JP2020088274A - Semiconductor unit, electronic device, and semiconductor unit manufacturing method - Google Patents

Abstract

To provide a semiconductor unit that can improve the stress absorption performance of a solder connection portion, an electronic device, and a semiconductor unit manufacturing method.SOLUTION: An insulating member 4 is arranged between a wiring board 2 and a semiconductor element 3, and a solder connection portion 51 passing through a through hole 41 of the insulating member 4 constitutes an electric connecting portion 5. Since the solder connection portion 51 passes through the through hole 41 of the insulating member 4, a molten solder metal is held by the through hole 41 in a soldering process and is unlikely to hang down due to its own weight. Therefore, by a Z-direction dimension of the insulating member 4 is appropriately set, and therefore, the Z-direction dimension of the solder connection portion 51 can be increased and the stress absorption performance can be improved.SELECTED DRAWING: Figure 1

Description

The present invention relates to a semiconductor unit, an electronic device and a semiconductor unit manufacturing method.

In general, a semiconductor unit in which a semiconductor element is mounted on a wiring board is known in which electrodes of the semiconductor element and electrodes of the wiring board are electrically connected by soldering. In such a semiconductor unit, the linear expansion coefficient of the wiring board and the linear expansion coefficient of the semiconductor element may be different, and when they are placed under high temperature or the temperature rises due to use, due to the difference in linear expansion coefficient, Stress may be applied to the solder metal.

Therefore, in order to absorb the stress caused by the difference in linear expansion coefficient, a connection structure has been proposed in which a metal wiring (electrode) is projected from a substrate (wiring board) and a solder ball is provided at the tip of this metal wiring ( For example, see Patent Document 1). In the connection structure described in Patent Document 1, the deformation of the metal wiring makes it possible to absorb the stress caused by the difference in linear expansion coefficient.

However, in the configuration in which the metal wiring is deformed as described in Patent Document 1, the stress may not be completely absorbed when the difference in linear expansion coefficient becomes large, and it is desired to further improve the stress absorption performance. It was rare. Therefore, it is conceivable to increase the size of the solder connection portion in the direction in which the wiring board and the semiconductor element face each other. However, when soldering while making the facing direction and the vertical direction substantially coincident with each other, the facing direction dimension of the solder connection part has an upper limit due to the relationship between the weight of the solder metal and the surface tension between the solder metal and the electrode. It will be decided. Therefore, it is difficult to improve the stress absorption performance by increasing the size of the solder connection portion in the facing direction.

An object of the present invention is to provide a semiconductor unit, an electronic device, and a semiconductor unit manufacturing method capable of improving the stress absorption performance of a solder joint.

The invention according to claim 1 includes a wiring board, a semiconductor element arranged so as to overlap with the wiring board, and an electrical connecting portion that connects an electrode of the wiring board and an electrode of the semiconductor element. The unit further includes an insulating member arranged between the wiring board and the semiconductor element, and the insulating member extends along a facing direction of the wiring board and the semiconductor element. In the semiconductor unit, a plurality of through holes are formed, and the electrical connection portion is configured to have a solder connection portion that passes through each of the plurality of through holes.

According to the semiconductor unit of the present invention, since the solder connection portion passes through the through hole of the insulating member, the molten solder metal is held by the through hole during the soldering process and is unlikely to sag due to its own weight. Therefore, by appropriately setting the facing dimension of the insulating member, the facing dimension of the solder connection portion can be increased, and the stress absorption performance can be improved.

It is a sectional view showing a semiconductor unit concerning a 1st embodiment of the present invention. It is a top view which shows the upper surface of the wiring board of the said semiconductor unit. It is a top view showing the lower surface of the semiconductor element of the semiconductor unit. 6 is a graph showing a relationship between an electrode of the wiring board and a linear expansion coefficient of an insulating member in the semiconductor unit. It is sectional drawing which shows the semiconductor unit which concerns on 2nd Embodiment of this invention. It is a graph which shows the conditions of Examples 1-11 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the second embodiment, the same components as those described in the first embodiment and components having the same function are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

[First Embodiment]
As shown in FIG. 1, the semiconductor unit 1A of the present embodiment includes a wiring board 2, a semiconductor element 3, an insulating member 4, and an electrical connection portion 5. In the following, the two directions along the surface of wiring board 2 and substantially orthogonal to each other will be referred to as the X direction and the Y direction, and the plate thickness direction (perpendicular direction) of wiring board 2 will be the Z direction. In addition, the Z direction is substantially the same as the vertical direction unless otherwise specified.

