JPH06318655A - Heat-dissipating member for semiconductor chip and its manufacture - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a heat dissipation member that can maintain a uniform thickness of a solder layer formed on a surface of a base material on a chip bonding side when melted and has good solderability. [Constitution] Two rolling rolls 10 and 1 on the left and right arranged in parallel in the horizontal direction
A metal tape 1a serving as a base material 1 and a metal tape 2a serving as a solder layer 2 are inserted from above between the two and the two tapes 1a and 2a are bonded to each other to produce a laminated tape-shaped heat dissipation member body a ₁ . To do. The part of the two tapes 1a, 2a in front of the joint is expanded to a predetermined angle to form a powder reservoir 20, and the powder 3 made of a material having a melting point higher than that of the solder is supplied. Rolling rolls 10,11
The powder 3 is filled in the boundary portion of the solder layer 2 with the base material 1 by the winding force of the powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipating member for semiconductor chips (so-called heat sink) used for the purpose of improving the heat dissipating property of power devices and the like.

[0002]

2. Description of the Related Art Conventionally, this type of heat dissipation member 100 is formed by forming a solder layer 102 on one surface of a base material 101 made of, for example, copper, and mounting the chip 200 on the upper surface of the solder layer 102 and the other surface side. Mounted on the board 400 through the solder material 300,
Chip 200 by heating and melting the solder in that state
Was fixed on the substrate 400 (see FIG. 6).

By the way, in order to obtain a desired heat dissipation characteristic by the base material 101 interposed between the chip 200 and the substrate 400 in this way, the base material 101 and the chip 200 should be kept at a constant interval. Is important and this is the tip
It was also important in maintaining a predetermined thermal cycle property between the 200 and the base material 101 to prevent chip separation and conduction failure.

However, in the conventional heat dissipating member 100 having the above-described structure, since the solder layer 102 has a single-layer structure composed of only solder, its shape collapses during melting and the chip 200 tilts. There is a risk that the chips will be stuck in this state, in which case the desired heat dissipation characteristics will not be obtained, and the chip 200 and the base material 101 will not maintain the prescribed heat cycle property, and the chip 200 will be peeled off or conduction failure will occur. There was a risk of causing. To solve this, means shown in FIGS. 7 and 8 can be considered, but these also have problems as described below, and the above-mentioned problems cannot be solved.

That is, the means shown in FIG. 7 is one in which a powder 500 having a melting point higher than that of solder is placed on the upper surface of a base material 101 and a solder material 600 is placed on the powder. This is to keep the thickness (height) constant and to keep the space between the chip 200 and the base material 101 mounted on the solder material 600 at a constant interval. In this case, the powder to be placed on the top surface of the base material 101. It is difficult to uniformly disperse each of the particles 501 of 500 and maintain that state, and there is a drawback that the particles 501 move and the chip 200 tilts when the solder melts.

In addition, as shown in FIG. 8, the above-mentioned particles 501 are contained in the solder material 600 in advance. By this means, the movement of the particles 501 can be prevented, but the particles 501 existing on the solder surface fall out. In addition to the fear, there is a drawback that the amount of solder is insufficient at the location 700 where the particles 501 directly contact the base material 101 and the chip 200, resulting in poor solderability.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional circumstances, and the first object thereof is to provide a solder layer formed on the surface of the base material on the chip bonding side. To provide a heat dissipating member that can maintain a uniform thickness when melted and has good solderability,
A second object of the present invention is to provide a method suitable for manufacturing the heat dissipation member.

[0008]

In order to achieve the above-mentioned object, a heat dissipation member for a semiconductor chip according to the present invention is formed by laminating a solder layer on one surface or both surfaces of a base material having a predetermined thickness. It is characterized in that at least one solder layer is filled with a powder made of a material having a melting point higher than that of the solder in a boundary portion with the base material. The base material is preferably formed of a metal material such as Cu, Ni, or Mo. As the powder, for example, Ni, Cu, Mo, W,
Examples include ceramics, alumina, glass, BN, and the like.

