CN1841849A - Electronic equipment having a wiring board with press-fit and hold press-fit terminals - Google Patents

Abstract

This invention relates to a press-fit joining wiring board in an electronic control device used under high temperature environment inside an automobile. In order to suppress the occurrence of damage on a press-fit joining wiring board, a peak value of stress generated on the board in the case of a press-fitting a press-fit terminal into a through-hole is reduced so that it can not exceed the design standard value of the board. In the press-fit terminal in which a body part, retaining part, introducing part and forward end part are integrally formed, a cross-sectional area of the introducing part is reduced to be smaller than that of the retaining part, so that an intensity of the elastic force of the introducing part is decreased to be lower than that of the elastic force of the retaining part. Alternatively, on the wiring board, elastic material is filled into resin for combining sheet-like base material of the board so as to relieve an intensity of stress generated on the board itself.

Description

Electronic equipment having a wiring board with press-fit and hold press-fit terminals

technical field

The present invention relates to a press-fit terminal used in an electronic device, and a press-fit-bonded wiring board for press-fitting and holding the terminal, and particularly relates to a press-fit terminal used in a high-temperature environment when the press-fit terminal is press-fitted and mounted on a vehicle such as an automobile. In the case of electrical connection in the through hole provided on the wiring board in the electronic device, the press-fit terminal that suppresses the influence of the terminal press-fitting on the wiring board and the press-fit joint wiring board.

Background technique

Conventionally, vehicles such as automobiles are equipped with an electronic control unit (ECU) for controlling various devices such as an engine installed in the vehicle. This ECU integrates various control functions for equipment into one unit, and multiple ECUs are installed in the vehicle. Each ECU has: a control circuit part that performs theoretical control calculations including a microcomputer that operates based on electronic information detected by each sensor, and an actuator that drives a controlled object based on the calculation results to externally The power circuit part of the power control. Such an in-vehicle ECU is disclosed in, for example, Japanese Unexamined Patent Publication No. 2000-323848.

In this conventional vehicle-mounted ECU, the control circuit part is formed on a control board, and the power circuit part is built in a module. During assembly of the vehicle-mounted ECU, when the control board is assembled into the ECU, connection terminals provided upright on the module incorporating the power circuit are inserted into through holes provided on the control board. Then, the terminal for connection is soldered to the conductive member formed in the through hole by plating or the like. With this method, the control board can be fixed in the resin case while the connection terminal is electrically connected to the wiring pattern formed on the control board. However, since such a structure is adopted, the assembly work is complicated.

Therefore, in the assembly work, as a method that can reliably assemble the control board and the connection terminal, reduce the number of man-hours, and realize the board connection that does not cause deterioration of the working environment, a method for connecting the board has been proposed. A solution that uses press-fit terminals in the terminal. The method of using the press-fit terminal for the connection of the substrate of the ECU is disclosed in Japanese Unexamined Patent Publication No. 10-208798, for example.

In order to easily perform this substrate connection, a plurality of through holes are provided at predetermined intervals on the control substrate incorporated into the ECU. On the inner peripheral surface of each through hole, a conductive member is plated. On the other hand, one end of the press-fit terminal is buried and erected in the housing at a predetermined interval corresponding to the through holes. For this press-fit terminal, for example, a pinhole type can be used. Therefore, the press-fit terminal can be pressed into the through-hole from above, and the substrate can be connected by press-fit bonding.

Here, in addition to the above-mentioned press-fit terminals, for example, as disclosed in Japanese Patent Publication No. 6-28174, etc., there has been proposed a press-fit terminal having a uniform amount of elastic deformation when press-fitted into a through-hole. In this press-fit terminal, the pressure continuous part is made longer than the depth of the through hole, and when the press-fit terminal is pressed into the through-hole, the highly rigid part formed on the upper part of the press-fit terminal is located outside the through-hole. superior.

On the other hand, a control board mounted on the above-mentioned electronic control device is required to have a small coefficient of thermal expansion from the viewpoint of connection reliability. In the past, ceramic substrates, ceramic-resin substrates, fiber composite substrates, etc. have been developed to meet this requirement, but there is still no substrate that satisfies both low thermal expansion coefficient and good processability. Therefore, a metal-clad laminate is formed by heating and press-molding a prepreg layer obtained by impregnating and drying a sheet-like substrate with an epoxy resin, and a metal foil placed on the surface. , are widely used as substrates.

Therefore, for example, as disclosed in Japanese Unexamined Patent Publication No. 8-309920, it is proposed to reduce the elastic modulus of the resin by adding a flexible material to the epoxy resin, and to suppress the thermal expansion of the laminated board in the plane direction. substrate. In this laminated substrate, rubber-elastic microparticles are contained in the resin to absorb and relax the stress generated in the resin due to thermal expansion, so that the metal foil will not be damaged at high temperature even in an environment with severe temperature fluctuations. Peeling due to thermal expansion of the substrate. Thereby, thermal expansion in the planar direction of the multilayer substrate is suppressed to be small.

However, when the press-fit terminal is press-fitted into the through-hole provided on the control board, fine damage may occur at the opening of the through-hole provided on the control board due to stress concentration during press-fitting of the press-fit terminal. . In general, among control substrates, substrates having a laminated structure in which a plurality of sheets impregnated with glass fibers combined vertically and horizontally are laminated and compacted and solidified are widely used. Therefore, when the press-fit terminal is pressed in, a large force acts in the direction of the substrate surface at the opening of the through hole, causing damage to the base material such as peeling of the laminated sheet to occur near the periphery of the opening of the through hole. damage.