The wiring board 2 is a mounting substrate on which the semiconductor element 3 is mounted, and has a plurality of electrodes 22 provided on the upper surface 21 side as shown in FIG. The wiring board 2 is made of, for example, glass epoxy having a thickness of about 1 mm as a base material. Although only one semiconductor element 3 is shown in FIG. 1, a plurality of semiconductor elements may be mounted on the wiring board 2.

The entire semiconductor element 3 is formed in a plate shape extending along the XY plane, and is arranged so as to overlap with the upper surface 21 side of the wiring board 2 with the Z direction as the opposite direction. The semiconductor element 3 includes, for example, a rewiring layer 31 made of glass epoxy as a base material, a silicon chip 32 die-bonded to an upper surface side of the rewiring layer 31 (that is, a side opposite to the wiring board 2), and a chip. And a protective layer 33 made of epoxy that covers 32 from the upper surface side.

In the semiconductor element 3, as shown in FIG. 3, a plurality of electrodes 34 are provided on the lower surface 311 side of the redistribution layer 31. The plurality of electrodes 34 of the semiconductor element 3 are arranged corresponding to the plurality of electrodes 22 of the wiring board 2, and specifically, are arranged so as to face each other in the Z direction. The semiconductor element is not limited to the one having the electrode provided on the lower surface side, and may have the electrode protruding from the side surface thereof.

The electrode 22 of the wiring board 2 and the electrode 34 of the semiconductor element 3 are both circular, and the diameters of the corresponding electrodes 22 and 34 are approximately the same. The electrode 22 of the wiring board 2 and the electrode 34 of the semiconductor element 3 have a larger diameter as they are located farther from the central portion O in the XY plane. The direction in which each of the electrodes 22 and 34 extends from the central portion O toward its center is the deformation direction. That is, the dimension of the electrodes 22, 34 in the deformation direction is equal to the diameter.

At this time, it is preferable that the diameters of the electrodes 22 and 34 increase in three or more steps as the distance from the central portion O increases. Further, the adjacent electrodes 22 and 34 are arranged with a predetermined space therebetween. Therefore, the density of the electrodes 22 and 34 is higher in the region closer to the central portion O.

The central portion O is a position (deformation reference position) that becomes a center when the semiconductor element 3 is thermally deformed, and, for example, when the semiconductor element 3 has a disk shape, it may be a center of the circle. Well, in the case of a rectangular shape, it may be the intersection of diagonal lines, and in the case of other shapes, it may be the center of gravity.

The insulating member 4 is formed into a plate shape that extends along the XY plane, and is arranged so as to be sandwiched between the wiring board 2 and the semiconductor element 3 in the Z direction. The insulating member 4 is provided with a plurality of through holes 41 extending along the Z direction. The number of through holes 41 is the same as the number of electrodes 22 of wiring board 2 and electrodes 34 of semiconductor element 3.

The positions of the through holes 41 correspond to the electrodes 22 of the wiring board 2 and the electrodes 34 of the semiconductor element 3, respectively. The through hole 41 is assumed to be formed in a cylindrical shape, for example. Although the diameters of the plurality of through holes 41 are equal to each other, the diameter may be increased as the electrodes 22 and 34 are located farther from the central portion O in the XY plane.

The insulating member 4 is not directly fixed to the wiring board 2 or the semiconductor element 3, but may be fixed to the wiring board 2 or the semiconductor element 3.

