JP2020107750A - Semiconductor device and alternator using the same - Google Patents

Abstract

To realize a semiconductor device capable of improving reliability, by reducing stress acting on a semiconductor chip when press fitting into an alternator.SOLUTION: A radiator 7, in which a fitting hole 16 is formed, is fixed, and a semiconductor device 6 is installed so that the pedestal part 2a side of a base 2 faces the mating hole 16. Top face of a press jig 8 is brought into contact with the bottom face of the base 2 so as to substantially matches a region 2d, and by pressing the bottom face of the base 2 in the direction of the radiator 7 by means of the press jig 8, the base 2 is fitted in the fitting hole 16 thus press-fitting the semiconductor device 6 to the radiator 7 of the alternator. External-diameter of the press jig 8 is between the diameter of the pedestal part 2a and the bore diameter of an outer peripheral protrusion 2b, similarly to the region 2d. Stress of a semiconductor chip is reduced by setting the external-diameter of a pressed-point for the bottom face of the base 2 of the semiconductor device 6 between the diameter of the pedestal part 2a and the bore diameter of the outer peripheral protrusion 2b.SELECTED DRAWING: Figure 2

Description

The present invention relates to a semiconductor device and an alternator using the same.

A semiconductor device used for rectifying an AC output of an alternator for an automobile includes a semiconductor chip, a base, a lead, and a conductive bonding material that bonds them.

As described in Patent Document 1, a semiconductor device has a structure in which a plurality of electronic components such as a transistor circuit chip and a capacitor are mounted.

When the semiconductor device is mounted on the alternator, the surface of the base that is not joined to the electronic component is pressed by a pressing jig and press-fitted into a fitting hole formed in the radiator of the alternator.

When the semiconductor device is press-fitted into the alternator, the base of the semiconductor device is deformed by the tightening force from the fitting hole and the pressing force of the pressing jig, which causes stress on the semiconductor chip.

Therefore, it is necessary to reduce stress on the semiconductor chip and improve reliability.

As a technique for providing a semiconductor device in which stress at the time of press-fitting is reduced to meet this demand, for example, a technique described in Patent Document 2 is known.

Patent Document 2 describes a technique in which a bottom surface of a base of a semiconductor device is formed into a curved shape to relieve stress during press fitting.

JP, 2017-98276, A JP 2004-296595 A

In recent years, the mounting amount of electronic components in semiconductor devices tends to increase, and it is necessary to increase the area in order to secure the mounting amount. Therefore, it is conceivable to thin the base of the semiconductor device in order to increase the mounting area of the semiconductor device in the height direction.

When the base of a semiconductor device is thinned to secure a mounting area for electronic components, the bending rigidity of the base is reduced.

Therefore, the base is likely to be bent and deformed by the influence of the tightening force from the fitting hole of the alternator, and the peculiar bending and deformation is generated on the bottom surface side of the base.

Therefore, when thinning the base of the semiconductor device, it is necessary to suppress the bending deformation of the base in order to reduce the stress of the semiconductor chip and improve the reliability.

The present invention has been made in view of the above problems, and realizes a semiconductor device in which stress acting on a semiconductor chip during press-fitting into an alternator is reduced and reliability can be improved, and an alternator using the same. Is.

The present invention is configured as follows to solve the above problems.

A semiconductor device includes a lead electrode, an electronic component connected to the lead electrode, and a base that supports the electronic component. The base has the electronic component disposed on one surface of the base. A pedestal portion and an annular outer circumferential convex portion arranged on the outer circumferential side of the pedestal portion are formed, and the semiconductor device is provided in a hole of an external member on a bottom surface which is a surface opposite to one surface of the base. A jig contact area is formed in contact with the pressing jig for insertion.

Further, in an alternator including a rotor, a stator, and a rectifier, the rectifier has a semiconductor device inserted into a fitting hole formed in a radiator, and the semiconductor device has a lead electrode and the lead electrode. And an electronic component connected to the base, and a base that supports the electronic component, the base is on one surface of the base, a pedestal portion on which the electronic component is disposed, and an outer peripheral side of the pedestal portion. A circular ring-shaped outer peripheral convex portion is formed and a pressing jig for inserting the semiconductor device into a hole of an external member comes into contact with a bottom surface that is a surface opposite to one surface of the base. A tool contact area is formed.