However, in the electronic control devices installed in the engine room of automobiles, etc., under harsh working environments such as high ambient temperature and high humidity, the damaged part of the control substrate becomes easy to absorb moisture, resulting in the occurrence of cracks in the conductive material. The elution of copper ions and the deterioration of the insulation of the substrate are problems. Especially recently, in order to obtain a variety of control functions on the electronic control device, it is desired to achieve high density and even miniaturization of the control substrate, increase the electrical connection parts of the control substrate, and reduce the distance between through holes. Therefore, the deterioration of the insulating property of the substrate is accelerated, which has become a big problem.

In addition, in order to withstand the vibration, especially for a control board of an electronic control device installed in an engine room or the like that vibrates violently, it is necessary to strengthen the holding force of the press-fit terminals. However, if the press-fit margin is increased in order to increase the holding force of the press-fit terminal, the burden on the substrate during press-fit will be increased instead, resulting in damage. Conversely, in order to reduce the load, the load (load) can be suppressed by reducing the press-fit allowance, but this causes a problem that the holding force of the press-fit terminal decreases.

Contents of the invention

Therefore, an object of the present invention is to provide a press-fit terminal that can be applied to commonly used control substrates, can suppress the burden during press-fitting, maintains the size of the holding force after press-fitting, and has higher connection reliability than hitherto.

Furthermore, an object of the present invention is to provide a method for press-fitting a press-fit terminal into a through-hole provided on a wiring board in an electronic control device used in a high-temperature environment, for example, to perform electrical bonding. This is a press-fit wiring board that absorbs external stress during press-fitting of the terminals and suppresses the load generated inside the board. In addition, there is also provided a substrate structure in which a conventional press-fit terminal can be used as it is, and the substrate can absorb the stress exerted on the substrate by the terminal.

In order to solve the above problems, in the present invention, the press-fit terminal that is press-fitted and held in the through hole provided on the wiring board has a pressure holding portion and an introduction portion; the pressure holding portion and the introduction portion have an opening extending in the axial direction of the terminal, the introduction portion having a smaller cross-sectional area than the pressure holding portion; the pressure holding portion having an elastic force that becomes a holding force when pressed into the through hole; the introduction The portion has an elastic force weaker than that of the aforementioned pressure holding portion.

Furthermore, in the present invention, in an electronic device including a wiring board having a through hole, and a press-fit terminal press-fitted and held in the through-hole, the press-fit terminal has a pressure holding portion and an introduction portion;

The aforementioned pressure holding portion and the aforementioned introducing portion have openings extending in the axial direction of the aforementioned terminal, and the cross-sectional area of the aforementioned introducing portion is smaller than that of the aforementioned pressure holding portion;

The pressure holding portion has an elastic force that becomes a holding force when it is pressed into the through hole;

The introduction portion has an elastic force weaker than that of the pressure holding portion.

The introduction portion is formed to be thinner toward the front end, and a long opening is formed at the center of the terminal in the axial direction, and an elastic force is generated on the pressure holding portion and the introduction portion during press-fitting.

The cross-sectional area of the introduction part is smaller than that of the pressure holding part, and the opening of the introduction part is formed longer in the axial direction toward the front end, thereby adjusting the size of the cross-sectional area of the introduction part.

The opening portion is formed narrower in the area corresponding to the pressure holding portion and wider in the area corresponding to the introduction portion. In the opening portion, the area corresponding to the pressure holding portion is compensated for the The decrease in the elastic force of the pressure holding portion due to the reduction in the cross-sectional area of the introduction portion is formed to be narrow.

The above-mentioned wiring board is a laminated board, and multiple layers of glass fiber sheets are laminated with epoxy resin, and wiring is printed on the surface.

Furthermore, according to the wiring board of the present invention, a press-fit wiring board having a sheet-like base material and a through-hole press-fitting and holding the press-fit terminal, and an elastic material contained in the resin bonding the aforementioned sheet-like base material is formed.

In addition, in the electronic device of the present invention, it is configured to have a wiring board provided with a sheet-like base material and a through-hole for press-fitting and holding the press-fit terminal. Substrates containing elastic materials.

The elastic material contained in the press-fit wiring board is flexible particles dispersed in the resin of the substrate, and the flexible particles are any one of acrylic rubber, silicone rubber, and nitrile rubber, or a combination thereof.

The aforementioned elastic material is filled in the surface layer portion of the aforementioned substrate.

An inner peripheral surface of the through hole in the wiring board is made of a metal harder than copper.

Description of drawings

1A to 1C are diagrams illustrating states of stress generated in a substrate when a press-fit terminal is press-fitted into a through hole.

2A to 2C are diagrams illustrating an embodiment of a press-fit terminal according to the present invention.

3A to 3C are diagrams illustrating another embodiment of the press-fit terminal according to the present invention.

4 is a graph showing a change in insertion load with respect to an insertion stroke of a press-fit terminal, comparing the conventional case with the case of the present embodiment.

FIG. 5 is a graph showing a comparison between Examples and Conventional Examples with respect to the relationship between fracture length and compressive stress.

FIG. 6 is an exploded perspective view illustrating a mounting state of electronic components in a conventional vehicle-mounted electronic control device.

7A and 7B are diagrams illustrating a configuration in which press-fit terminals are press-fitted into through-holes of a wiring board on which electronic components are mounted.

8A to 8C are diagrams illustrating shapes of conventional press-fit terminals.

9 is a diagram illustrating a state in which a press-fit terminal is press-fitted into a through-hole of a wiring board.

Detailed ways

The present invention will be described below with reference to the accompanying drawings.

In order to clarify the effects of the present invention, first, the configuration of a general press-fit terminal and a press-fit-bonded wiring board used in electronic equipment without applying the present invention will be specifically described.

