JPH11280722A - Caulking member, its manufacture and large current circuit substrate provided with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a caulking member, its simple manufacturing method and a large current circuit substrate having the caulking member capable of greatly increasing reliability and reducing manufacture cost. SOLUTION: In this caulking member, copper is machined to a cylindrical form and a flange part 8 with uniform thickness by cold forging or grinding, followed by annealing only to a part as a caulking part 16 to produce a fastener 15 having a part with high hardness and a part with low hardness. Finally, after the fastener 15 is inserted into the through hole 5 of a printed board 4, load is applied to the fastener 15 from the upper end of the fastener 15 by using a hydraulic press or the like. As a result, the part with low hardness expands outward for form the caulking part 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caulking member, a method of manufacturing the same, and a large current circuit board for forming a large current circuit.

[0002]

2. Description of the Related Art Conventionally, a large current circuit board device is a device in which a bus bar is attached to a printed circuit board and circuit components are connected, and soldering is used as an attachment method, but the number of processes is increased. To solve this problem, the electrical and mechanical reliability was low. To solve this problem, Japanese Patent Publication No. Hei 7-16090 discloses a method in which a bus bar and circuit components are mounted on a printed circuit board by using bolts with nuts that are fasteners. What connects is disclosed.

FIG. 6 is a cross-sectional view showing a conventional large current circuit board disclosed in Japanese Patent Publication No. 7-16090. In the drawing, 1 is a circuit component, 2 is a lead terminal fixed to the circuit component 1, 3 is a screw thread provided on the lead terminal 2, 4 is a printed board, 5 is a through hole provided on the printed board 4, 6 Is the fastener, 7 is the swaged part of the fastener 6, 8
Is a flange portion of the fastener 6, 9 is, for example, 12 mm in width,
A bus bar formed of a long and thin copper plate having a thickness of 1.2 mm and through which a large current can flow, 10 is a through hole provided in the bus bar 9, and 11 is a screw for fixing the printed board 5 and the bus bar 9 to the lead terminal 2. .

FIG. 7 is a sectional view showing a conventional fastener before caulking. As shown in the figure, the fastener 6 is a cylindrical body having the same outer diameter except for the flange 8 at the tip. The tubular body has a two-stage plate thickness, and the plate thickness in the vicinity of the flange portion 8 is smaller than the plate thickness in the distant portion. Hereinafter, a portion near the flange portion 8 is referred to as a thin portion 6a, and a portion remote from the flange portion 8 is referred to as a thick portion 6b.

The large-current circuit board shown in FIG. 6 forms a caulked portion on the fastener 6 shown in FIG. 7 so that a large current supplied from the bus bar 9 can be passed through the fastener 6 from the front side to the back side of the printed circuit board 4. Is to be energized. Next, a method for manufacturing a large current circuit board will be described by describing a method for caulking a fastener.

First, at a desired position of the printed circuit board 4 shown in FIG.
A through hole 5 which is about m larger is provided, and a fastener 6 is inserted into the through hole 5. Next, as shown in FIG. 7, a load 12 is applied to the fastener 6 from the upper end of the fastener 6 using a hydraulic press or the like. As a result, a stress is applied in the axial direction 13 of the fastener 6 and a force acts so that only the thin portion 6a expands in the outer peripheral direction. As shown in FIG. 6, a crimped portion 7 composed of the thin portion 6a is formed on the fastener 6. Is done.

Thereafter, a screw 11 is inserted into the through hole 10 of the bus bar 9 and the cavity of the fastener 6 and screwed into the screw hole 3 of the lead terminal 2 to complete a large current circuit board.

[0008]

The conventional large current circuit board is constructed and manufactured as described above. With the increase in capacity of semiconductor switching elements such as IGBT and IPM,
If the design of the fastener is not changed, for example, when the current carrying capacity is increased, the contact area of the swaged portion of the fastener must be increased to increase the fixing force. For this purpose, it is necessary to increase the crimping load and enlarge the crimped portion of the fastener. Was.

