JPH0837202A - Metal post structure and method of mounting metal post - Google Patents

Abstract

PURPOSE:To improve defective bonding of a metal post and a wire by a method wherein the area of a soldering surface is set to be smaller than an upper surface area and the weight per unit area acting on solder paste is increased and the metal post is bitten into the solder paste in a good-balanced manner. CONSTITUTION:Solder paste 14 is printed in a pattern on a conductive pattern 13 and a recess part 11a is formed in a center part on a bottom surface of a metal post 11. When the such-structured metal post 11 is mounted to an electrode substrate 33, since the area of a bottom surface 11b of the metal post 11 is smaller than that of an upper surface 11c of the metal post 11, the weight of the metal post 11 acting per unit area in solder paste 14 is increased and the metal post 11 is bitten into the solder paste 14 in a good-balanced manner, and further when soldering, since reaction gas generated by chemical reaction can be collected in the recess part 11a, the metal post 11 can horizontally be collected to the electrode substrate 33. Thus, defective bonding of the wire and metal post 11 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal post structure and a method for mounting a metal post, and more particularly, it is used for connecting a substrate on which electronic parts and the like are mounted to an external electric substrate and is made of aluminum or the like. Metal post structure and mounting method of the metal post.

[0002]

2. Description of the Related Art In recent years, an air bag system has been mainly installed in combination with a seat belt as a safety measure in case of sudden braking due to an automobile accident. The accuracy of the operation of the sensor) and the transmission of the operation is required.

FIG. 7 shows a G sensor assembly in which a metal post such as aluminum is used to connect a board on which electronic parts such as a G sensor chip are mounted and an external electric board. In the figure, reference numeral 36 denotes a G sensor chip, and the G sensor chip 36 is a ceramic substrate (hereinafter,
It is mounted on a G sensor mounting substrate 12) and connects the G sensor mounting substrate 12 and a larger electrode substrate 33 with wires 32, or connects the electrode substrate 33 to an external electrode substrate (not shown). A metal post 31 is used when connecting with a terminal 32 for wiring with a wire 32.

As a method of mounting the metal post 31 on the electrode substrate 33, a pattern of solder paste is printed on the electrode substrate 33 and the metal post 31 is arranged thereon, and then the solder paste is melted in a high temperature atmosphere. There is a reflow soldering method. The reflow soldering method,
A brief description will be given with reference to FIGS.

First, the solder paste 14 is pattern-printed on the conductor pattern 13 on the electrode substrate 33 (a), and then the metal post 31 having a solder plated portion (not shown) is placed on the electrode substrate 33 with the solder plated portion facing down. It is carried and mounted on 14 parts of the above solder paste by a method such as air suction (b),
Next, for example, in an atmosphere of about 230 ° C, solder paste 1
Reflow soldering is performed by melting No. 4 (c). The metal post 31 has, for example, a diameter of about 1 mm and a height of about 0.4 to 0.5 mm, and has a columnar shape.

The wire 32 and the metal post 31 are joined by ultrasonically wire-bonding the upper surface of the reflow-soldered metal post 31.

9 and 10 show a state in which the metal post 31 is mounted on the electrode substrate 33, respectively.
Shows the case where it is correctly mounted, and FIG. 10 shows the case where it is mounted incorrectly.

When wire-bonding to the metal post 31 shown in FIG. 9, the wire 32 and the metal post 31 are easily joined correctly, but the metal post 3 shown in FIG.
In the case of wire bonding to No. 1, since the metal post 31 is inclined and the flatness on the metal post 31 cannot be ensured, the wire 32 and the metal post 31 are difficult to be joined correctly.

[0009]

In the metal post structure and the mounting method of the metal post 31, the metal post 31 is attached to the electrode substrate 33 by the generation of gas due to a chemical reaction during reflow soldering. It is difficult to install the metal post 31 horizontally, and the metal post 31 is likely to tilt, and it is likely that the flatness of the metal post upper surface 31a cannot be secured. As a result, there is a problem in that there is a high possibility that defective bonding will occur between the wire 32 and the metal post 31 during wire bonding.

As mentioned above, the airbag system is
Despite the frequency of whether or not it should operate once in a vehicle's life, it must operate reliably at that time, and conversely, when it should not operate (when there is no collision or airbags). (At the time of a minor collision that does not require deployment)
The equipment must have high reliability because it must not be activated. The operation of the G sensor in this airbag system is performed by the wire 32 and the metal post 31.
Improper transmission due to improper jointing with will lead to the occurrence of a life-threatening accident, which is extremely dangerous.