Further, the heat dissipation member includes a metal tape serving as a base material between two left and right rolling rolls arranged in parallel in a horizontal direction,
A metal tape to be a solder layer is inserted from above and the two tapes are bonded to each other to produce a tape-shaped heat dissipation member main body, and the joint front part of the both tapes is expanded to a predetermined angle and the space between the two tapes is expanded. Forming a powder reservoir,
It is preferable that a powder made of a material having a melting point higher than that of solder is supplied to the powder reservoir, and the powder is filled in a boundary portion between the solder layer and the base material by a winding force of a rolling roll.

[0010]

According to the heat dissipating member of the present invention, each particle of the powder in the solder layer maintains a constant thickness (height) when the solder is melted, and the gap between the chip and the base material mounted on the solder layer is maintained. The two are bonded to each other while holding them at regular intervals. At this time, since the powder is pre-filled in the solder layer, it is possible to prevent the movement of each particle when the solder is melted. Further, since the powder is filled in the boundary portion with the base material in the solder layer, each particle can be prevented from spilling and a proper amount of solder can be secured between each particle and the chip. The characteristics are obtained.

Further, if the manufacturing method of the present invention is adopted, a powder reservoir portion which spreads at a predetermined angle is formed at a position before the joining in both metal tapes, that is, right above the two rolling rolls, and the powder reservoir portion is formed in the powder reservoir portion. As the powder is supplied, the powder accumulates in a certain amount between the metal tapes before joining, and this powder enters between both metal tapes due to the gravity in the vertical direction and the transfer of each metal tape, and at the same time becomes a solder layer metal. When the tape is rolled and bonded to the metal tape serving as the base material, a heat dissipation member can be obtained in which a certain amount of powder is uniformly contained in the boundary portion of the metal tape serving as the solder layer with the base material.

[0012]

EXAMPLES Examples will be described below with reference to the drawings. In FIG. 1 (a), a solder layer 2 is laminated on one surface of a base material 1, and a boundary portion of the solder layer 2 with the base material 1 is filled with a powder 3 made of a material having a melting point higher than that of solder. 3 shows a heat dissipation member a according to an embodiment of the present invention.

The base material 1 is made of a desired material such as Cu or Ni.
Alternatively, a metal tape made of Mo having a predetermined thickness (metal tape 1a described later) is used, and the solder layer 2 is laminated on one surface side (the upper surface side in FIGS. 1 and 2) thereof.

The solder layer 2 is made of Pb-5Sn, Pb-60Sn, or Pb-40Sn when the base material 1 is a Cu material, for example.
Or Pb-2.5 Ag-5Sn, or when the base material 1 is Ni or Mo material, a metal tape having a predetermined thickness (Pb-2.5 Ag-5Sn) (metal tape 2a described later) is used. Is bonded to one surface side of a metal tape to be the base material 1, and then both tapes are cut into a plane rectangular shape having substantially the same size as the chip b to form a laminated heat dissipation member a. A certain amount of powder 3 is uniformly filled in the solder layer 2 of the heat dissipation member a.

The metal tape used for forming the solder layer 2 is not limited to the above-mentioned one, but may be a solder material known in this technical field, such as PbSn-based solder, PbAgSn-based solder,
Examples include Pb-based solder, Sn-based solder, In-based solder, Au-based solder, and the like.

The powder 3 is a material having a melting point higher than that of the solder, for example, powder of Ni, Cu, Mo, W, ceramics, alumina, glass, BN, or the like, and is uniformly applied to the boundary portion of the solder layer 2 with the base material 1. Disperse and fill a fixed amount.

Further, each particle 3a, 3a in the powder 3 ...
It is preferable to previously form a metal film of Au, Ag, Cu, Ni or the like on the surface of or to improve the familiarity with the solder layer 2 by performing surface treatment with flux.

The heat-dissipating member a of the present embodiment having the above-described structure maintains the thickness (height) when the solder is melted by the particles 3a of the powder 3 in the solder layer 2 ... The chip b mounted on the layer 2 and the base material 1 are bonded to each other while maintaining a constant space between them (FIG. 1 (b)). At this time, since the powder 3 is filled in the solder layer 2 in advance, it is possible to prevent the movement of the particles 3a, 3a ... When the solder is melted. Moreover, since the powder 3 is filled in the boundary portion between the solder layer 2 and the base material 1, it is possible to prevent the particles 3a, 3a ... Since a proper amount of solder is secured, predetermined soldering characteristics can be obtained.