Here, the schematic assembly structure of the electronic control device according to the prior art is shown in FIG. 6 . The main part of the electronic control device 1 is accommodated in a connector body resin case 2 integrally formed with a connection case. The control connector 3 and the power connectors 4 and 5 are collectively arranged on one side of the connector body resin case 2 . Thereby, the electronic control device 1 can be electrically connected to the outside from only one direction.

In the connector body resin case 2, a control circuit part and a power circuit part are accommodated. A plurality of power electronic components 6 and 7 are included as a power circuit portion, and connection terminals 8 and 9 are mounted on the module portion on which these power electronic components are mounted. The connection terminals 8 and 9 are used for electrical connection with the control board 10 included in the control circuit portion. Here, the control board 10 is mounted on the upper surface side of the connector body resin case 2 . A plurality of through holes 11, 12 are provided at the end of the substrate 10, and after inserting the connection terminals 8, 9 into the through holes 11, 12, the control circuit and the power circuit are electrically connected by soldering or the like. A plurality of control electronic components 13 , 14 , 15 are mounted on the control board 10 . Also, after the control board 10 is mounted on the upper side of the connector body resin case 2, the upper side thereof is covered with a cover 16. As shown in FIG. On the other hand, a heat sink 17 for cooling the heat generated by the power electronic components 6 and 7 of the power circuit is attached to the bottom surface side of the connector body resin case 2 . Waterproof seals 18 and 19 are interposed between the lid 16 and the junction between the heat sink 17 and the connector body resin case 2 .

As described above, in the conventional vehicle-mounted electronic control device, during the assembly process of the electronic control device, the connection terminals 8 and 9 provided upright on the module incorporating the power circuit are inserted into the connection terminals 8 and 9 provided on the control board. After the through-holes 11, 12 on 10, the connection terminals 8, 9 are soldered to conductive members formed in the through-holes 11, 12 by plating or the like. As a result, the control board 10 is fixed in the connector body resin case 2 while the connection terminals 8 and 9 are electrically connected to the wiring pattern formed on the control board 10 .

However, in order to connect by welding, not only welding but also cleaning and other operations are required, which not only increases man-hours, but also deteriorates the working environment. In addition, in the case of connector terminals, there are many technical problems in soldering, and management man-hours have been increased in terms of converting the solder material from conventional eutectic solder to lead-free soldering.

Here, in order to reliably connect the connection terminal to the control board, in the above-mentioned conventional electronic control device, soldering may be performed after the connection terminal is inserted into the through-hole formed on the control board, but when the through-hole During soldering, since the hole on the side opposite to the side where the connection terminal is inserted is clogged with solder, it becomes difficult to confirm whether the through hole is in contact with the connection terminal, and it is difficult to find a bad connection. In addition, since the connection terminals and the control board are tightly fixed, for example, the vibration of the housing on which the actuator is mounted is directly transmitted to the control board, which adversely affects the electronic components mounted on the control board.

Therefore, as a countermeasure that can reliably connect the control board and the connection terminal, reduce man-hours, and realize a board connection that does not cause deterioration of the working environment, press-fit terminals are used for the connection terminals. . When this board connection is applied to an electronic control device, the state of the connection between the control board and the terminals in the electronic control device is shown in FIGS. 7A and 7B .

FIG. 7A shows a longitudinal section through a through hole of a control substrate. The control board 10 shown here is the same as that used in the electronic control device 1 shown in FIG. In FIG. 7A, these via holes are denoted by _H1 , _H2 . Although many through holes are actually provided, two are representatively shown here. The through holes are arranged at a pitch p. Further, a conductive member 18 formed by copper plating or the like is provided from the walls of the inner peripheral surfaces of the through holes H ₁ and H ₂ to the vicinity of the hole openings on the surface of the control substrate 10 . Use w to represent the via hole diameter.

On the other hand, in FIG. 7B , the press-fit terminals P ₁ , P ₂ embedded and erected in the terminal case for connection are shown. These press-fit terminals are arranged upright according to the number of through-holes provided on the control substrate 10, but in FIG. 7B, two press-fit terminals _P1 are shown corresponding to the through-holes _H1 , _H2 shown in FIG. 7A. , P ₂ , and are set upright at a position corresponding to the pitch p of the through holes. The lengths of the press-fit terminals P ₁ and P ₂ are adjusted so as to allow the control board 10 to be fixed at a predetermined position within the housing. W represents the maximum width of the press-fit terminal before press-fitting.

Here, a side view showing details of the pinhole type press-fit terminal is shown in FIG. 8A . In FIG. 8A , the orientation of the press-fit terminals shown in FIG. 7B is reversed. Thus, the press-fit terminal shown in FIG. 8A becomes press-fitted into the through-hole provided on the control substrate from above.

The press-fit terminals are formed by pressing a metal plate made of a conductive material such as a copper alloy, and are formed one by one. The press-fit terminal is integrally formed with a main body portion, a pressure holding portion, an introduction portion, and a front end portion along an axial direction. The elastic part at the time of press-fitting is formed by the pressure holding part and the introduction part, and the main body part, in the example of FIG. The lead-in portion is thinly formed so that when the press-fit terminal is pressed into the through-hole, the front end thereof is easily inserted.

Along the longitudinal direction of the axial center of the press-fit terminal, an opening formed simultaneously with the punching of the metal plate to penetrate is provided. The pressure holding portion and the introduction portion are formed by the opening, and the width W of the pressure holding portion indicated by the line A-A is the widest among the terminals. The width of the introduction portion gradually narrows toward the front end.

In FIG. 8B , a cross section along line A-A as part of the pressure holding portion is shown, and a cross section along line B-B as part of the introduction portion is shown in FIG. 8C . The sizes of these cross-sectional areas are the same in the pressure holding part and the introduction part.

