 and the protective film 30. The shape of the pad 20 is tapered in the sliding direction.

[0046] In contrast, in the embodiment shown in FIG. 4, as shown in (P) of (B) at the bottom left of FIG. 4, the protective film 30 on the circuit board 10 contacts the edge of the pad 20, and there is no groove between them. As described above, this structure is achieved by, for example, covering the pad 20 with a mask smaller than the pad 20 and applying the material of the protective film 30. Therefore, the protective film 30 is formed so as to overlap the edge of the pad 20 at one time. Then, the surface is buffed to be flat. As a result, the portion of the protective film 30 that overlaps the edge of the pad 20 is scraped off, exposing the pad 20 up to its edge, and the protective film 30 that spreads in contact with the edge is formed. In addition, in this embodiment, the pad 20 has a substantially rectangular shape, and an edge extending in the width direction is formed.

[0047] FIG. 4(X) is a diagram showing the height distribution of the surface of the circuit board 10 along the horizontally extending dashed line X for each of FIGS. 4(A) and 4(B).

[0048] FIG. 4(Y) is a diagram showing the height distribution of the surface of the circuit board 10 along the vertically extending dashed line Y for each of FIGS. 4(A) and 4(B).

[0049] As can be seen from these figures, in the comparative example (A), a deep groove 50 is formed. Therefore, when the sliding mating connector passes through this groove 50, it damages the circuit board 10, and if this is repeated, there is a risk of problems such as the surface of the circuit board 10 being scraped or the edge of the pad 20 being turned up (which in turn includes problems such as damage and wear to the sliding mating contact). On the other hand, in the example (B), the groove 50 is not formed, and the edge of the pad 20 and the part of the protective film 30 that contacts the edge of the pad 20 are at the same height. Therefore, even if the mating contact moves across the pad 20 and the protective film 30, the damage to the mating contact or the damage to the circuit board 10 is extremely small. Therefore, in this example, a highly reliable circuit board in which the risk of the above-mentioned problems occurring is suppressed is realized.

[0050] In the above description, a card edge connector 10A in which multiple pads 20 are arranged two-dimensionally as shown in Figures 1 and 2 has been taken up for explanation. However, the present invention can also be applied to a card edge connector in which the pads 20 are arranged in only one row in the width direction.

[0051] Furthermore, the application of the present invention is not limited to card edge connectors, but can also be applied to, for example, a type of circuit board in which two-dimensionally arranged mating contacts approach the circuit board from above and, with some sliding, are pressed against two-dimensionally arranged pads on the circuit board. [Explanation of symbols]

[0052] 10 Circuit Board 10A Card Edge Connector 10B Front end 20,20_1,··,20_8 Pad 20a Front edge of pad 20b Rear edge of pad 30 Protective film 40 Substrate 50 grooves

Claims

1. A plate-shaped substrate; A plurality of pads arranged in a matrix are formed on the surface of the base and serve to make electrical contact with mating contacts; a protective film that contacts the edge of the pad, spreads over the surface of the substrate, and has a low coefficient of friction compared to the surface of the substrate; The pads arranged in a first direction are arranged such that a portion of each of the pads overlaps with another portion of the pads in the first direction. Two of the pads adjacent to each other in the first direction are biased from each other in a second direction perpendicular to the first direction, The rows of the pads arranged in the first direction are arranged in a plurality of rows at intervals in the second direction, A circuit board, characterized in that the pads belonging to the row of pads arranged in the first direction do not overlap with the pads belonging to a row adjacent to the row in the first direction.

2. 2. The circuit board according to claim 1, wherein an edge of the pad and a portion of the protective film in contact with the edge have a height that is continuous with each other.

3. The first direction is a width direction, and the second direction is a sliding direction, The pad makes the mating contact, which is in contact with the protective film and slides backward in the predetermined sliding direction, ride up onto the pad and come into contact with the mating contact, 3. The circuit board according to claim 1, wherein an edge of a front end of the pad in the sliding direction extends linearly in the width direction intersecting with the sliding direction.

4. The pads are arranged in a plurality of rows at intervals in the sliding direction, 4. The circuit board according to claim 3, wherein the protective film extends over the surface of the base, contacting both the rear edge of a first pad that is disposed relatively forward among the pads arranged in the sliding direction, and the front edge of a second pad that is adjacent to and rear of the first pad.

5. 5. The circuit board according to claim 3, wherein the pads and the protective film are formed on both sides of the base.

6. a front end portion of the base body on a side where the mating contact moves rearward in the sliding direction and first comes into contact with the protective film has a tapered shape whose thickness decreases toward the front, 6. A circuit board as claimed in any one of claims 3 to 5, characterised in that the protective membrane extends over the front end.

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