The present invention has been made in view of the above problems, and by securing the flatness of the upper surface of the soldered metal post, the defective connection between the metal post and the wire is improved, and safety measures are taken. It is an object of the present invention to provide a metal post structure and a metal post mounting method capable of improving reliability.

[0012]

In order to achieve the above object, the metal post structure according to the present invention is characterized in that the area of the soldering surface is set smaller than the area of the upper surface (1).

Further, the metal post structure according to the present invention is characterized in that, in the metal post structure described in the above (1), a recess is formed in the central portion of the bottom surface and the peripheral portion of the bottom surface is a soldering surface. (2).

Further, the metal post structure according to the present invention is characterized in that, in the metal post structure according to the above (2), a notch portion communicating with the recess is formed in the peripheral portion of the bottom portion (3). .

Further, the metal post structure according to the present invention is characterized in that, in the metal post structure according to the above (2), a gas vent hole communicating with the recess is formed in the peripheral portion of the bottom (4). .

The metal post structure according to the present invention is characterized in that, in the metal post structure described in (1) above, the soldering surface is formed radially from the center of the bottom surface.

The metal post mounting method according to the present invention is characterized in that a load is applied to the metal post during reflow soldering (6).

Further, in the method for mounting a metal post according to the present invention, a hole having an area smaller than the bottom area of the metal post is formed at a predetermined position of the wiring board on which the metal post is mounted, and the center of the hole is formed. And the center of the bottom surface of the metal post are aligned to solder the metal post to the wiring board (7).

The metal post mounting method according to the present invention uses the metal post according to any one of the above (1) to (5) when the metal post mounting method according to the above (6) is carried out. It is characterized by (8).

Further, the metal post mounting method according to the present invention uses the metal post according to any one of the above (1) to (4) when carrying out the metal post mounting method according to the above (7). It is characterized by (9).

[0021]

According to the metal post structure (1) having the above structure, since the area of the soldering surface is set smaller than the top surface area, the weight per unit area acting on the solder paste is increased and the metal posts are The metal post is well-balancedly incorporated into the solder paste, and the metal post is horizontally joined to the substrate. This improves the joint failure between the metal post and the wire during wire bonding, and improves the reliability of the joint portion.

Further, according to the metal post structure (2) having the above structure, since the concave portion is formed in the central portion of the bottom surface and the peripheral portion of the bottom surface serves as the soldering surface, per unit area which acts on the solder paste. And the reaction gas generated by the chemical reaction at the time of soldering is stored in the recess, and the metal post is bonded horizontally to the substrate, resulting in poor bonding between the metal post and the wire during wire bonding. Is improved and the reliability of the joint is improved.

Further, according to the metal post structure (3) having the above structure, since the notch portion communicating with the recess is formed in the peripheral portion of the bottom portion, the weight per unit area acting on the solder paste becomes large. , The reaction gas generated by the chemical reaction during soldering is stored in the recess, and the stored reaction gas is diffused from the notch, so that the metal post is bonded more horizontally to the substrate, and the wire bonding is performed. At this time, the defective connection between the metal post and the wire is further improved, and the reliability of the bonded portion is improved.

Further, according to the metal post structure (4) having the above-mentioned structure, since the gas vent hole communicating with the recess is formed in the peripheral portion of the bottom, the reaction gas contained in the recess is discharged from the gas vent hole. Since it is diffused, the same effect as in the case of (3) can be obtained.

Further, according to the metal post structure (5) having the above-described structure, since the soldering surface is formed radially from the center of the bottom surface, the weight per unit area acting on the solder paste becomes large, and Since the reaction gas generated by the chemical reaction at the time of soldering is easily diffused, the metal post is bonded horizontally to the substrate, and the bonding failure between the metal post and the wire at the time of wire bonding is improved, and the bonding is improved. The reliability of the part is improved.

Further, according to the metal post mounting method (6) having the above-described structure, a load is applied to the metal post during the soldering reflow, so that the reaction gas generated by the chemical reaction during the soldering causes the metal post. Is not lifted and tilted, and since the weight per unit area that acts on the solder paste is larger, the metal posts are bonded horizontally to the substrate, and the metal posts and wires are bonded during wire bonding. The defects are improved and the reliability of the joint is improved.

According to the metal post mounting method (7) having the above structure, a hole having an area smaller than the bottom area of the metal post is formed at a predetermined position of the wiring board on which the metal post is mounted. Since the center of the hole and the center of the bottom surface of the metal post are aligned and the metal post is soldered to the wiring board, the reaction gas, which is an instability factor, is diffused from the hole. The extra solder paste, which is an instability factor, flows into the holes, and moreover, the weight per unit area acting on the solder paste becomes large, so that the metal posts are joined horizontally to the substrate, which is a problem in wire bonding. The joint failure between the metal post and the wire is improved, and the joint reliability is improved.