When the press-fit terminal shown in FIG. 8A is pressed into the through-hole, if the press-fit terminal is lowered from above, or by pushing up the control substrate, the vicinity of the B-B line of the introduction part first contacts the opening periphery of the through-hole to apply load and produce elastic deformation. Furthermore, if the load continues to be applied, the pressure holding portion is pressed into the through hole. Here, the press-fit allowance of the press-fit terminal to the through hole is (W-w).

Here, a state in which the press-fit terminals P ₁ , P ₂ shown in FIG. 7B are press-fitted into the through holes H ₁ , H ₂ of the control substrate 10 shown in FIG. 7A is shown in FIG. 9 . The pressure holding portion of the press-fit terminal shown in FIG. 8A, as shown in FIG. 9, is completely pressed into the through hole, the control substrate 10 is held in a position close to the terminal module for connection, the control substrate is fixed, and, The pressure holding portion is in close contact with the conductive material 18 in the through holes H ₁ , H ₂ to form an electrical connection.

However, when the press-fit terminal is press-fitted into the through-hole provided on the control board, the opening of the through-hole of the control board shown by the circle line in FIG. of minor damage. Even in general electronic equipment, a joining method by press-fit terminals is widely used, but in this case, it is necessary to focus on managing the diameter tolerance of the through-hole of the substrate so that the terminals are press-fitted. However, even in this case, since the terminal needs to be press-fitted to obtain a holding force with the substrate, an unnecessary load is applied to the substrate. Therefore, when press-fitting the press-fit terminal, a large force acts toward the substrate surface at the opening of the through hole, and the base material such as peeling of the laminated sheet occurs near the periphery of the opening of the through hole. Damage caused by destruction.

As explained above, in the conventional press-fit joint used in the electronic control unit, when the press-fit terminal is press-fitted into the through-hole provided on the wiring board, there is a risk of damage to the wiring board itself. Such flaws as unnecessary loads.

Therefore, in the present invention, the shape of the press-fit terminal used in the press-fit joint is studied, and a terminal that can be applied to a commonly used wiring board and can suppress the burden generated when the terminal is pressed into the wiring board has been developed. , and can maintain the size of the holding force after press-fitting, a press-fit terminal with higher connection reliability than before.

Next, embodiments of the press-fit terminal of the present invention will be described with reference to the drawings.

Therefore, first, before describing an embodiment of the press-fit terminal of the present invention, a method of thinking for completing the press-fit terminal is shown in FIGS. 1A to 1C . FIG. 1A shows a state where a prior art press-fit terminal P shown in FIG. 8A is pressed into a through hole _H1 or _H2 of a control substrate 10 shown in FIG. 7A. In FIG. 1A , to simplify the drawing, the press-fit terminal P is shown as a simple shape, and the illustration of the conductive member 18 inside the through hole _H1 or _H2 is omitted.

FIG. 1A shows the state where the press-fit terminal P is pressed into the through hole H. As shown in FIG. When the press-fit terminal P is inserted into the through hole H and the introduction portion contacts the opening peripheral portion of the through hole H, the insertion stroke is set to 0 mm. Then, force is applied to the press-fit terminal P, and when it starts to be pressed into the through hole H via the introduction portion and the pressure holding portion, the insertion stroke is set to 0.6 mm. Although not shown, afterward, the pushing operation is continued, and the insertion stroke becomes longer. A constant pushing force is applied to the terminal during the pressing operation.

In FIG. 1B , changes in the load applied to the control substrate 10 when the press-fit terminal P is pressed into the through hole H as shown in FIG. 1A are shown. The horizontal axis represents the insertion stroke (mm), and the vertical axis represents the load (N). A load curve shown by a solid line represents a change in load during the press-fit operation of the press-fit terminal P shown in FIG. 1A . It can be seen from the figure that the load becomes the peak value near the insertion stroke of 0.6 mm.

In FIG. 1C , changes in the stress occurring at the opening peripheral portion of the through-hole H of the substrate are shown in the stress curve corresponding to the load curve. The horizontal axis represents the insertion stroke (mm), and the vertical axis represents the generated stress (N/mm ² ). As can be seen from this stress curve, the magnitude of the generated stress becomes maximum around the insertion stroke of 0.6 mm, and decreases as the press-fitting operation continues. Here, when trying to compare with the design reference value of the substrate, as shown in FIG. 1C , the maximum value near the insertion stroke of 0.6 mm exceeds the design reference value of the substrate. Therefore, it is considered that an excessive stress is generated at the periphery of the opening of the through-hole provided in the substrate, and the laminated structure of the periphery is broken.

Therefore, in order not to damage the opening periphery of the through-hole H when the press-fit terminal P is pressed into the through-hole H, it is sufficient that the maximum value of the stress curve does not exceed the substrate design reference value. From this, it can be seen that, as shown in FIG. 1B, with respect to the curve of the solid line having the maximum value of the generated stress, as long as the shape of the press-fit terminal can make the change of the load with the insertion stroke become the stress curve shown by the dotted line, then Can.

Based on the above findings, the press-fit terminal according to this embodiment is formed into a shape having two-stage elastic characteristics in which the stress applied to the substrate by the introduction portion is reduced during press-fitting, and the holding force is maintained or enhanced by the pressure holding portion. The press-fit terminal of this embodiment will be described in detail below with reference to FIGS. 2 and 3 .

Fig. 2A shows a press-fit terminal in which the elastic force at the pressure holding part is the same as that of the pinhole type press-fit terminal P shown in Fig. 8A, and the elastic force at the introduction part is smaller than that of the pressure holding part. side shape. The press-fit terminal shown in FIG. 2A is also the same as that in FIG. 8A , and its entirety is integrally formed by pressing a metal plate. The thickness of the press-fit terminal P is taken to be uniform.