Simultaneously with or before or after the bonding of the chip b and the heat dissipation member a, the other surface side (the lower surface side in FIGS. 1 and 2) of the heat dissipation member a is placed on the substrate d via the solder material c. Then, by heating and melting the solder material c, the chip b is fixed on the substrate d via the heat dissipation member a.

The solder material c may have a single-layer structure composed only of a conventionally known solder material, but the heat dissipation member a and the board d.
In order to maintain a predetermined heat cycle between the heat dissipation member a and the chip b and to prevent defective conduction between the bonding wire e and the chip b, a wire material having a higher melting point than the solder in a solder layer having a predetermined thickness. Alternatively, a composite solder filled with powder or the like (for example, Japanese Patent Application No. 4-51217 of the prior application by the present applicant,
It is more preferable to use Japanese Patent Application No. 4-285968).

The solder material c may be formed of the same material as the metal tape used for forming the solder layer 2 described above. However, when the solder layer 2 and the solder material c are formed of different materials, both of them are formed. The melting temperature can be made different, and it is useful when it is desired to have a time difference in the bonding of the chip b and the base material 1, and the bonding of the base material 1 and the substrate d.

FIG. 3 shows a method of manufacturing the above-mentioned heat radiating member a. In FIG. 3, 10 and 11 are two rolling rolls on the left and right arranged in parallel in the horizontal direction, 1a is a metal tape to be the base material 1, and 2a is solder. With the metal tape to be the layer 2, these metal tapes 1a and 2a are inserted from above between the two rolling rolls 10 and 11. The material of the metal tapes 1a and 2a is as described above.

The rolling rolls 10 and 11 are connected to a driving source (not shown) to be rotationally driven with a predetermined driving force. The metal tapes 1a and 2a are bonded to each other with a predetermined rolling force to form a laminated tape. A heat dissipating member main body a ₁ is produced.

The rotary drive of the rolling rolls 10 and 11 may be directly connected to a drive source such as a motor, but it is not limited to this. For example, although not shown, the rolls 10 and 11 are not shown.
On the other hand, a plurality of adjusting rolls may be arranged side by side in the horizontal direction and indirectly connected to the drive roll via these adjusting rolls so that the rolling force can be finely adjusted. Further, other than arranging the warp preventing rolls of the rolling rolls side by side, changes within the known range are optional.

At the position before the joining of the respective metal tapes 1a and 2a, the metal tape 2a to be the solder layer 2 is spread at a predetermined angle by a tension roller (not shown), and thereby between the both metal tapes 1a and 2a. The powder reservoir 20 is formed.

Above the powder reservoir 20 is installed a terminal discharge port 30 of a known powder supply means such as a feeder,
A fixed amount of powder 3 is continuously supplied to the powder reservoir 20 through the discharge port 30. The opening width of the terminal discharge port 30 in the powder supply means is substantially the same as the width dimension of each metal tape 1a, 2a, and the powder 3 discharged from the discharge port 30 is uniformly supplied in the width direction of the metal tapes 1a, 2a. To do so.

Thus, according to the manufacturing method of the present embodiment as described above, the portions of both metal tapes 1a and 2a before the joining,
That is, a powder reservoir 20 that expands at a predetermined angle is formed directly above the two left and right rolling rolls 10 and 11. If a certain amount of the powder 3 is supplied to the powder reservoir 20, the powder 3 is not joined. A certain amount is accumulated between the joining surfaces of the metal tapes 1a and 2a. Further, the powder 3 is wound between the metal tapes 1a and 2a by gravity applied to the powder 3 in the vertical direction and the transfer of the metal tapes 1a and 2a by the rotational driving of the both rolling rolls 10 and 11, and at the same time. By rolling the metal tape 2a to be the solder layer 2 and joining it to the metal tape 1a to be the base material 1, a certain amount of the powder 3 is applied to the boundary portion of the metal tape 2a to be the solder layer 2 with the base material 1. The heat dissipation member a uniformly contained is obtained.