According to the metal post mounting method (8) having the above structure, when the metal post mounting method of (6) is carried out, the metal post having any one of the structures (1) to (5) is mounted. Since it is used, a more remarkable effect can be obtained as compared with the case of (6).

Further, according to the metal post mounting method (9) having the above structure, when the metal post mounting method of (7) is carried out, the metal post having any one of the structures (1) to (4) is mounted. Since it is used, a more remarkable effect can be obtained as compared with the case of (7).

[0030]

Embodiments of the metal post structure and the method of mounting the metal post according to the present invention will be described below with reference to the drawings.
FIG. 1A is a perspective view of the metal post according to the first embodiment as viewed from the bottom side, and FIG. 1B is a view showing the mounting of the metal post on the electrode substrate. In the figure, 11 is a metal post, 33 is an electrode substrate, and 13 is a conductor pattern. The solder paste 1 is provided on the conductor pattern 13.
4 is pattern-printed, and a recess 11a is formed in the center of the bottom surface of the metal post 11.

When the metal post 11 having such a structure is mounted on the electrode substrate 33, the area of the bottom surface 11b of the metal post 11 is larger than that of the upper surface 11c of the metal post 11, as shown in FIG. Solder paste 14 because it is small
The weight of the metal post 11 acting per unit area becomes large, the metal post 11 bites into the solder paste 14 in a well-balanced manner, and at the time of soldering, the reaction gas generated by the chemical reaction can be collected in the recess 11a. Therefore, the metal post 11 can be horizontally joined to the electrode substrate 33. As a result, defective bonding between the wire and the metal post 11 during wire bonding is improved, and the reliability of the bonded portion can be improved.

FIG. 2A is a perspective view of the metal post according to the second embodiment as viewed from the bottom side, and FIG. 2B is a view showing the mounting of the metal post on the electrode substrate. In the figure, 15 is a metal post, 33 is an electrode substrate, and 13 is a conductor pattern. Solder paste 14 is printed on the conductor pattern 13, and a recess 15a is formed in the center of the bottom surface of the metal post 15. Has been formed. Further, a cutout portion 15d communicating with the recess 15a is formed at the bottom of the metal post 15.

When the metal post 15 having such a structure is mounted on the electrode substrate 33, the area of the bottom surface 15b of the metal post 15 is smaller than the area of the upper surface 15c of the metal post 15, as shown in FIG. 2B. Therefore, the weight of the metal post 15 acting per unit area of the solder paste 14 becomes large, the metal post 15 bites into the solder paste 14 in a well-balanced manner, and the reaction gas generated by a chemical reaction at the time of soldering is filled with the recess 15a. Since the collected reaction gas is diffused from the cutout portion 15d, the metal post 15 can be more horizontally joined to the electrode substrate 33. As a result, defective bonding between the wire and the metal post 15 during wire bonding is improved, and the reliability of the bonded portion can be improved.

FIG. 3A is a perspective view of the metal post according to the third embodiment as viewed from the bottom side, and FIG. 3B is a view showing the mounting of the metal post on the electrode substrate. In the figure, 16 is a metal post, 33 is an electrode substrate, and 13 is a conductor paste. A recess 16a is formed in the center of the bottom surface of the metal post 16. Also, the metal post 16
A gas vent hole 16d communicating with the recess 16a is formed at the bottom of the.

When the metal post 16 having such a structure is mounted on the electrode substrate 33, the area of the bottom surface 16b of the metal post 16 is smaller than the area of the upper surface 16c of the metal post 16, as shown in FIG. 3B. Therefore, the weight of the metal post 16 acting per unit area of the solder paste 14 becomes large, the metal post 16 bites into the solder paste 14 in a well-balanced manner, and the reaction gas generated by the chemical reaction during soldering is used to form the recess 16a. Since the collected reaction gas is diffused from the gas vent hole 16d, the metal post 16 can be joined more horizontally to the electrode substrate 33. As a result, defective bonding between the wire and the metal post 16 during wire bonding is improved, and the reliability of the bonded portion can be improved.

FIG. 4A is a perspective view of the metal post according to the fourth embodiment as viewed from the bottom side, and FIG. 4B is a view showing the mounting of the metal post on the electrode substrate. In the figure, 17 is a metal post, 33 is an electrode substrate, and 13 is a conductor pattern. A bottom surface 17b as a soldering surface is formed on the bottom surface of the metal post 17 in a radial shape, for example, like a cross. ing.