The press-fit terminal is integrally stamped with a main body, a pressure holding portion, an introduction portion, and a front end, and has a long axially penetrating opening in the center, as in the case of FIG. 8A . The cross-sectional area at the A-A line of the pressure holding part is shown in Figure 2B, and the elastic force of the pressure holding part is the same as the cross-sectional area of the pressure holding part of the press-fit terminal shown in Figure 8A, which is the same as that shown in Figure 8B The cross-sectional area is the same.

In the press-fit terminal P shown in FIG. 2A , in order to make the elastic force of the introduction part weaker than that of the pressure holding part, the length of the through-opening in the axial direction is longer than that of the conventional one shown by the dotted line. The opening provided in the terminal is extended toward the front end. By forming such an opening, as opposed to the case where the pressure holding portion and the introduction portion have the same cross-sectional area in the conventional press-fit terminal of FIG. 8A , in the press-fit terminal of this embodiment shown in FIG. 2A , as shown in FIG. 2C , the cross-sectional area at the B-B line of the introduction part is smaller than the cross-sectional area of the pressure holding part.

In this way, according to the press-fit terminal of the present embodiment shown in FIG. 2A , by making the cross-sectional area of the introduction portion narrower than that of the pressure holding portion, the elastic force of the introduction portion is weakened, and the occurrence of stress shown in FIG. 1C can be reduced. Stress maximum in the curve. Taking the case of the press-fit terminal of this embodiment as Example 1, the load curve thereof is shown in FIG. 4 . Compared with the load curve according to the conventional case, it can be seen that the load generated by the introduction part can be reduced, and the damage of the substrate during press-fitting can be suppressed. Furthermore, the elastic force of the pressure holding portion is formed so that a necessary holding force can be ensured without changing the press-fit margin of the conventional press-fit terminal.

Next, another embodiment of the shape of the opening that weakens the elastic force of the introduction portion will be described with reference to FIG. 3 . In the press-fit terminal shown in FIG. 2A , the press-fit margin remains unchanged from the past, and the length of the long opening in the axial direction that passes through is extended toward the front end to weaken the elastic force of the introduction part. In the embodiment of FIG. 3 , the point of not changing the press-fit allowance is the same as that of the aforementioned embodiment, but the length of the long opening along the axial direction also keeps the length of the conventional opening unchanged, and the opening The shape of the part is worked up and down to change the elastic force of the introduction part.

The press-fit terminal P used in another embodiment shown in FIG. 3A is the same as the pinhole-type press-fit terminal P shown in FIG. 8A as an overall shape, and is integrally formed by punching a metal plate. overall. The thickness of the press-fit terminal P is uniform.

The press-fit terminal P is integrally formed by stamping a body part, a pressure holding part, an introduction part, and a front end part, and an opening part penetrating long in the axial direction is provided in the center, and the length of the opening part is the same as that shown in FIG. The same is true for 8A. In addition, in FIG. 3A, the conventional opening part is shown by the dotted line. The cross-sectional area at the line A-A of the pressure holding part is shown in FIG. 3B, and the cross-sectional area at the line B-B of the introduction part is shown in FIG. 3C.

In the press-fit terminal P of FIG. 3A, in order to make the elastic force of the introduction part weaker than that of the conventional pressure holding part, as shown in FIG. The cross-sectional area of the B-B line in this part. However, if the width of the introduction portion is narrowed to reduce its cross-sectional area to obtain a predetermined elastic force, the shape of the opening is as shown in FIG. . In this way, if the cross-sectional area at the line A-A of the pressure holding portion remains the same as that of the conventional pressure holding portion, the original holding force may not be exhibited.

Therefore, in the press-fit terminal P of another embodiment shown in FIG. 3A , as compensation for the decrease in the holding force, the opening area of the opening of the pressure holding portion is narrowed so that the cross-sectional area of the line A-A is smaller than Conventionally, this cross-sectional area was large. This situation is represented in Figure 3B.

In this way, if the press-fit terminal of the other embodiment shown in FIG. 3A is used, the cross-sectional area of the introduction portion is smaller than that of the pressure holding portion, thereby weakening the elastic force of the introduction portion, and reducing the force shown in FIG. 1C . The stress maximum in the stress curve occurs. A load curve in the case of a press-fit terminal according to another embodiment is shown in FIG. 4 as Example 2. As shown in FIG. Comparing with conventional load curves, it can be seen that the load generated by the introduction part can be reduced, and the damage of the substrate during press-fitting can be suppressed. Furthermore, as for the elastic force of the holding part, by increasing the cross-sectional area of the pressure holding part to compensate for the decreased elastic force, the holding force can be ensured without changing the press-fit margin of the conventional press-fit terminal.

Although in the press-fit terminal described above, the case of the pinhole type has been described as an example, other forms, such as Z-type and movable type press-fit terminals, can also be made to have the opening of the introduction part. The two-stage elastic characteristic that the elastic force is weaker than the elastic force of the pressure holding portion reduces damage to the substrate that occurs when the terminal is pressed into the through hole.

In addition, in the press-fit terminal of the above-mentioned embodiment, the shape of one opening extending long in the axial direction in the center is changed, and the cross-sectional area of the introduction part is adjusted, thereby weakening the elastic force of the introduction part. , but it is also possible to separate the opening where the elastic force is generated in the pressure holding part and the introduction part, and even if two openings are provided corresponding to the introduction part, the elastic force of the introduction part can be weakened.