The electrical connection portion 5 is for electrically connecting the electrode 22 of the wiring board 2 and the electrode 34 of the semiconductor element 3 and is composed of a plurality of solder connection portions 51. The solder connection portion 51 is configured to pass through each of the plurality of through holes 41. That is, the solder connection portion 51 is formed by melting the solder metal and filling the through hole 41, and the solder connection portion 51 has a cylindrical shape.

The method of filling the through hole 41 with the solder metal is arbitrary. For example, the rod-shaped solder metal may be inserted into the through hole 41 in advance and the solder metal may be melted. It may be supplied in 41.

Further, regarding the electrode 22 and the solder connection portion 51 of the wiring board 2 which correspond to each other, the linear expansion coefficient of the insulating member 4 is α1, the linear expansion coefficient of the wiring board 2 is α2, and the joining temperature of the solder connection portion 51 is T When the reference room temperature is Tr, the distance between the center portion O on the XY plane and the solder connection portion 51 is r1, and the distance between the center portion O on the XY plane and the electrode 22 is r2, The diameter D1 of 22 satisfies the formula (1).

That is, assuming that the insulating member 4 and the wiring board 2 are heated to the bonding temperature T when the solder metal is melted, the solder connection portion 51 and the electrode 22 have the linear expansion coefficients α1, α2, and the center. The position is displaced according to the distances r1 and r2 between the section O and the section O. At this time, when the diameter D1 satisfies the above formula (1), the solder connection portion 51 and the electrode 22 have an overlap in the XY plane, and these can be electrically connected. The distance r1 and the distance r2 may be equal to each other.

Further, regarding the electrode 34 and the solder connection portion 51 of the semiconductor element 3 which correspond to each other, when the linear expansion coefficient of the semiconductor element 3 is α3 and the distance between the central portion O and the electrode 34 in the XY plane is r3, The diameter D2 of the electrode 34 satisfies the equation (2).

That is, assuming that the insulating member 4 and the semiconductor element 3 are heated to the bonding temperature T when the solder metal is melted, the solder connection portion 51 and the electrode 34 have the linear expansion coefficients α1, α3, and the center. The position is displaced according to the distances r1 and r3 between the section O and the section O. At this time, if the diameter D2 satisfies the above formula (2), the solder connection portion 51 and the electrode 34 have an overlap in the XY plane, and these can be electrically connected. The distance r1 and the distance r3 may be equal to each other.

The joining temperature T of the solder connecting portion 51 is appropriately set according to the melting point of the solder metal forming the solder connecting portion 51, and may be 1.05 times the melting point or 5 K higher than the melting point, for example. The reference room temperature Tr may be an assumed temperature in the room where the solder connection work is performed, and may be 20° C., for example.

FIG. 4 shows an example of the relationship between the linear expansion coefficient α1 of the insulating member 4 and the diameter D1 of the electrode 22 when the equation (1) is made equal. For example, when the diameter D1 of the electrode 22 is set to 1 mm or less, the linear expansion coefficient α1 is 130 ppm/K or less. Therefore, under this condition, the linear expansion coefficient α1 is preferably 130 ppm/K or less.

Here, specific characteristics of the insulating member 4 will be described. The linear expansion coefficient of the insulating member 4 is preferably 300 ppm/K or less, and more preferably 130 ppm/K or less as described above. The elastic modulus of the insulating member 4 is preferably 30 Mpa or less. Examples of materials that satisfy these characteristics include fluororubber and silicone.

The semiconductor unit 1A is mounted in, for example, a vehicle-mounted electronic device such as a head-up display device, or mounted in an electronic device having a heat source. The temperature of the semiconductor unit 1A rises depending on the usage state of the electronic device and the external environment.

At this time, the electrode 22 and the electrode 34 tend to be displaced due to the difference between the linear expansion coefficient α2 of the wiring board 2 and the linear expansion coefficient α3 of the semiconductor element 3. That is, shear stress is applied to the solder connection portion 51, and the solder connection portion 51 is deformed so as to be inclined with respect to the Z direction, whereby the stress is absorbed. The insulating member 4 has a lower elastic modulus than the solder connection portion 51 and is configured to be easily deformed, so that the deformation of the solder connection portion 51 is not hindered.