According to the present invention, it is possible to realize a semiconductor device that can reduce the stress acting on a semiconductor chip at the time of press fitting into an alternator and improve reliability, and an alternator using the same.

It is a schematic sectional drawing of the semiconductor device 6 which concerns on 1st Example. It is a schematic sectional drawing which shows the state which presses the semiconductor device which concerns on 1st Example into the fitting hole formed in the radiator of the alternator. It is a figure which is an example different from this invention, and shows an example for comparing with this invention. 7 is a graph showing a result of measuring strain when a semiconductor device is press-fitted into a fitting hole by a method according to a comparative example. It is a schematic diagram of the direction of bending deformation of the base considered from the measurement result of the comparative example shown in FIG. It is a figure which shows a stress analysis model. It is a figure which shows the press location in each condition of stress analysis. It is a figure which shows the semiconductor chip stress of each condition obtained as a result of stress analysis. It is a figure which shows the bending deformation amount of each condition obtained as a result of stress analysis. It is a figure which shows the press location in each condition of stress analysis. It is a figure which shows the semiconductor chip stress of each condition obtained as a result of stress analysis. It is a schematic sectional drawing of the semiconductor device which concerns on 2nd Example. It is a schematic sectional drawing of the semiconductor device and pressing jig which concern on 3rd Example. It is a schematic sectional drawing of the semiconductor device which concerns on 4th Example of this invention. It is a schematic sectional drawing of the alternator which has a rectifier with which any one of the semiconductor devices of a 1st example-a 4th example was press-fitted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the embodiments described here, and various combinations and improvements can be made without departing from the scope of the invention.

(First embodiment)
FIG. 1 is a schematic sectional view of a semiconductor device 6 according to the first embodiment of the present invention.

In FIG. 1, a semiconductor device 6 is an electronic component including a semiconductor chip 1a, a capacitor 1b, a control circuit chip 1c, a source frame 1d, an electronic component conductive bonding material 1e, a wire 1f, a lead frame 1g, and an electronic component resin 1h. 1, a base 2 on which the electronic component 1 is arranged, a lead electrode 3, a conductive bonding material 4 for a semiconductor device, and a resin 5 for a semiconductor device. The electronic component 1 is connected to the lead electrode 3.

The base 2 is a member that supports the electronic component 1, and is a circular pedestal portion 2a on which the electronic component 1 is arranged by being joined to the electronic component 1 via the conductive bonding material 4 for a semiconductor device, and the pedestal portion 2a. It has a ring-shaped outer peripheral convex portion 2b arranged on the outer peripheral side and provided so as to surround the pedestal portion 2a, and a base portion 2c. An annular groove is formed between the pedestal portion 2a and the outer peripheral protrusion 2b.

The circular pedestal portion 2 a and the annular outer peripheral convex portion 2 b are formed on one surface of the base 2.

As a material of the source frame 1d, the base 2, the lead frame 1g, and the lead electrode 3, copper or copper alloy having excellent electrical conductivity and thermal conductivity is desirable. In particular, since the base 2 receives a tightening force and a pressing force at the time of press fitting, a high-strength material such as an alloy of zirconium and copper is preferable.

The thickness of the base 2 is about 3 to 4 mm.

When the semiconductor device 6 is mounted on the alternator, the surface of the base portion 2c opposite to the surface on which the pedestal portion 2a is located (one surface of the base 2) is pressed from the outside by a pressing jig, so that It is inserted (press-fitted) into the fitting hole formed in the radiator. At this time, on the bottom surface of the base 2 (the surface on which the pedestal portion 2a is arranged, that is, the surface opposite to one surface of the base 2), there are an area 2d contacting the pressing jig and an area 2e not contacting the pressing jig. The greatest feature of the configuration of the first embodiment is that the outer diameter of the area 2d that is set and is in contact with the pressing jig is not less than the diameter of the pedestal portion 2a and not more than the inner diameter of the outer peripheral protrusion 2b.