Furthermore, although in the press-fit terminal according to the above-mentioned embodiment, since the terminal formed by punching a metal plate is used, the entire terminal has a uniform thickness. The application of the two-stage elastic characteristic method such that the elastic force of the part is weak does not have to be limited to the case of uniform thickness. Because of the uniform thickness, the elastic force of the introduction part can be changed by adjusting the opening shape of the opening part. As a way of changing the cross-sectional area of the introduction part and the pressure holding part, it can also be realized by changing the thickness of the terminal. For this purpose, methods such as press working and plating on appropriate parts can be mentioned.

As mentioned above, the embodiment of the press-fit terminal of the present invention has been shown, and the situation of suppressing the occurrence of stress on the press-fit-bonded wiring board by studying the structure of the press-fit terminal has been described. However, referring to the drawings, A press-fit-bonded wiring board according to the present invention, in which the structure of the press-fit-bonded wiring board itself is contrived and the stress generated on the wiring board is relieved, will be described.

In the press-fit-bonded wiring board according to the present invention, in the case where the press-fit terminal is press-fitted into a through-hole provided on the wiring board in the electronic control device to perform electrical bonding, the terminal press-in can be absorbed. The press-fit bonding wiring board that suppresses the external stress during the time and suppresses the load that occurs inside the board. In addition, there is also provided a substrate structure that can still use the conventional press-fit terminals and can reduce the stress from the terminals received by the board.

When the control board is assembled into the electronic control unit, when the press-fit terminal is pressed into the through hole provided on the control board, the entrance part of the through hole provided on the control board may be caused by the press-fit terminal. The fact that the slight damage caused by the stress concentration during the time has been mentioned above. This situation is shown in FIG. 9 , where such damage occurs around the openings of the through-holes H ₁ , H ₂ of the control substrate 10 surrounded by circled lines in the figure.

Also in general electronic equipment, a method of bonding by press-fit terminals is widely used. In this case, too, the diameter tolerance of the through-hole of the substrate is controlled so that the terminal is press-fitted. However, since the terminal is press-fitted to obtain a holding force with the substrate, an unnecessary load is applied to the substrate, which occurs. Damage during pressing.

In general, since a control substrate adopts a laminated structure in which a plurality of sheets impregnated with glass fibers combined vertically and horizontally are stacked and compacted and cured, when the press-fit terminal is pressed in, the Since a large force acts on the periphery of the opening in the direction of the substrate surface, damage may occur near the periphery of the through hole due to damage to the base material such as peeling of laminated sheets. Furthermore, when a method of strengthening the elasticity of the press-fit terminal such as a large press-fit margin is adopted in order to strengthen the fixed holding of the press-fit terminal, damage during press-fitting becomes more remarkable.

However, in harsh working environments such as electronic control devices installed in the engine room of automobiles, such as high ambient temperature, high humidity, and strong vibration, damage during press-fitting will affect the characteristics of the substrate. If there is damage on the control substrate during press-fitting, when the control substrate is placed in a high-temperature and humid environment, the damaged part becomes easy to absorb moisture, and as a result, copper ions of the conductive material are eluted, which accelerates the deterioration of the insulation of the substrate. Especially recently, in order to obtain a variety of control functions in the electronic control device, the density of the control board is high and even the miniaturization is sought, the electrical connection parts of the control board are increased, and the distance between the through holes is reduced. This is a very serious problem of accelerating the deterioration of the insulating properties of the substrate.

In addition, especially in the case of a control board of an electronic control device installed in an engine room or the like that vibrates strongly, it is necessary to further strengthen the holding force by the press-fit terminals. Therefore, when the press-fit allowance is increased in order to increase the holding force generated by the press-fit terminal, the burden at the time of press-fit is increased instead. The press-fit margin can suppress the load (load), but there is a problem that the holding force of the press-fit terminal is reduced.

Therefore, as a method for solving these problems, in the present invention, there is provided a method that can perform electrical wiring in a through hole provided on a wiring board in an electronic control device used, for example, to press-fit a terminal in a high-temperature environment. In the case of bonding, when the terminal is pressed in, it absorbs external stress and suppresses the burden on the substrate. In addition, it also provides a press-fit terminal that can still be used in the past, and can absorb the stress on the substrate. The substrate structure of the stress from the terminals.

Therefore, first, before describing the press-fit-bonded wiring board according to the present embodiment, the way of thinking to complete the improvement of the press-fit-bonded wiring board is shown in FIGS. 1A to 1C . The concept of completing the improvement of the press-fit-bonded wiring board is the same as that of the press-fit terminal of the present embodiment described above.

As shown in the load curve shown by the solid line in FIG. 1B, when the press-fit terminal P is pressed into the through hole H, the load applied to the control substrate 10 changes, and the load forms a peak value near the insertion stroke of 0.6 mm. . In FIG. 1C , changes in the stress generated at the opening peripheral portion of the through-hole H of the substrate are shown corresponding to the load curve. From this stress curve, it can be seen that the magnitude of the generated stress becomes maximum near the insertion stroke of 0.6 mm, and decreases as the press-fitting operation progresses.

Here, when the design reference value of the conventional board is as shown in the figure, the maximum value at the vicinity of the insertion stroke of 0.6 mm exceeds the board design reference value when compared with the design reference value. Therefore, it is considered that an excessive stress was generated at the periphery of the opening of the through-hole provided in the substrate, and the laminated structure of the periphery was broken.

Therefore, in order not to damage the opening periphery of the through hole H when the press-fit terminal P is pressed into the through hole H, it is only necessary that the maximum value of the stress curve does not exceed the board design reference value.

Based on the above knowledge, the press-fit wiring board of this embodiment is formed as a board that can reduce the external stress applied to the board when the press-fit terminals are respectively press-fitted into a plurality of through holes provided on the wiring board. For the structure, in order to reduce the stress, the substrate itself of the laminated structure is provided with an elastic structure. As a specific method, the elastic material is filled in the resin bonding the sheet-like base material of the substrate.