When the metal post 17 having such a structure is mounted on the electrode substrate 33, the area of the bottom surface 17b of the metal post 17 is smaller than the area of the upper surface 17c of the metal post 17, as shown in FIG. 4B. Since the shape of the bottom surface is radial, the weight of the metal post 17 acting per unit area of the solder paste 14 becomes large, and the metal post 1
Since 7 penetrates into the solder paste 14 in a well-balanced manner and the reaction gas generated by the chemical reaction at the time of soldering is easily diffused, the metal post can be joined to the electrode substrate 33 horizontally. As a result, the bonding failure between the metal post and the wire during wire bonding is improved,
The reliability of the joint can be improved.

FIG. 5 is a view showing a method of mounting a metal post according to the embodiment, in which 18 is a metal post, 33 is an electrode substrate, and 13 is a conductor paste.
Indicates a jig used to overload the metal post 18. The jig 19 is made of a material such as iron or stainless steel that can withstand the ambient temperature during reflow soldering.

When the metal post 18 is mounted by such a method, the metal post 1 is reflowed during soldering.
Since the load is applied to No. 8, the metal post 18 is prevented from being lifted and tilted by the reaction gas generated by the chemical reaction during soldering, and the weight of the metal post 18 acting per unit area of the solder paste 14 is reduced. Since it becomes larger, the metal post 18 can be joined horizontally to the electrode substrate 33. As a result, the bonding failure between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved. In addition,
Although the metal post 18 is used in the embodiment, the present invention is not limited to this, and the same effect can be obtained even with the conventional metal post 31 in other embodiments.

FIGS. 6A and 6B are views showing a mounting method of a metal post according to another embodiment, FIG. 6A shows a case where a conventional metal post 31 is mounted, and FIG. Shows the case where the metal post 11 according to the present invention is mounted. In the mounting method, the hole 20 having an area smaller than the bottom area of the metal post 31 (11) is formed at a predetermined position of the electrode substrate 33 and the conductor pattern 13 on which the metal post 31 (11) is mounted. Solder paste is printed on the surface excluding the holes 20, and the center of the holes 20 and the metal posts 31 (1
1) Match the bottom center of the metal post 31 (1)
1) is soldered to the electrode substrate 33. As a result, the reaction gas, which is an instability factor, is diffused from the hole 20, and the excess solder paste 14, which is an instability factor, flows into the hole 20, and the metal post 31 (11) is also removed. Since the contact area with the electrode substrate 33 is smaller than the upper area of the metal post 31 (11), the weight of the metal post 31 (11) acting per unit area of the solder paste 14 becomes large, and the metal post 31 (11 1
1) bites into the solder paste 14 in a well-balanced manner, and the metal posts 31 (11) can be joined horizontally to the electrode substrate 33. As a result, the bonding failure between the wire and the metal post 31 (11) during wire bonding is improved, and the reliability of the bonded portion can be improved.

Further, although the case where the metal post is mounted on the electrode substrate 33 is shown in this embodiment, the present invention is not limited to this, and the case where the metal post is mounted on another electrode substrate in another embodiment. May be

[0042]

As described above in detail, in the metal post structure (1) according to the present invention, the area of the soldering surface is set to be smaller than the upper surface area. Since the weight is increased, the metal post can be bitten into the solder paste in a well-balanced manner, and the metal post can be horizontally joined to the substrate. As a result, the bonding failure between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved.

Further, the metal post structure according to the present invention (2)
In, since the concave portion is formed in the central portion of the bottom surface and the peripheral portion of the bottom surface is the soldering surface, the weight per unit area acting on the solder paste is large, and
The reaction gas generated by the chemical reaction at the time of soldering is contained in the recess, and the metal post can be horizontally bonded to the substrate. As a result, the bonding failure between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved.

Further, the metal post structure according to the present invention (3)
In, since the notch portion communicating with the concave portion is formed in the peripheral portion of the bottom portion, the weight per unit area acting on the solder paste becomes large, and the reaction gas generated by the chemical reaction during soldering becomes the concave portion. In addition, since the reaction gas that has been stored in and is diffused from the cutout portion, the metal post can be bonded more horizontally to the substrate. As a result, the defective connection between the metal post and the wire during wire bonding is further improved, and the reliability of the bonded portion can be improved.

Further, the metal post structure according to the present invention (4)
In the above, since the gas vent hole communicating with the recess is formed in the peripheral portion of the bottom portion, the reaction gas accommodated in the recess is diffused from the gas vent hole, so that the same effect as in the case of (3) can be obtained. Obtainable.