FIG. 2 is a schematic sectional view showing a state in which the semiconductor device 6 according to the first embodiment is press-fitted into the fitting hole 16 formed in the radiator 7 of the alternator.

In FIG. 2, when the semiconductor device 6 is press-fitted into the fitting hole 16 of the radiator (external member) 7 of the alternator, the radiator 7 having the fitting hole 16 is fixed, and the base 2 a of the base 2 is provided. The semiconductor device 6 is installed so that its side faces the fitting hole 16.

The top surface of the pressing jig 8 (the surface that presses the bottom surface of the base 2) is brought into contact with the bottom surface of the base 2 so as to substantially coincide with the region 2d. Then, the base 2 is fitted into the fitting hole 16 by pressing the bottom surface of the base 2 toward the radiator 7 by the pressing jig 8.

The outer diameter of the pressing jig 8 is equal to or larger than the diameter of the pedestal portion 2a and equal to or smaller than the inner diameter of the outer peripheral protrusion 2b, similarly to the region 2d. An area 2d on the bottom surface of the base 2 where the pressing jig 8 contacts the bottom surface of the base 2 is defined as a jig contact area.

In the first embodiment, a region 2d where the pressing jig 8 contacts the bottom surface of the base 2 is formed as a jig contact region.

FIG. 3 is a diagram showing an example different from the present invention, which is an example for comparison with the present invention. In the example shown in FIG. 3, the jig contact area is any area on the entire bottom surface of the base 2, and is not specified as in the first embodiment of the present invention.

Further, in the example shown in FIG. 3, the outer diameter of the annular pressing jig 8 is larger than the inner diameter of the outer peripheral protrusion 2b.

In the example shown in FIG. 3, the bottom surface of the base 2 is pressed only by the annular portion of the annular pressing jig 8 to press the semiconductor device 6 into the fitting hole of the radiator 7.

FIG. 4 shows the result of measuring the strain at the center of the pedestal portion 2a of the base 2 and the bottom surface of the base 2 when the semiconductor device 6 is press-fitted into the fitting hole of the radiator 7 by the method according to the comparative example shown in FIG. It is a graph. Further, FIG. 5 is a schematic diagram of the bending deformation direction of the base 2 which is considered from the measurement result of the comparative example shown in FIG.

4 and 5, during the press-fitting, a compressive strain acts on the pedestal portion 2a of the base 2 and a tensile strain acts on the bottom face of the base. Therefore, the base 2 has a convex bending deformation on the bottom surface side of the base.

During the press-fitting, only the pedestal portion 2a side of the base receives the tightening force from the radiator 7. It is considered that this tightening force caused bending deformation.

In order to evaluate the stress acting on the semiconductor chip 1a due to the bending deformation of the base 2 during the press fitting, the stress analysis by the finite element method was performed.

FIG. 6 is a diagram showing a stress analysis model. The example shown in FIG. 6 is a two-dimensional axisymmetric model in consideration of the symmetry of the shape of the base 2. Further, in order to severely evaluate the influence of the deformation of the base 2 on the semiconductor chip 1a, only the semiconductor chip 1a, the electronic component conductive bonding material 1e, and the base 2 were modeled as members. A press-fitting process was simulated by applying a tightening force F corresponding to the tightening from the inner wall of the fitting hole to only the half of the side surface of the base on the pedestal portion 2a side.

The pressing force P from the pressing jig was applied to the bottom surface of the base 2. The first embodiment of the present invention and the comparative example shown in FIG. 3 were compared by changing the location where the pressing force P is applied. The load of the pressing force P under each condition of changing the pressed portion is the same.

FIG. 7 is a diagram showing pressed portions under each condition of stress analysis. In FIG. 7, the pressed portion was under three conditions of A, B, and C. The condition A is a condition in which the outer diameter of the pressed portion exceeds the inner diameter of the outer peripheral convex portion 2b, and corresponds to the comparative example shown in FIG.

The condition B is a condition that the outer diameter of the pressed portion is equal to or larger than the diameter of the pedestal portion 2a and equal to or smaller than the inner diameter of the outer peripheral protrusion 2b, and is included in the first embodiment of the present invention.

