JP4300348B2 - Press-fit pin mounting board structure and press-fit pin connection inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a press-fit pin mounting substrate structure and a press-fit pin connection inspection method in which a press-fit pin is press-fitted into a through hole provided in a substrate for mounting.
[0002]
[Prior art]
Press-fit pins that serve as electrodes are press-fitted into through-holes that have copper plating or other conductors formed on the printed wiring board on the inner wall, and are mechanically held by electrical connection and contact pressure between the press-fit pins and the inner wall of the through-hole. There is known a press-fit method for ensuring the above.
[0003]
In such a press-fit method, the electrical continuity test between the press-fit pin and the through-hole is conventionally performed by using a through-hole land or a test pad or by confirming the operation by electrical continuity from the press-fit pin. ing.
[0004]
In particular, the electrical connection between the press-fit pin and the inner wall of the through hole is ensured by mechanical holding between the two, so that the outer diameter of the press-fit pin and the through-hole It is necessary to design the hole diameter with high accuracy, and various devices have been devised for the shape of the press-fit pin.
[0005]
FIG. 4 shows a state in which the press-fit pin 5 is press-fitted in the direction indicated by the arrow A into the through hole 3 provided in the substrate 1. A through-hole copper plating 7 is formed on the inner wall of the through-hole 3, and a through-hole copper plating land 9 continuous with the through-hole copper plating 7 is formed on the substrate surface around the opening of the through-hole 3. .
[0006]
Here, as shown in FIG. 4A, when a positional deviation occurs between the center line X of the press-fit pin 5 and the center line Y of the through hole 3, the tip of the press-fit pin 5 is While being in contact with the through-hole copper plating land 9, it is strongly pressed in the press-fitting direction. For this reason, as shown in FIG.4 (b), the press fit pin 5 may generate | occur | produce the copper plating scraping part 13, pushing the scraped copper plating piece 11 out.
[0007]
Further, as shown in FIG. 5A, when the copper plating scraped portion 13 reaches the connecting portion between the through-hole copper plating 7 and the inner layer wiring 15, the connecting portion is disconnected and the disconnecting portion 17 is disconnected. Occurs, and the inner-layer wiring 15 and the press-fit pin 5 cannot be electrically connected.
[0008]
The above-mentioned misalignment between press-fit pins and through-holes is also a recent trend, and various lead-shaped parts are made into press-fit pins and collectively printed on a printed wiring board due to the demand for cost reduction in in-vehicle electronic devices. This is likely to occur in the press-fitting assembly method.
[0009]
That is, as shown in FIG. 6, the press-fit parts 23, 25, 27, and 29 having press-fit pins are used to form errors of the individual press-fit parts 23, 25, 27, and 29 and the parts holder, and to the parts holder. Mounting accuracy of each press fit part 23, 25, 27, 29, hole position accuracy of the through hole 33 formed in the printed wiring board 31, positioning accuracy of the printed wiring board 31 to the part holder case 35, and press fit pin The frequency of occurrence of misalignment between the press-fit pin and the through hole is increased due to the falling of the pin.
[0010]
Also, in order to obtain a high holding force between the press-fit pin and the through-hole, if the hole diameter of the through-hole is made smaller than the outer diameter of the press-fit pin and the two are designed to fit tightly, the force during press-fitting will also increase. Become. For this reason, as shown in FIG. 5 (b), which is a BB cross-sectional view of FIG. 5 (a) described above, the deformed portion 19 of the through hole 3 is generated, the copper plating scraped portion 21 is easily generated, and the press The occurrence of buckling of the fit pin 5 is also a concern.
[0011]
Therefore, there is a need for reliable detection of through-hole plating scraping and buckling of press-fit pins that are likely to occur due to the above-described misalignment.