Further, even if the number of fasteners is increased by changing the design of the fasteners, the swaging load must be increased in order to swage the fasteners. There was a problem that had to be.

Further, as shown in FIG. 7, a thin portion 6a and a thick portion 6b must be formed in the fastener 6.
Holes must be formed twice when the fastener 6 is formed, so that the manufacturing method is complicated and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a caulking member capable of greatly improving reliability, a simple manufacturing method and reducing a manufacturing cost, a manufacturing method thereof, and a large current circuit. It is intended to provide a substrate.

[0012]

According to a first aspect of the present invention, there is provided a caulking member wherein the hardness of the first body is lower than the hardness of the second body.

[0013] The caulking member according to claim 2 of the present invention comprises:
The thickness of the first body in the radial direction is smaller than the thickness of the second body in the radial direction.

According to a third aspect of the present invention, there is provided a caulking member,
The hardness of the first body is lower than the hardness of the second body, and the hardness of the first body is gradually increased from the side closer to the flange.

A large current circuit board according to a fourth aspect of the present invention is provided with a caulking member serving as one or both of a printed board and a busbar for supplying a large current as a plate-shaped member.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a caulking member, comprising processing a conductive metal to form a cylindrical body having a uniform thickness and an axial end of the body from the body. Forming a flange portion protruding radially outward, and dividing the body into a first body near the flange and a second body far from the flange; Annealing the body only so that the hardness of the first body is lower than the hardness of the second body.

According to a sixth aspect of the present invention, there is provided a method for manufacturing a caulking member, comprising processing a conductive metal, connecting the first body and the first body, and having a radial thickness of the first body. A cylindrical body composed of a second body thicker than the radial thickness of the part, and a flange projecting radially outward from the first body at one axial end of the first body; Forming a part and
Annealing the entire body so that the hardness of the first body is lower than the hardness of the second body.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a caulking member, comprising processing a conductive metal to form a cylindrical body and one axial end of the body radially outward from the body. The step of forming the protruding flange portion is a processing step by cold heading.

According to a second aspect of the present invention, there is provided a method for manufacturing a caulking member, comprising processing a conductive metal to form a cylindrical body and one axial end of the body radially outward from the body. The step of forming the protruding flange portion is a processing step by grinding.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a sectional view showing a large current circuit board according to Embodiment 1 of the present invention. In the figure, 14 is an electric component such as a semiconductor switching element, 15 is a fastener as a caulking member, 16 is a caulking portion of the fastener 15, 8 is a flange portion of the fastener 15, 9 is, for example, a 12 mm wide and 1.2 mm thick elongated member. A bus bar made of a copper plate and capable of flowing a large current, 1
Reference numeral 0 denotes a through hole provided in the bus bar 9, 4 denotes a printed board as a board member, 5 denotes a through hole provided in the printed board 4, and 17 denotes a screw for fixing the bus bar 9 and the fastener 15 to the electric component 14. .

FIG. 2 is a sectional view showing a fastener before swaging according to the first embodiment of the present invention. As shown in the figure, the fastener 15 is a cylindrical body having the same outer diameter except for the flange portion 8 at the tip, 15a is a first body portion having a low hardness, and 15b is a second body portion. It is a part with high hardness. Further, reference numeral 12 denotes a load when the fastener 15 is crimped, and reference numeral 13 denotes an axial direction of the fastener 15.

Next, a method of manufacturing the fastener 15 will be described. For example, the fastener 15 is made of a conductive metal such as C1100, C1220, C1201, or the like.
The copper shown in 3100 is used as a raw material, and is processed into a cylindrical shape having a uniform thickness by grinding or cold forging (press). At this time, the fastener 15 is formed to have, for example, a length of 13.5 mm, an outer diameter of 9.5 mm, and an outer diameter of the flange portion of 12 mm. Thereafter, annealing is performed only on the portion which will later be the crimped portion 16, and the low hardness portion 15a and the high hardness portion 15a
and b.