Condition C is a condition in which the outer diameter of the pressed portion is smaller than the diameter of the pedestal portion 2a, and is an additional comparative example simulating a case where a concentrated pressing force is applied to the center of the base (separate from the example shown in FIG. 3). Is a comparative example).

FIG. 8 is a diagram showing the semiconductor chip stress under each condition obtained as a result of the stress analysis. Relative comparison was performed by setting the stress of condition A, which is the comparative example shown in FIG. 3, to 1.

In FIG. 8, under the condition C, a stress 7 times that under the condition A is generated, but under the condition B included in the first embodiment, the stress is reduced to 0.2 times under the condition A. In order to show the reason, the bending deformation amounts of the analytical models under each condition were compared.

FIG. 9 is a diagram showing the bending deformation amount under each condition obtained as a result of the stress analysis. In FIG. 9, the amount of deformation under condition A was set to 1, and relative comparison was performed. Under the condition A, since the outer peripheral portion of the base 2 is pressed, as shown in FIGS. 4 and 5, the clamping force from the inner wall of the fitting hole 16 causes a convex bending deformation on the bottom surface side of the base 2. ..

Under the condition B, the pressing force acts in the direction of canceling the convex bending deformation on the bottom surface side of the base, so that the bending deformation amount of the base 2 is reduced. As a result, it is considered that the stress on the semiconductor chip was also reduced.

Under the condition C, the pressing force acts in the direction of canceling the convex bending deformation on the base bottom surface side, but since the pressing force is concentrated on the center part of the base, the convex bending deformation occurs excessively on the pedestal side, As a result, it is considered that the semiconductor chip stress also increased.

From the above, it is effective for reducing the chip stress that the pressing force acts on the bottom surface side of the base 2 in the direction of canceling the convex bending deformation and the pressing force is not concentrated too much in the center of the base 2. I know there is.

Further stress analysis was carried out to show the range of pressed points where the stress reduction effect can be obtained. FIG. 10 is a diagram showing pressed portions under each condition of stress analysis. In FIG. 10, two conditions, D and E, were added as pressing points. Both conditions D and E are included in the first embodiment.

The condition D has a portion having the same pressing portion as the condition B, but the pressing range is increased as compared with the condition B. The condition E is to expand the range of the pressed portion more than the condition D and press the entire range having the same diameter as the pedestal portion 2a.

FIG. 11 is a diagram showing the semiconductor chip stress under each condition obtained as a result of the stress analysis. In FIG. 11, the condition D is 0.2 times the condition A, which is equivalent to the condition B, and the condition E is 0.4 times the stress of the condition A. In either condition, the comparative example shown in FIG. It is understood that the stress reducing effect can be obtained under the condition A of 1.

From the above, as in the first embodiment of the present invention, the outer diameter of the pressing portion (jig contact region 2d) with respect to the bottom surface of the base 2 of the semiconductor device 6 is equal to or larger than the diameter of the pedestal portion 2a and the outer peripheral convex portion 2b. It can be seen that the stress of the semiconductor chip can be reduced by setting the inner diameter to be less than or equal to

Further, it can be seen that the stress can be further reduced by pressing the annular area excluding the center of the base 2 as in the conditions B and D.

That is, according to the first embodiment of the present invention, a jig for pressing the bottom surface of the base 2 of the semiconductor device 6 by the pressing jig 8 is not less than the diameter of the pedestal portion 2a and not more than the inner diameter of the outer peripheral protrusion 2b. Since the contact region 2d is formed, the stress acting on the semiconductor chip at the time of press-fitting into the alternator is reduced, and a semiconductor device capable of improving reliability can be realized.

In addition, as described above, the outer diameter of the pressing jig 8 needs to be equal to or larger than the diameter of the pedestal portion 2a and smaller than or equal to the inner diameter of the outer peripheral protrusion 2b.

(Second embodiment)
FIG. 12 is a schematic sectional view of a semiconductor device 6 according to the second embodiment of the present invention.