[0012]
For example, the buckling of the press-fit pin can be detected simply by visual inspection from the outlet side of the press-fit pin or by detecting an abnormal insertion pressure or abnormal insertion depth of the press-fitting machine. Furthermore, as shown in the following Patent Document 1, there is a method in which an electrode pattern capable of detecting a short circuit with a press-fit pin is provided on a substrate when buckling of the press-fit pin occurs, and an electrical continuity test is performed.
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-237664
[Problems to be solved by the invention]
However, the detection of through-hole plating scraping is performed by visual inspection. When plating scraping occurs inside a through-hole into which a press-fit pin has been press-fitted, visual inspection from the outside observes the degree of breakage. There is a problem that you can not.
[0015]
Accordingly, an object of the present invention is to reliably detect the breakage of the conductive layer provided on the inner wall of the through hole.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a press-fit pin mounting board structure in which a press-fit pin is press-fitted into a through-hole provided in a board, and a conduction check pattern is provided on the surface of the board. An inner layer wiring for inspection connected to the pattern for continuity check is provided inside the substrate, and the inner layer wiring for inspection and the conductive layer provided on the inner wall of the through hole are narrower than the inner layer wiring for inspection. A conductive portion for checking, which is connected at the connecting portion and connected to the conductive layer on the inner wall of the through hole, is provided on the surface of the substrate.
[0017]
【The invention's effect】
In the through hole before press-fitting the press-fit pin, the conductive layer on the inner wall of the through hole and the conductive check pattern on the substrate surface are kept connected by the inner wiring for inspection and the connecting portion. When a press-fit pin is press-fitted into this through-hole, if excessive press-fitting stress acts on the through-hole, the conductive layer and connection part on the inner wall of the through-hole are scraped, and the connection part that connects the inner wiring for inspection and the conductive layer Is disconnected. This disconnection of the connection part can be confirmed by detecting the electrical connection state between the conduction check pattern on the substrate surface and the check conduction part on the substrate surface connected to the conduction layer of the through hole. It is possible to reliably detect the breakage of the conductive layer provided on the inner wall.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a cross-sectional view of a press-fit pin mounting substrate structure according to an embodiment of the present invention. A through-hole 39 is provided in the printed wiring board 37, and a through-hole copper plating 41 as a conductive layer is formed on the inner wall of the through-hole 39. A press-fit pin 43 is press-fitted and mounted in the through hole 39 from the direction indicated by the arrow C in the drawing.
[0020]
A through-hole copper plating land 45 as a conducting portion for check that is conducted to the through-hole copper plating 41 is provided on the substrate surface 37 a around the press-fit pin 43 press-fitting side of the through-hole 39 described above.
[0021]
The printed wiring board 37 is provided with an inspection through hole 47 having a diameter smaller than that of the through hole 39, and an inspection through hole copper plating 49 as an inspection through hole conductive layer is formed on the inner wall of the inspection through hole 47. Form. On the surface 37 a of the printed wiring board 37 around the opening of the inspection through hole 47, a conduction check test pad 51 is provided as a conduction check pattern that conducts to the inspection through hole copper plating 49.
[0022]
FIG. 2 is a plan view of the press-fit pin mounting substrate structure shown in FIG. 1, and a plurality of inspection through holes 47 are provided around the through hole 39.
[0023]
In the present embodiment, the test pad 51 is formed on the surface 37a of the press-fit pin 43 on the press-fit pin 43 side of the printed wiring board 37. For example, the printed wiring board is a test pad 51 'shown by a broken line in FIG. 37 press-fit pins 43 may be formed on the surface opposite to the press-fitting side.
[0024]
An inner layer wiring 53 for inspection is provided inside the substrate having a dimension H (50 μm to 300 μm) from the surface 37 a of the printed wiring board 37 described above. As shown in FIG. 3 which is a DD cross-sectional view of FIG. 1, the inspection inner layer wiring 53 has one end connected to the inspection through hole copper plating 49 of each inspection through hole 47 and the other end connected to the through hole. It has a tapered shape that extends toward 39 and gradually decreases in width as it approaches the through hole 39.