Here, when the copper is manufactured by cold heading, since the copper is hit or stretched to cause plastic deformation to form the tubular shape of the fastener 15,
The part of the copper that has undergone plastic deformation undergoes work hardening and becomes hard, and the crystal grains become fine. Even when copper is manufactured by grinding, if the processing speed is increased, copper hardens due to work hardening due to heat and physical impact generated during the processing, and its crystal grains become fine.

This work hardening causes the hardened and fine crystal grains of copper to be subjected to an annealing treatment only on the portion which will later become the caulking portion 16 to remove internal strain during work hardening and cause recrystallization of copper. Softens copper. In this annealing process, heat is preferably applied only to the portion 15a of the fastener 15 where the annealing process needs to be performed using a pulse excimer laser, a pulse CO ₂ laser, an oxygen burner, or the like. When the size of the fastener 15 is large, annealing may be performed with only the necessary portion 15a immersed in oil.

The conditions of the annealing vary depending on the degree of work hardening of the copper of the fastener 15. For example,
When the fastener 15 is formed by processing the C1100 material by cold heading and annealing using oil, the temperature is preferably 150 to 350 ° C. and the time is preferably about 15 minutes to 6 hours.

In the case of the first embodiment, the C1100 material is worked by cold heading, and then annealed in oil at 150 ° C. for 3 hours to obtain a low hardness portion 1.
A fastener 15 having hardnesses of 5a and the high hardness portion 15b of about 80 and 120 in Vickers hardness, respectively, was manufactured.

Next, a method of manufacturing a large current circuit board using the fastener 15 will be described. First, as shown in FIG. 2, the fastener 15 is inserted into the through hole 5 provided in the printed circuit board 4. The size of the through hole 5 is larger than the outer diameter of the fastener 15 by about 0.1 mm to 0.5 mm.

Next, the fastener 1 is pressed using a hydraulic press or the like.
A load 12 is applied to the fastener 15 from the upper end of the fastener 5. At this time, the fastener 15 having a length of 13.5 mm and an outer diameter of 9.5 mm of the present invention has a caulking load 12 per piece of 650 kg.
f and a Vickers hardness of the same size as the present invention of 8
5 crimping load per uniform fastener 6
Was 700 kgf. Therefore, the fastener 15 of the present invention can set the crimping load 12 lower, and can prevent cracks or the like from entering the crimped portion. Thereby, mechanical reliability can be improved.

As a result, stress is applied in the axial direction 13 of the fastener 15. At this time, since the fastener 15 is formed of the low hardness portion 15a and the high hardness portion 15b, the low hardness portion 15a The stress is greater in the harder portion than in the portion 15b having higher hardness. Therefore, load 1
As the number 2 is increased, the plastic deformation starts in the lower hardness portion 15a before the higher hardness portion 15b.

That is, the lower hardness portion 15a expands outward by being restrained by the printed circuit board 4 on the upper portion and the lower hardness portion 15b to form the crimped portion 16.
Thereafter, when a desired crimped shape is obtained, the load 12 is taken. As a result, the fastener 15 is attached to the printed circuit board 4, and a large current circuit board is formed. Finally, FIG.
As shown in (1), the fastener 15, the electric component 14, and the bus bar 9 are screwed together with the screws 17 to complete the large current circuit board device.

When the diameter of the swaged portion was measured, the fastener 15 of the present invention was 12.7 mm,
Is 12.0 mm, and the fastener 15 of the present invention can form a larger diameter of the caulked portion, and the contact area with the printed circuit board 4 can be greatly improved. Thereby, electrical reliability can be improved.

Although the case where the fastener 15 is caulked in the through hole 5 provided in the printed circuit board 4 has been described here, the invention is not limited to this, and the fastener 15 may be caulked only to the bus bar 9. In addition, caulking may be performed on both the bus bar 9 and the printed circuit board 4. This may be performed by caulking two bus bars 9 and the printed circuit board 4, or individually connecting the bus bar 9 and the printed circuit board 4. You may be caulking.