Next, the press-fit-bonded wiring board of this embodiment will be described. There are various methods for filling the resin of the sheet-like base to which the substrate is bonded, such as epoxy resin, with an elastic material.

For example, when a prepreg layer obtained by impregnating and drying an epoxy resin varnish containing a curing agent in a sheet-shaped base material and a metal foil placed on the surface thereof are heated and pressurized to be integrated, the Epoxy resin-incompatible rubber elastic fine particles are dispersed in a part or all of the prepreg layer to form a prepreg layer obtained by impregnating and drying an epoxy resin varnish in a sheet-like base material.

Here, the dispersed microparticles have rubber elasticity that is incompatible with the epoxy resin in the varnish. The material of the particles is one of acrylic rubber, silicone rubber, and nitrile rubber, or a combination thereof. choose among things.

Next, when such microparticles are dispersed in the resin and the resin constituting the substrate is elastic, when it is used for press-fit bonding of through holes, damage occurs in the substrate when the press-fit terminal is press-fitted. The situation is shown in Figure 5. In the graph of FIG. 5 , the case of a press-fit wiring board with elastic resin according to this embodiment is shown as an example. For comparison, a conventionally used epoxy resin composite board (FR-4)—for example, The case of the glass fabric resin substrate is conventionally illustrated.

In Fig. 5, as the damage that occurs on the substrate when the press-fit terminal is press-fitted into the through-hole provided on the substrate, the results of measuring the fracture length such as peeling of the sheet-like base material are shown, which are different from those assumed to be in the through-hole. Unlike the substrate test piece in which stress was applied to the wall surface of the substrate, the failure length was measured by applying a load in a direction parallel to the lamination surface of the sheet-shaped base material of the substrate. In the graph of FIG. 5 , the solid circles represent the measurement results in the conventional example, and the solid square points represent the measurement results in the embodiment. A thick solid line corresponds to an example, and a thin solid line corresponds to a conventional example. The lines reflect the trends generated from the plots of the individual measurements.

Here, when observing the progression of the failure length in the conventional example, the failure length increases as the stress applied to the substrate increases. A case where the degree of progression of the length of destruction is suppressed is shown. The difference in the occurrence and result of the fracture is considered to be due to the filling of the elastic material in the resin. If the result of the destruction length is due to the difference in the type of microparticles filled, there will not be such a big difference compared with the embodiment in FIG. 5 .

In the substrate used in the conventional examples, when hard-fit bonding is performed, only the holding force with the substrate is focused, and damage to the substrate when the press-fit terminal is pressed into the through hole is not considered. Therefore, as the terminal density increases, the intervals between the through holes become shorter, and the above-mentioned progress of the failure length becomes a major obstacle in improving the insulation reliability of the substrate. As a result, for use in a high-temperature environment, the through-hole intervals have to be designed to be wider or the holding force of the press-fit terminals to be designed to be small in consideration of the destruction length.

In contrast to this conventional example, in the example in which the elastic material is filled in the resin, it is possible to press the press-fit terminal into the through hole as shown in FIG. Since the progression of the fracture length is suppressed to a low level, it is possible to obtain a substrate that withstands stress during press-fitting. Therefore, even if the via hole pitch is shortened, the insulation reliability of the substrate can be ensured.

For example, in the case where the via hole pitch (inter-terminal pitch) is 300 μm, the limit of the destruction length at this time is 150 μm. In FIG. 5, this range is shown as a hatched permissible failure length region. In the substrate of the conventional example, for example, the through-hole pitch is designed to be 300 μm. In order to obtain the necessary insulation reliability, the holding force of the press-fit terminal must be weakened to reduce the stress when the terminal is press-fitted. Generally, since the stress generated when the terminal is pressed into the through hole needs to be about 400 to 500 N/mm ² , the substrate of the conventional example cannot meet this requirement. In addition, in FIG. 5, this generated stress is shown as _f1 .

In contrast, in the case of the substrate of the embodiment, since the resin is filled with an elastic material, the external stress applied to the substrate can be relaxed and absorbed, thereby enhancing the strength of the substrate, as shown in FIG. 5 . As shown in the stress _f2 , for example, even if a stress of 600 μm is applied, the fracture length can be suppressed to 150 μm or less, which fully satisfies the above requirements.

In the description so far, the case where the elastic material of the wiring board is filled in the entire board has been taken as an example, but in the part where it is necessary to absorb and relax the external stress applied to the board, as shown in FIG. 1C, the For the press-fit terminal, focus on the vicinity of the press-fit entrance of the through-hole formed on the substrate, and the filling of the elastic material into the resin may also be performed on the surface of the substrate.

In addition, when the stress that occurs when the terminal is pressed into the through hole is large, in addition to filling the resin with an elastic material, a metal harder than copper (such as nickel, palladium, etc.) is used for the conductive material formed on the inner surface of the through hole Rhodium, etc.) to form a high strength, bear a part of the stress when the terminal is press-fitted, thereby dispersing the stress concentration, improving the stress resistance performance, and improving the reliability of the substrate.

Furthermore, although in each of the above-mentioned embodiments, it is applied to control circuit devices of electronic control devices such as automobiles, the present invention is not limited to related applications, and other circuit boards, such as control circuit boards of labor-saving machines , In the control circuit board of communication equipment, it can also be used, and the same effect can be obtained.

As described above, in the press-fit terminal of the present invention, since the elastic force of the introduction portion of the terminal is formed to have two-stage elastic characteristics that are weaker than the elastic force of the pressure holding portion, when the terminal is pressed into the substrate, When inside the through-hole formed above, the burden (load) on the opening peripheral portion of the through-hole can be suppressed.