[0025]
Then, the tapered end of the inner layer wiring 53 for inspection and the through-hole copper plating 41 of the through hole 39 are connected by a connecting portion 55 that is narrower than the inner layer wiring 53 for inspection. The connecting portion 55 does not have an annular inner layer land (such as the through-hole copper-plated land 45 on the substrate surface 37a) that surrounds the periphery of the through-hole 39, and its width L is 200 μm or less. It is small.
[0026]
As shown in FIG. 1, an inner layer wiring 54 is provided inside the substrate further below the above-described inspection inner layer wiring 53. This inner layer wiring 54 is for connecting to other through holes (not shown) in the printed wiring board 37 and corresponds to the inner layer wiring 15 provided in FIG.
[0027]
Next, the operation will be described. After the press-fit pins 43 are press-fitted into the through holes 39 and mounted as shown in FIG. 1, a pair of electrode terminals 61 and 63 for continuity inspection are provided on the through-hole copper plating land 45 and the continuity confirmation test pad 51. Each is brought into contact with each other, and an electrical conduction state between them is detected.
[0028]
Here, if electrical continuity is established between the pair of electrode terminals 61 and 63, there is no disconnection of the connecting portion 55 as shown by a P portion in FIG. It will not occur.
[0029]
On the other hand, when electrical continuity is not established between the pair of electrode terminals 61, 63, the through-hole copper plating 41 near the entrance of the through-hole 39 is scraped to generate a copper plating scraped portion 57, and The connection portion 55 which is at a very shallow position of 50 μm to 300 μm from the substrate surface 37a and is also narrowed is simultaneously cut to generate a disconnection portion 59, and the scraped copper plating piece 65 is pushed out to the outside.
[0030]
FIG. 1 shows a state in which the inner layer wiring 59 is also cut and disconnected.
[0031]
As described above, when the press-fit pin 43 is press-fitted into the through hole 39, if excessive press-fitting stress acts on the through-hole 39, the connecting portion 55 narrower than the inner wiring 53 for inspection is cut and disconnected. The disconnection portion 59 can be confirmed by detecting the electrical connection state between the conduction check pattern 51 on the substrate surface 37a and the through-hole copper plating land 45, and is thereby a conduction layer provided on the inner wall of the through-hole. The breakage of the through-hole copper plating 41 can be reliably detected.
[0032]
Note that the connecting portion 55 described above may be provided corresponding to a position where the contact pressure between the press-fit pin 43 and the through-hole copper plating 41 of the through-hole 39 is highest when the press-fit pin 43 is press-fitted. For example, the deformed portion of the through hole 39 as shown by the E portion in FIG. 3 is set specifically for the portion reaching the plating scraped portion as shown by the F portion. Thereby, the breakage of the through-hole copper plating 41 can be detected more reliably.
[0033]
Since the position where such a deformed portion E occurs varies depending on the shape of the press-fit pin and the press-fitting process, the position of the connecting portion 55 is set according to these conditions.
[0034]
Further, the connecting portion 55 described above may be provided corresponding to a position where it is assumed that the press fit pin 43 is displaced in the direction in which the press fit pin 43 approaches the inner wall of the through hole 39 when the press fit pin 43 is press-fitted.
[0035]
When the press-fit pin 43 is press-fitted into the through hole 39 in such a state in which such a shift has occurred, a copper plating scraped portion 57 as shown in FIG. 1 is generated. By setting, the breakage of the through-hole copper plating 41 can be detected more reliably.
[0036]
The position of 50 μm to 300 μm from the substrate surface 37 a on which the connection portion 55 is set is a position where friction and contact pressure with the inner wall of the through hole 39 are continuously applied in the process of press-fitting the press-fit pin 43. For this reason, when the through-hole copper plating 41 is shaved and the copper plating shaving portion 57 is generated, the connection portion 55 is also shaved and disconnected, so that the detection of the breakage of the through-hole copper plating 41 can be reliably performed. .