In FIG. 12, the second embodiment has a bottom surface protrusion 2f on the bottom surface of the base 2. The diameter of the bottom surface convex portion 2f is equal to or larger than the diameter of the pedestal portion 2a and equal to or smaller than the inner diameter of the outer peripheral convex portion 2b, similarly to the jig contact area 2d of the first embodiment. Therefore, the bottom surface convex portion 2f becomes the jig contact area. The diameter of the pressing jig 8 is set to be equal to or larger than the diameter of the bottom surface protrusion 2f.

In the semiconductor device of the second embodiment, the area in contact with the pressing jig 8 is the bottom surface convex portion 2f, and the diameter thereof is equal to or larger than the diameter of the pedestal portion 2a and equal to or smaller than the inner diameter of the outer peripheral convex portion 2b. It is possible to obtain a semiconductor device in which a stress reducing effect similar to that can be obtained, the stress acting on the semiconductor chip at the time of press-fitting into the alternator is reduced, and the reliability can be improved.

Further, if the diameter of the pressing jig 8 is equal to or larger than the diameter of the bottom surface convex portion 2f, there is an advantage that the same effect can be obtained even if the dimensions are different.

(Third embodiment)
FIG. 13 is a schematic sectional view of the semiconductor device 6 and the pressing jig 8 according to the third embodiment of the present invention.

In the third embodiment, the pressing jig 8 has a ring-shaped pressing jig convex portion 8a on the surface in contact with the bottom surface of the base 2 of the semiconductor device 6. The outer diameter of the annular pressing jig convex portion 8a is not less than the diameter of the pedestal portion 2a and not more than the inner diameter of the outer peripheral convex portion 2b.

On the bottom surface of the base 2 of the semiconductor device 6, there is formed an annular jig contact region whose outer diameter is greater than or equal to the diameter of the pedestal portion 2a and less than or equal to the inner diameter of the outer peripheral protrusion 2b.

According to the third embodiment, the same effect as that of the first embodiment can be obtained, and the stress reduction effect can be further obtained because the conditions are the annular ranges like the conditions B and D shown in FIGS. There is an effect that is.

The inner diameter of the annular jig contact area can be set arbitrarily, but may be about half the outer diameter of the annular jig contact area, for example.

(Fourth embodiment)
FIG. 14 is a schematic sectional view of a semiconductor device 6 according to the fourth embodiment of the present invention.

In the fourth embodiment of the present invention, an annular bottom surface protrusion 2g is formed on the bottom surface of the base 2.

The outer diameter of the annular bottom convex portion 2g is not less than the diameter of the pedestal portion 2a and not more than the inner diameter of the outer circumferential convex portion 2b. The annular bottom convex portion 2g corresponds to an annular jig contact area. The pressing jig 8 is the same as in the first and second embodiments, and the outer diameter thereof is equal to or larger than the outer diameter of the annular bottom surface convex portion 2g.

Since the pressed portion on the bottom surface of the semiconductor device 6 in the fourth embodiment is the same as the pressed portion in the third embodiment, a similar stress reducing effect can be obtained. The pressing jig 8 has an advantage that the same effect can be obtained even if the dimensions are different as long as the outer diameter is equal to or larger than the diameter of the annular bottom surface convex portion 2g.

In addition, the annular bottom convex portion 2g is similar to the second embodiment in that the pressing jig 8 does not come into contact with the bottom surface of the base 2 when the annular bottom convex portion 2g is pressed by the pressing jig 8. It suffices that it projects from the bottom surface of the base 2. For example, the protrusion may be about 1 mm.

The inner diameter of the ring-shaped bottom convex portion 2g can be set arbitrarily, but may be, for example, about half the outer diameter of the circular ring-shaped bottom convex portion 2g.

(Fifth embodiment)
Although the first to fourth embodiments described above are examples of the semiconductor device 6, the alternator having the semiconductor device according to the first to fourth embodiments is also realized as an embodiment of the present invention.

Here, a schematic configuration of the alternator will be described.

FIG. 15 is a schematic sectional view of an alternator 15 having a rectifier into which any one of the semiconductor devices 6 of the first to fourth embodiments of the present invention is press fitted.