The amount of shear strain when the solder connecting portion 51 is deformed is determined by the ratio of the dimension in the XY plane of the solder connecting portion 51 and the dimension in the Z direction, and the larger the Z direction dimension of the solder connecting portion 51, the greater the shearing force. The amount of strain can be reduced.

According to this embodiment as described above, the following effects can be obtained. That is, since the solder connection portion 51 passes through the through hole 41 of the insulating member 4, the molten solder metal is held by the through hole 41 during the soldering process and is unlikely to hang down due to its own weight. Therefore, by appropriately setting the Z-direction dimension of the insulating member 4, the Z-direction dimension of the solder connection portion 51 can be increased and the stress absorption performance can be improved.

Further, since the solder connection portion 51 passes through the through hole 41 of the insulating member 4, the degree of freedom in setting the shape of the solder connection portion 51 is high, and the strength can be easily improved. Furthermore, by providing the insulating member 4 and appropriately setting the shape of the solder connection portion 51, the resonance frequency of relative vibration between the wiring board 2 and the semiconductor element 3 can be appropriately set. That is, the frequency (predicted value) of the impact applied to the semiconductor unit 1A from the outside and the resonance frequency of the relative vibration can be shifted.

Furthermore, since the insulating member 4 has a lower elastic modulus than the solder connection portion 51, the solder connection portion 51 can easily absorb stress.

In addition, since the electrodes 22 and 34 are located farther from the central portion O in the XY plane, the diameter is larger, so that when the solder metal is melted, displacement of the electrodes 22 and 34 is likely to occur. The part 51 and the electrodes 22 and 34 can be easily connected. Further, in the region where the positional displacement between the electrodes 22 and 34 is unlikely to occur, the electrodes 22 and 34 can have a small diameter to improve the density of the electrodes 22 and 34.

Further, when the linear expansion coefficient of the insulating member 4 is set to 300 ppm/K or less, the electrodes 22 and 34 are less likely to be misaligned when the solder metal is melted, and the electrodes 22 and 34 have a small diameter to reduce the electrode density. Can be improved. Furthermore, if the linear expansion coefficient of the insulating member 4 is set to 130 ppm/K or less, the positional displacement between the electrodes 22 and 34 is less likely to occur when the solder metal is melted, and the electrodes 22 and 34 are reduced in diameter to reduce the electrode density. Can be improved.

Further, if the elastic modulus of the insulating member 4 is 30 MPa or less, the insulating member 4 is unlikely to become a resistance when the solder connecting portion 51 is deformed, and the solder connecting portion 51 can have a long life. Furthermore, if the coefficient of linear expansion of the insulating member 4 is 300 ppm/K or less and the elastic modulus is 30 MPa or less, the life of the solder connection part 51 can be further extended.

[Second Embodiment]
As shown in FIG. 5, the semiconductor unit 1B of the present embodiment includes a wiring board 2, a semiconductor element 3, an insulating member 4, an electrical connecting portion 5, and a connecting portion 6. That is, the semiconductor unit 1B of the present embodiment is obtained by adding the connecting portion 6 to the semiconductor unit 1A of the first embodiment.

The connecting portion 6 is formed of an insulating material in a columnar shape extending in the Z direction, and connects the wiring board 2 and the semiconductor element 3 to each other, whereby the wiring board 2 and the semiconductor element 3 relatively move in the XY plane. It becomes impossible. The connecting portion 6 may have a cylindrical shape or a prismatic shape. The insulating member 4 penetrates the connecting portion 6, whereby the insulating member 4 is fixed to the wiring board 2 and the semiconductor element 3 and cannot move relative to each other in the XY plane.

In the present embodiment, since the connecting portion 6 is provided, the center (deformation reference position) when the wiring board 2, the semiconductor element 3, and the insulating member 4 are thermally deformed is the position where the connecting portion 6 is provided. Becomes At this time, the center of the connecting portion 6 may be the deformation reference position, or the outer peripheral portion of the connecting portion 6 may be the deformation reference position.