FIG. 3 is a view in which the bus bar and the printed circuit board are individually caulked. In the figure, 16a is a first caulking portion, and 16b is a second caulking portion. As shown in the figure, the printed circuit board 4 has a flange portion 8 and a first caulking portion 16a, and the bus bar 9 has a first caulking portion 16a and a second caulking portion 16a.
Is caulked with the caulking portion 16b. At this time, the first caulking portion 16a is formed to have a lower hardness than the second caulking portion 16b, and the second caulking portion 16b is formed to have a lower hardness than the higher hardness portion 15b at the tip of the fastener 15. doing. In this way, caulking can be performed at two places at the same time, and a large current circuit board can be easily manufactured.

In addition to the above, the fastener 15 may be made of plastic or the like. Further, depending on how the electric component 14 is attached, a female screw for fixing the screw 17 may be provided inside the high hardness portion 15b of the fastener 15.

Embodiment 2 FIG. 4 is a sectional view showing a large current circuit board according to Embodiment 2 of the present invention. In the figure, reference numeral 14 denotes an electric component such as a semiconductor switching element;
Is a fastener which is a caulking member, 19 is a fastener 18
8 is a flange portion of the fastener 18, 9 is a bus bar formed of, for example, an elongated copper plate having a width of 12 mm and a thickness of 1.2 mm and capable of flowing a large current, 10 is a through hole provided in the bus bar 9, 4 is a printed board, 5 is a through-hole provided in the printed board 4, and 17 is a screw for fixing the bus bar 9 and the fastener 18 to the electric component 14.

FIG. 5 is a sectional view showing a fastener before caulking according to the second embodiment of the present invention. As shown in the figure, the fastener 18 is a cylindrical body having the same outer diameter except for the flange 8 at the tip. The tubular body has a two-stage plate thickness, and the plate thickness in the vicinity of the flange portion 8 is smaller than the plate thickness in the distant portion. Here, the portion near the flange portion 8 as the first body portion is a thin portion 18a,
Is referred to as a thick portion 18b. Furthermore,
The thin portion 18a has a lower hardness than the thick portion 18b. Numeral 12 denotes a crimping load when the fastener 15 is crimped, and numeral 13 denotes an axial direction of the fastener 15.

Next, a method of manufacturing the fastener 18 will be described. For example, the fasteners 18 are C1100, C1
A cylindrical body having a thin portion 18a and a thick portion 18b is formed by using copper, such as 220, C1201, or the like shown in JIS-H-3100 as a raw material, and working by grinding or cold heading (pressing). Thereafter, when annealing is performed on the whole, the thin portion 18a has a smaller heat capacity than the thick portion 18b, so that the temperature rises faster, and the progress speed of the annealing changes.
Therefore, the thin portion 18a is annealed earlier than the thick portion 18b, so that the thin portion 18a can be formed to have a lower hardness than the thick portion 18b.

When the copper is formed by cold heading, the shape of the fastener 18 is formed by tapping or stretching copper to cause plastic deformation. For this reason, the plastically deformed part of copper undergoes work hardening and becomes hard,
The crystal grains also become fine. Also, even if the copper processing is manufactured by grinding, if the processing speed is increased, the heat and physical impact generated at the time of processing causes copper to harden due to work hardening,
The crystal grains become fine.

This work hardening causes the hardened, fine crystal grains of copper to be subjected to an annealing treatment to remove internal strain during work hardening to cause recrystallization of copper and soften copper. Conditions for this annealing treatment vary depending on the degree of work hardening of the copper of the fastener 18. For example, when the fastener 18 is formed by cold forging from C1100 material, the temperature is 150 to 400 ° C., and the time is 30 minutes to 10 minutes.
Time is desirable.

In the case of the second embodiment, after the C1100 material is processed by cold heading, the thin portion 18a and the thick portion 18 are subjected to an annealing treatment at 200 ° C. for one hour.
A fastener 18 having hardness of about 85 and 125 in Vickers hardness was manufactured.

Next, a method of manufacturing a large current circuit board using the fastener 18 will be described. At this time, the fastener 15 has, for example, a length of 13.5 mm and an outer diameter of 9.5 m.
m, the outer diameter of the flange portion is 12 mm. First, as shown in FIG. 5, the fastener 18 is inserted into the through hole 5 provided in the printed circuit board 4. The size of the through hole 5 is larger than the outer diameter of the fastener 18 by about 0.1 mm to 0.5 mm.