In FIG. 15, the alternator 15 includes a rectifier 9 into which a semiconductor device is press-fitted, a rotor 10, a stator 11, a shaft 14, and a housing 13. The rectifier 9, the rotor 10, the stator 11, and the shaft 14 are arranged inside the housing 13. A bearing 12 that rotatably supports the shaft 14 is formed in the housing 13.

The semiconductor device 6 is inserted into a fitting hole 16 formed in the radiator 7 of the rectifier 9 to form an electric circuit, and converts the alternating current generated by the stator 11 into direct current.

As described above, in the semiconductor device 6 according to the first to fourth embodiments of the present invention, the stress acting on the semiconductor chip at the time of press-fitting into the alternator is reduced, and the reliability can be improved. The alternator including the rectifier 9 into which the semiconductor device 6 of any of the first to fourth embodiments is press-fitted can also improve reliability.

It should be noted that the present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.

Further, it is possible to add, delete, or replace a part of the configuration of each embodiment without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1... Electronic component, 1a... Semiconductor chip, 1b... Capacitor, 1c... Control circuit chip, 1d... Source frame, 1e... Electronic component conductive bonding material, 1f... -Wire, 1g... Lead frame, 1h... Resin for electronic parts, 2... Base, 2a... Pedestal part, 2b... Outer peripheral convex part, 2c... Base part, 2d... Area contacting the pressing jig, 2e... Area not contacting the pressing jig, 2f... Bottom convex portion, 2g... Annular bottom convex portion, 3... Lead electrode, 4... Conductivity for semiconductor device Bonding material, 5... Resin for semiconductor device, 6... Semiconductor device, 7... Radiator, 8... Pressing jig, 8a... Torus pressing jig convex portion, 9... Rectifier , 10... Rotor, 11... Stator, 12... Bearing, 13... Housing, 14... Shaft, 15... Alternator, 16... Fitting hole

Claims (10)

A lead electrode,
An electronic component connected to the lead electrode,
A base supporting the electronic component,
The base has, on one surface of the base, a pedestal portion on which the electronic component is arranged, and an annular outer peripheral convex portion arranged on an outer peripheral side of the pedestal portion, and the one surface of the base is formed. A semiconductor device, wherein a jig contact region, which is in contact with a pressing jig for inserting the semiconductor device into a hole of an external member, is formed on a bottom surface that is a surface opposite to the semiconductor device. The semiconductor device according to claim 1,
An outer diameter of the jig contact region is equal to or larger than a diameter of the pedestal portion and is equal to or smaller than an inner diameter of the outer peripheral convex portion. The semiconductor device according to claim 2,
The semiconductor device, wherein the jig contact area is a bottom surface convex portion formed on the bottom surface. The semiconductor device according to claim 2,
The semiconductor device, wherein the jig contact region has an annular shape. The semiconductor device according to claim 2,
The semiconductor device, wherein the jig contact region is an annular bottom convex portion. In an alternator including a rotor, a stator, and a rectifier,
The rectifier has a semiconductor device inserted into a fitting hole formed in a radiator, and the semiconductor device has a lead electrode, an electronic component connected to the lead electrode, and a base that supports the electronic component. And the base has, on one surface of the base, a pedestal on which the electronic component is disposed, and an annular outer peripheral protrusion disposed on the outer peripheral side of the pedestal, the An alternator characterized in that a jig contact region, which is in contact with a pressing jig for inserting the semiconductor device into a hole of an external member, is formed on a bottom surface which is a surface opposite to one surface of a base. The alternator according to claim 6,
An outer diameter of the jig contact region of the semiconductor device is equal to or larger than a diameter of the pedestal portion and smaller than or equal to an inner diameter of the outer peripheral protrusion portion. The alternator according to claim 7,
The alternator, wherein the jig contact area of the semiconductor is a bottom surface convex portion formed on the bottom surface. The alternator according to claim 7,
The alternator, wherein the jig contact region of the semiconductor has an annular shape. The alternator according to claim 7,
The alternator, wherein the jig contact region of the semiconductor is an annular bottom convex portion.

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