Further, the metal post structure according to the present invention (5)
In the above, since the soldering surface is formed radially from the center of the bottom surface, the weight per unit area acting on the solder paste becomes large, and the reaction gas generated by the chemical reaction during soldering is diffused. Since the structure is easy, the metal post can be horizontally joined to the substrate. As a result, the bonding failure between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved.

According to the metal post mounting method (6) of the present invention, a load is applied to the metal post during reflow soldering, so that the reaction gas generated by the chemical reaction during soldering causes the metal Since the posts are not lifted and tilted and the weight per unit area acting on the solder paste is larger, the metal posts can be horizontally joined to the substrate. This allows
The poor bonding between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved.

Further, according to the metal post mounting method (7) of the present invention, a hole having an area smaller than the bottom area of the metal post is formed in a predetermined portion of the wiring board on which the metal post is mounted. , Because the center of the hole and the center of the bottom surface of the metal post are matched to solder the metal post to the wiring board, the reaction gas, which is an instability factor, is diffused from the hole, In addition, since excess solder paste, which is an instability factor, flows into the holes, and since the contact area of the metal post with the wiring board is smaller than the upper area of the metal post, the unit area of the solder paste is Since the weight of the metal post acting on is increased, the metal post can be horizontally joined to the electrode substrate. As a result, the bonding failure between the metal post and the wire during wire bonding is improved, and the reliability of the bonded portion can be improved.

According to the metal post mounting method (8) of the present invention, when the metal post mounting method according to (6) above is carried out, the structure according to any one of (1) to (5) above is used. Since the metal post of (6) is used, the effect described in (6) above can be made more remarkable.

According to the metal post mounting method (9) of the present invention, when the metal post mounting method described in (7) above is carried out, the structure according to any one of (1) to (4) above is used. Since the metal post of (1) is used, the effect described in (7) above can be made more remarkable.

[Brief description of drawings]

1A is a schematic perspective view showing a metal post structure according to a first embodiment, and FIG. 1B is a schematic sectional view showing a metal post structure according to the first embodiment.

2A is a schematic perspective view showing a metal post structure according to a second embodiment, and FIG. 2B is a schematic sectional view showing a metal post structure according to the second embodiment.

3A is a schematic perspective view showing a metal post structure according to a third embodiment, and FIG. 3B is a schematic sectional view showing a metal post structure according to the third embodiment.

4A is a schematic perspective view showing a metal post structure according to a fourth embodiment, and FIG. 4B is a schematic sectional view showing a metal post structure according to the fourth embodiment.

FIG. 5 is a schematic perspective view showing a mounting method of the metal post according to the embodiment.

6A and 6B are schematic cross-sectional views showing a mounting method of a metal post according to another embodiment.

FIG. 7 is a schematic perspective view showing a G sensor assembly in which a metal post is mounted.

FIG. 8 is a schematic cross-sectional view showing a conventional metal post mounting method.

FIG. 9 is a schematic perspective view showing how a metal post is accurately mounted on an electrode substrate.

FIG. 10 is a schematic perspective view showing how a metal post is incorrectly mounted on an electrode substrate.

[Explanation of symbols]

 11 Metal Post 11a Recess 11b Bottom 11c Upper 33 Electrode Substrate (Wiring Board) 13 Conductor Pattern 14 Solder Paste

Claims (9)

[Claims] 1. A metal post structure, wherein an area of a soldering surface is set smaller than an upper surface area. 2. The metal post structure according to claim 1, wherein a concave portion is formed at a central portion of the bottom surface and a peripheral portion of the bottom surface serves as a soldering surface. 3. The metal post structure according to claim 2, wherein a cutout portion communicating with the concave portion is formed in a peripheral portion of the bottom portion. 4. The metal post structure according to claim 2, wherein a gas vent hole communicating with the recess is formed in the peripheral portion of the bottom portion. 5. The metal post structure according to claim 1, wherein the soldering surface is formed radially from the center of the bottom surface. 6. A method of mounting a metal post, wherein a load is applied to the metal post during reflow soldering. 7. A hole having an area smaller than the bottom area of the metal post is formed at a predetermined location of a wiring board on which the metal post is mounted, and the center of the hole and the center of the bottom surface of the metal post are formed. A method of mounting a metal post, which comprises matching and soldering the metal post to the wiring board. 8. A method of mounting a metal post, wherein the metal post according to claim 1 is used when the method of mounting the metal post according to claim 6 is carried out. 9. A method for mounting a metal post, wherein the metal post according to any one of claims 1 to 4 is used when the method for mounting the metal post according to claim 7 is carried out.