Next, the fastener 1 is pressed using a hydraulic press or the like.
A load 12 is applied to the fastener 18 from the upper end of 8. At this time, the fastener 18 having a length of 13.5 mm and an outer diameter of 9.5 mm of the present invention has a caulking load 12 per piece of 550 kg.
f and a Vickers hardness of the same size as the present invention of 8
5 crimping load per uniform fastener 6
Was 700 kgf. Therefore, the fastener 18 of the present invention can set the crimping load 12 lower and can prevent cracks or the like from entering the crimped portion. Thereby, mechanical reliability can be improved.

As a result, stress is applied in the axial direction 13 of the fastener 18, and at this time, the stress is larger in the thin portion 18a than in the thick portion 18b. Therefore, load 1
2, the thinner portion 18a becomes thicker
Plastic deformation starts before b.

That is, the thin portion 18a is constrained by the thick portion 18b after caulking on the upper side and the printed board 4 below, and expands outward to form the caulked portion 19. Thereafter, when a desired crimped shape is obtained, the load 12 is removed, the fastener 15 is attached to the printed circuit board 4, and a large current circuit board is formed. Finally, as shown in FIG. 4, the fastener 18, the electric component 14, and the bus bar 9 are screwed using the screw 17 to complete the large current circuit board device.

When the diameter of the swaged portion was measured, the fastener 18 of the present invention was 13.5 mm, and the conventional fastener 6 was 63.5 mm.
Was 12.0 mm, and the fastener 18 of the present invention could form a larger diameter of the caulked portion, and could greatly improve the contact area with the printed circuit board 4. Thereby, electrical reliability can be improved.

Although the case where the fastener 18 is caulked in the through hole 5 provided in the printed circuit board 4 has been described here, the invention is not limited to this, and the fastener 15 may be caulked only to the bus bar 9. In addition, caulking may be performed on both the bus bar 9 and the printed circuit board 4. This may be performed by caulking two bus bars 9 and the printed circuit board 4, or individually connecting the bus bar 9 and the printed circuit board 4. You may be caulking.

In addition to the above, the fastener 18 may be made of plastic or the like. Further, a female screw for fixing the screw 17 may be provided inside the thick portion 18 b of the fastener 18 depending on how the electric component 14 is attached.

[0048]

As described above, according to the present invention, the hardness of the first body is lower than the hardness of the second body, so that the swaged portion is soft and easily deformed, and the load during swaging is reduced. It is small and can form a large swaged part,
This has the effect of significantly improving the reliability of the electrical connection.

Further, since the radial thickness of the first body is formed smaller than the radial thickness of the second body, the swaged portion is soft and easily deformed, and the load at the time of swage can be reduced. The caulked portion can be formed large, which has the effect of significantly improving the reliability of mechanical and electrical connections.

Also, the hardness of the first body is lower than the hardness of the second body, and the hardness of the first body is increased stepwise from the side closer to the flange. Two or more caulking objects can be caulked at a time with one caulking member, and a large current circuit board can be easily manufactured.

Further, the large current circuit board according to the present invention is provided with a caulking member as one or both of a printed board and a busbar for supplying a large current as a plate-shaped member. Can be firmly fixed, and a large-current circuit board with high mechanical and electrical connection reliability can be obtained.

Further, in the method for manufacturing a caulking member according to the present invention, a conductive metal is processed to form a cylindrical body having a uniform thickness and one end in the axial direction of the body radially outward from the body. Forming a flange portion protruding toward the first direction, and dividing the body portion into a first body portion close to the flange portion and a second body portion far from the flange portion, A step of performing only an annealing treatment to lower the hardness of the first body portion than the hardness of the second body portion, so that the crimping member can be easily processed and the manufacturing cost can be reduced. The swaged part is soft and easily deformed,
This has the effect of greatly improving the reliability of the electrical connection.