According to this embodiment as described above, the following effects are obtained in addition to the effects of the first embodiment. That is, since the wiring board 2 and the semiconductor element 3 are immovably connected to each other in the XY plane, external factors (hot air, vibration, difference in friction coefficient between members, etc.) are generated during the process of melting the solder metal. Etc., it is possible to suppress the positional displacement of the entire semiconductor element 3 with respect to the wiring board 2.

Further, since the insulating member 4 is immovable in the XY plane with respect to the wiring board 2 and the semiconductor element 3, the insulating member 4 as a whole is prevented from the wiring board 2 and the semiconductor element 3 due to the external factors. Can be suppressed from being displaced.

The present invention is not limited to the above-described embodiment, but includes other configurations and the like that can achieve the object of the present invention, and the following modifications and the like are also included in the present invention.

For example, in the first embodiment, the insulating member 4 has a lower elastic modulus than the solder connecting portion 51, but the insulating member 4 deforms because the solder connecting portion 51 absorbs stress. What is necessary is just to have an elastic modulus that allows the above.

In addition, in the first embodiment, the electrodes 22 and 34 are circular, and the diameter of the electrodes located farther from the central portion O is larger. However, the electrodes of the wiring board and the semiconductor element are rectangular or the like. In addition to the above shape, the size in the deformation direction may be increased as the distance from the central portion O increases. At this time, the deformation direction is a direction connecting the central portion O and each electrode.

In the first embodiment, the electrodes 22 and 34 located farther from the central portion O have a larger diameter, and the diameters D1 and D2 of the electrodes 22 and 34 satisfy the expressions (1) and (2). However, the diameters (dimensions in the deformation direction) of the wiring board and the electrodes of the semiconductor element may be set appropriately. For example, it is possible to measure in advance how much the temperature of each member rises when the solder metal is melted, and use the temperature of each member instead of the melting temperature T in the formulas (1) and (2). In addition, when the required number of electrodes is small or the required electrode density is low, the diameters (dimensions in the deformation direction) of the plurality of electrodes may be equal to each other.

Further, in the first embodiment, the linear expansion coefficient of the insulating member 4 is preferably 300 ppm/K or less, and the elastic modulus is preferably 30 MPa or less, but each characteristic of the insulating member 4 is The wiring board 2, the semiconductor element 3, and the connecting portion 51 may be appropriately set according to their materials, shapes, characteristics, and the like.

Further, in the second embodiment, since the insulating member 4 penetrates the connecting portion 6, the insulating member 4 is immovable in the XY plane with respect to the wiring board 2 and the semiconductor element 3. However, the connecting portion may connect the wiring board 2 and the semiconductor element 3 outside the insulating member 4. Further, by disposing a plurality of connecting portions so as to surround the insulating member 4, the insulating member 4 may be immovable with respect to the wiring board 2 and the semiconductor element 3 in the XY plane.

Besides, the best configuration, method, and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, the present invention is mainly illustrated and described mainly with respect to specific embodiments, but is not limited to the embodiments described above without departing from the technical idea and the scope of the object of the present invention. Those skilled in the art can make various modifications.

Therefore, the description of limiting the shape, the material, and the like disclosed above is given as an example for facilitating the understanding of the present invention, and does not limit the present invention. The description of the members whose names exclude some or all of the limitations of their shapes and materials are included in the present invention.

Examples of the present invention will be described below.

In the semiconductor unit 1A of the first embodiment, the elastic modulus of the insulating member 4 is set to any one of 1, 10, 30, 100 MPa, and the linear expansion coefficient is set to any one of 30, 100, 300 ppm/K. However, these were made into Examples 1-11. The characteristics of each example are shown in Table 1 and FIG.

With respect to the above Examples 1 to 11, the temperature rise and the temperature decrease were repeated, and the durability when the solder connection portion 51 was repeatedly deformed was evaluated by simulation. The temperature was changed between 100°C and -40°C. Table 1 shows the number of cycles of temperature increase and temperature decrease until the solder connection part 51 breaks (breaking cycle).