[0037]
Thus, by providing the connection part 55 in the shallow position inside a board | substrate, even if it is a case where the grade of the copper plating scraping part 57 is small, the failure detection of the through-hole copper plating 41 can be performed reliably. As a reference, the position at which the degree of through-hole deformation is observed in IEC (International Electrotechnical Commission) is 300 μm from the substrate surface. In general, if it is 50 μm from the substrate surface, it is possible to ensure insulation from the circuit pattern on the substrate surface.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a press-fit pin mounting substrate structure according to an embodiment of the present invention.
FIG. 2 is a plan view of the press-fit pin mounting substrate structure shown in FIG.
FIG. 3 is a sectional view taken along the line DD of FIG.
FIG. 4 is an operation explanatory view showing a state in which through-hole copper plating is scraped when press-fit pins are press-fitted into the through-holes.
5A is a cross-sectional view showing a case where the inner layer wiring is disconnected when the through-hole copper plating is cut, and FIG. 5B is a cross-sectional view taken along the line BB in FIG. 5A.
FIG. 6 is a perspective view showing an assembly method for collectively press-fitting a plurality of press-fit pins into a printed wiring board.
[Explanation of symbols]
37 Printed Wiring Board 37a Board Surface 39 Through Hole 41 Through Hole Copper Plating (Conductive Layer)
43 Press-fit pin 45 Through-hole copper-plated land (conducting part for check)
47 Through hole for inspection 49 Through hole copper plating for inspection (through hole conduction layer for inspection)
51 Test pad for continuity confirmation (pattern for continuity check)
53 Inner layer wiring 55 for inspection

Claims (8)

In a press-fit pin mounting board structure in which press-fit pins are press-fitted into a through-hole provided in the board for mounting, a continuity check pattern is provided on the surface of the board, and the continuity check pattern is provided inside the board. An inspection inner layer wiring to be connected is provided, and the inspection inner layer wiring and the conduction layer provided on the inner wall of the through hole are connected by a connection portion narrower than the inner layer wiring for inspection, and the conduction of the inner wall of the through hole is achieved. A press-fit pin mounting substrate structure, wherein a check conducting portion connected to the layer is provided on the surface of the substrate. 2. The press-fit pin mounting substrate structure according to claim 1, wherein a width of the connection portion is 200 [mu] m or less. The press-fit pin mounting substrate structure according to claim 1 or 2, wherein the connecting portion is provided at a position of 50 µm to 300 µm from the surface of the substrate on the side into which the press-fit pin is press-fitted. The connection portion is provided corresponding to a position where the contact pressure between the press-fit pin and the conductive layer of the through hole is highest when the press-fit pin is press-fitted. The press-fit pin mounting substrate structure described. The connection portion is provided corresponding to a position where the press fit pin is assumed to be displaced in a direction in which the press fit pin approaches the inner wall of the through hole when the press fit pin is press-fitted. 4. The press-fit pin mounting substrate structure according to any one of 1 to 3. An inspection through hole is provided in the substrate, and the conduction check pattern and the inspection inner layer wiring are connected via an inspection through hole conduction layer provided on an inner wall of the inspection through hole. The press-fit pin mounting substrate structure according to any one of claims 1 to 5. A continuity check pattern is provided on the surface of the substrate, and an inner layer wiring for inspection connected to the continuity check pattern is provided inside the substrate, and the continuity between the inner layer wiring for inspection and the inner wall of the through hole provided in the substrate is provided. Are connected to the conductive layer on the inner wall of the through-hole, and a press-fit pin is provided in the through-hole. After press-fitting and mounting, a press-fit pin connection inspection method for detecting an electrical continuity state between the continuity check pattern and the check continuity portion. An inspection through hole is provided in the substrate, and the conduction check pattern and the inspection inner layer wiring are connected via an inspection through hole conduction layer provided on an inner wall of the inspection through hole. The press-fit pin connection inspection method according to claim 7.

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