Further, by processing a conductive metal, a cylindrical body portion in which the radial thickness of the first body portion is smaller than the radial thickness of the second body portion and an axial direction of the body portion. A step of forming a flange portion protruding radially outward from the trunk at one end;
Annealing the entire body to reduce the hardness of the first body to lower than the hardness of the second body, so that the annealing can be easily performed and the load during crimping can be reduced. Is smaller and the swaged portion can be formed even larger, which has the effect of greatly improving the reliability of mechanical and electrical connections.

The step of forming a cylindrical body and a flange part protruding radially outward from the body at one axial end of the body by processing a conductive metal is a process of cold heading. In this case, the metal is hardened by work hardening and the crystal grains become finer, so that there is an effect that the metal can be easily softened by annealing.

The step of processing the conductive metal to form a cylindrical body and a flange part protruding radially outward from the body at one axial end of the body includes grinding. Since this is a process, the metal undergoes work hardening and becomes hard and the crystal grains become fine, so that there is an effect that the metal can be easily softened by annealing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a large current circuit board according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing the fastener before caulking according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating the high-current circuit board according to Embodiment 1 of the present invention;

FIG. 4 is a sectional view showing a large current circuit board according to Embodiment 2 of the present invention;

FIG. 5 is a sectional view showing a fastener before caulking according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a conventional large current circuit board.

FIG. 7 is a cross-sectional view showing a conventional fastener before caulking.

[Explanation of symbols]

4 printed circuit board, 8 flange, 9 bus bar, 1
5,18 fastener, 16,19 caulking part, 15a
High hardness part, 15b Low hardness part, 16a
First caulking portion, 16b Second caulking portion, 18a Thin portion, 18b Thick portion.

Claims (8)

[Claims] 1. A first body having a cylindrical body and a flange protruding radially outward from the body at one axial end of the body, wherein the body is close to the flange. And a second body portion remote from the flange portion, the first body portion is bent radially outward by applying pressure in the axial direction, and the bent first body portion and the second body portion are bent. A caulking member in which a plate-like member is pressed and held between the flange portion and the first body portion, wherein the hardness of the first body portion is lower than the hardness of the second body portion. 2. The caulking member according to claim 1, wherein a radial thickness of the first body is formed smaller than a radial thickness of the second body. 3. A first body having a cylindrical body and a flange protruding radially outward from the body at one axial end of the body, wherein the body is close to the flange. And a second body part remote from the flange part, two or more plate members are disposed on the first body part at a predetermined interval, and the first member is pressed in the axial direction. The two torso portions are bent outward in the radial direction by two or more, and one plate-shaped member is formed by the bent and deformed first body portion and the flange portion, and the other by the bent and deformed first body portions. Wherein the first body portion has a hardness lower than the hardness of the second body portion, and the first body portion has a hardness lower than the hardness of the first body portion. A crimping member characterized by gradually increasing hardness in a stepwise manner from a near side. 4. A large current having a caulking member according to claim 1, wherein the plate-shaped member is one or both of a printed circuit board and a bus bar for supplying a large current. Circuit board. 5. A conductive metal is processed to form a cylindrical body having a uniform thickness, and a flange part protruding radially outward from the body at one axial end of the body. And dividing the body into a first body close to the flange and a second body far from the flange, and performing an annealing process only on the first body to perform the first body. Making the hardness of the portion lower than the hardness of the second trunk portion. 6. A second body formed by processing a conductive metal and connecting to the first body and the first body and having a radial thickness greater than a radial thickness of the first body. Forming a cylindrical torso comprising a cylindrical portion and a flange portion protruding radially outward from the first torso at one axial end of the first torso; A step of performing an annealing treatment to lower the hardness of the first body portion than the hardness of the second body portion. 7. The step of processing a conductive metal to form a cylindrical body part and a flange part protruding radially outward from the body part at one axial end of the body part. The method for manufacturing a caulking member according to claim 5, wherein the method is a processing step. 8. The step of processing a conductive metal to form a cylindrical body and a flange portion at one axial end of the body that protrudes radially outward from the body. The method for manufacturing a caulking member according to claim 5, wherein the method is a step.