Since the pressing force applied to the press-fit terminal is not weakened at the time of pressing, and the pressing force is increased when the pressure holding part is pressed in, but the press-fit terminal itself has two stages of elastic characteristics, it is possible to The mating terminal is press-fitted with a constant pressing force from the time of press-fitting to the end of the press-fitting operation, which can suppress the load inside the substrate during press-fitting.

Furthermore, in the press-fit terminal of the present invention, since the elastic force of the press-holding portion of the terminal can maintain a sufficient holding force when pressed into the through-hole, even if the diameter tolerance of the through-hole is not strictly reduced, etc. Management Using the normal substrate in its original state, in addition to not placing a load on the substrate, the terminal can also be used to firmly hold the substrate, and it is possible to ensure electrical connection with the wiring provided on the substrate.

In addition, since the load when the press-fit terminal is inserted is halved, it is possible to reduce the force of the insertion jig of the press-fit terminal.

Furthermore, in the press-fit wiring board of the present invention, since the elastic material is filled in the resin bonding the sheet base material of the board, it is not necessary to change the pressure to be pressed into the through hole provided on the board. By matching the shape of the terminal, etc., it is possible to ensure the retention force in the conventional press-fit joint, and to improve the insulation reliability between through holes. Therefore, the press-fit-bonded wiring board can be used as a control board of an electronic control device in a severe environment of high temperature, high humidity, and strong vibration.

In addition, by filling the resin with an elastic material, external stress applied to the substrate can be relaxed and absorbed. Therefore, even if the conventional terminal is used, that is, even if the conventional terminal is not improved, a good effect can be obtained. In addition, in order to manage the press-fit margin of the conventional substrate, although the diameter tolerance of the hole of the printed wiring substrate , For example, it is necessary to be in the range of 50 μm, but it can be managed in the range of 150 μm to 200 μm, and the degree of freedom in the design of the printed wiring board can be increased. Furthermore, the interval between the through holes can be shortened, and a high-density design of the control substrate can be performed.

Claims (14)

1. press-fit terminal, this terminal are to be pressed into the press-fit terminal that remains in the through hole of being located on the wiring substrate, it is characterized in that,

Have pressure retaining parts and introduction part;

Aforementioned pressure maintaining part and aforementioned introduction part have peristome, and this peristome extends axially along aforementioned terminal, the sectional area ratio aforementioned pressure maintaining part of aforementioned introduction part little;

The aforementioned pressure maintaining part has the elastic force that becomes confining force when being pressed into aforementioned through-hole;

Aforementioned introduction part has than the elastic force a little less than the elastic force of aforementioned pressure maintaining part.

2. an electronic equipment possesses the wiring substrate with through hole and is pressed into the press-fit terminal that remains in this through hole, it is characterized in that,

Aforementioned press-fit terminal has pressure retaining parts and introduction part;

Aforementioned pressure maintaining part and aforementioned introduction part have peristome, and this peristome extends axially along aforementioned terminal, the sectional area ratio aforementioned pressure maintaining part of aforementioned introduction part little;

The aforementioned pressure maintaining part has the elastic force that becomes confining force when being pressed into aforementioned through-hole;

Aforementioned introduction part has than the elastic force a little less than the elastic force of aforementioned pressure maintaining part.

3. press-fit terminal as claimed in claim 1 is characterized in that aforementioned introduction part forms carefullyyer towards front end.

4. press-fit terminal as claimed in claim 1, the sectional area that it is characterized in that aforementioned introduction part is along with reducing towards aforementioned front end.

5. press-fit terminal as claimed in claim 1 is characterized in that aforementioned peristome forms narrowlyer in the zone corresponding to the aforementioned pressure maintaining part, form in zone corresponding to aforementioned introduction part broad.

6. press-fit terminal as claimed in claim 5, it is characterized in that the aforementioned areas in the aforementioned peristome corresponding to the aforementioned pressure maintaining part, for the elastic force that compensates the aforementioned pressure maintaining part that reduces to cause because of the aforementioned sectional area that makes aforementioned introduction part descends, form narrowlyer.

7. press-fit terminal as claimed in claim 1 is characterized in that aforementioned wiring substrate is the substrate that is laminated.

8. press-fit terminal as claimed in claim 1 is characterized in that aforementioned wiring substrate is made of the multilayer board that is laminated with the compound glass fibre sheet material, has the printing distribution on this wiring substrate surface.

9. an interference fit engages wiring substrate, is made of flat substrates, possesses press-fit terminal is pressed into the through hole that keeps this terminal, and contains elastomeric material at the resin that is used in conjunction with aforementioned flat substrates.

10. electronic equipment has by flat substrates and constitutes, and possesses the wiring substrate that press-fit terminal is pressed into the through hole that keeps this terminal;

Aforementioned wiring substrate contains elastomeric material at the resin that is used in conjunction with aforementioned flat substrates.

11. interference fit as claimed in claim 9 engages wiring substrate, it is characterized in that aforementioned elastic is the elastic granule that is dispersed in the resin of substrate.

12. interference fit as claimed in claim 11 engages wiring substrate, it is characterized in that aforementioned elastic granule is any one in acrylic rubber, silicon rubber, the acrylonitrile-butadiene rubber, or its multiple combination.

13. interference fit as claimed in claim 9 engages wiring substrate, it is characterized in that aforementioned elastic, is filled in the top layer part of aforesaid base plate.

14. interference fit as claimed in claim 9 engages wiring substrate, it is characterized in that the inner peripheral surface of aforementioned through-hole has the metal harder than copper.

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