In Examples 1 to 8, the break cycle was 2000 times or more, and particularly good results were obtained. That is, particularly good results were obtained under the conditions of a linear expansion coefficient of 300 ppm/K or less and an elastic modulus of 10 MPa and a condition of a linear expansion coefficient of 100 ppm/K or less and an elastic modulus of 30 MPa (enclosed by a broken line in FIG. 6). region). Further, also in Examples 9 to 11, the break cycle was 300 times or more, and good results were obtained.

1A, 1B Semiconductor unit 2 Wiring board 22 Electrode 3 Semiconductor element 34 Electrode 4 Insulating member 41 Through hole 5 Electrical connection part 51 Solder connection part 6 Connection part O Center part (deformation reference position)

JP, 2001-127111, A

Claims (11)

A semiconductor unit comprising a wiring board, a semiconductor element arranged so as to overlap the wiring board, and an electrical connecting portion connecting an electrode of the wiring board and an electrode of the semiconductor element,
Further comprising an insulating member arranged between the wiring board and the semiconductor element,
The insulating member is formed with a plurality of through holes extending along the facing direction of the wiring board and the semiconductor element,
The semiconductor unit, wherein the electrical connection portion is configured to have a solder connection portion that passes through each of the plurality of through holes. The semiconductor unit according to claim 1, wherein the insulating member has a lower elastic modulus than the solder connection portion. With respect to the electrodes of the wiring board and the electrodes of the semiconductor element, with respect to a predetermined reference position in the plane as a deformation reference position, the farther from the deformation reference position, the larger the dimension in the deformation direction extending from the deformation reference position is. The semiconductor unit according to claim 1 or 2, which is characterized. Regarding the electrodes and the solder connection portions of the wiring board that correspond to each other, the linear expansion coefficient of the insulating member is α1, the linear expansion coefficient of the wiring board is α2, the joining temperature of the solder connection portion is T, and the reference When the room temperature is Tr, the in-plane distance between the deformation reference position and the solder connection portion is r1, and the in-plane distance between the deformation reference position and the electrode is r2, the electrode The semiconductor unit according to claim 3, wherein the dimension D1 in the deformation direction satisfies Expression (1).

Regarding the electrodes and the solder connection portions of the semiconductor element corresponding to each other, the linear expansion coefficient of the insulating member is α1, the linear expansion coefficient of the semiconductor element is α3, the joining temperature of the solder connection portion is T, and the reference When the room temperature is Tr, the in-plane distance between the deformation reference position and the solder connection portion is r1, and the in-plane distance between the deformation reference position and the electrode is r3, the electrode of the electrode is The semiconductor unit according to claim 3, wherein the dimension D2 in the deformation direction satisfies the expression (1).

The semiconductor unit according to claim 1, further comprising a connecting portion that connects the wiring board and the semiconductor element. The semiconductor unit according to claim 6, wherein the insulating member is fixed to the wiring board and the semiconductor element by inserting the connecting portion into the insulating member. The linear expansion coefficient of the said insulating member is 300 ppm/K or less, The semiconductor unit of any one of Claims 1-7 characterized by the above-mentioned. The elastic unit of the said insulating member is 30 Mpa or less, The semiconductor unit of any one of Claims 1-8 characterized by the above-mentioned. An electronic device comprising the semiconductor unit according to claim 1. Semiconductor unit manufacturing method for manufacturing a semiconductor unit including a wiring board, a semiconductor element arranged so as to overlap with the wiring board, and an electrical connecting portion connecting an electrode of the wiring board and an electrode of the semiconductor element And
Between the wiring board and the semiconductor element, an insulating member having a plurality of through holes extending along the facing direction thereof is arranged,
A method of manufacturing a semiconductor unit, comprising: melting a solder metal to form a solder connection portion that passes through each of the plurality of through holes, and configuring the electrical connection portion by the plurality of solder connection portions.

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