In order to manufacture the above-mentioned heat radiating member a without using such means, the above-mentioned rolling rolls are arranged vertically in the vertical direction, and the metal tape to be the solder layer 2 is placed on the upper side on the lower side. Each of the metal tapes to be the material 1 is arranged so as to be horizontally movable, and is inserted between the rolling rolls from the side, and the upper surface of the lower metal tape before joining (that is, the upper metal tape and the upper metal tape). It is conceivable that the powder 3 is sprinkled on the joint surface) using a hand sprinkler or a feeder.
However, in such a manufacturing method, it is not only difficult to uniformly disperse the powder 3 on the metal tape, but also the powder 3 supplied by the vibration due to the transfer of the metal tape spills down, and the solder layer 2 It is difficult to uniformly contain a certain amount of powder 3 therein. It is also conceivable to mix the powder 3 into a liquid such as alcohol and apply the liquid onto a metal tape. In this case, if both tapes are rolled before the liquid dries, the liquid becomes an obstacle. As a result, the joining of the tapes with each other becomes uncertain, and after the liquid is dried, the powder 3 spills down like the above-mentioned means.

The manufacturing method of the present invention eliminates all of these problems, and the powder 3 is formed at the boundary portion between the solder layer 2 and the base material 1.
The heat-dissipating member a of the present invention filled with is extremely easily and surely manufactured.

In the heat dissipation member a'shown in FIG. 4, the solder layers 2 are laminated and formed on both surfaces of the base material 1, and a material having a melting point higher than that of the solder is used at the boundary portion of each solder layer 2 with the base material 1. Another embodiment is shown in which the powder 3 is filled. still,
The constituent members of the heat dissipating member a ′ of this embodiment, that is, the base material 1, the respective solder layers 2 and 2, the material of the powder 3 and the like are the same as those described in the above embodiment, and therefore, the above description in FIG. The same reference numerals are given and the description is omitted.

In the heat dissipation member a'of this embodiment, the thickness (height) when the solder is melted is kept constant by the respective particles 3a, 3a of the powder 3 in the one solder layer 2, and the thickness (height) on the solder layer 2 is kept constant. Since the mounted chip b and the base material 1 are held at a constant interval to be bonded to each other and the powder 3 is pre-filled in the solder layer 2, each particle 3a, when the solder is melted, 3a ... can be prevented from moving. Further, since the powder 3 was filled in the boundary portion between the solder layer 2 and the base material 1, the particles 3a, 3a
... can be prevented from spilling, and each particle 3a, 3a
Since a proper amount of solder is secured between the chip and the chip b, predetermined soldering characteristics can be obtained.

Simultaneously with or before or after the bonding of the chip b, the other solder layer 2 is placed on the substrate d, and the solder layer 2 is heated and melted, and thereby the heat radiation member a'is provided. The chip b is fixed on the substrate d. At this time, similarly to the above, the thickness (height) when the solder is melted is kept constant by the respective particles 3a, 3a of the powder 3 in the solder layer 2, and the substrate d and the base material 1 are kept at a constant interval. At the same time, the two are bonded to each other, and the powder 3 is pre-filled in the solder layer 2, so that the movement of the particles 3a, 3a ... When the solder is melted can be prevented. Further, since the powder 3 is filled in the boundary portion with the base material 1 in the solder layer 2, it is possible to prevent the particles 3a, 3a ... From spilling, and between the particles 3a, 3a. Since a proper amount of solder is secured, predetermined soldering characteristics can be obtained.

The other solder layer, that is, the solder layer 2 on the side to be bonded to the substrate d, achieves the initial purpose even if it is not filled with the powder 3 but has a single-layer structure made of only a conventionally known solder material. However, in order to maintain a predetermined thermal cycle property with the substrate d to prevent peeling of the heat dissipation member a ′ and defective conduction between the chip b and the bonding wire e, the solder layer is formed as described above. It is useful to fill the boundary portion of 2 with the base material 1 with powder 3 made of a material having a higher melting point than solder.

The metal tapes used for forming the respective solder layers 2 and 2 may be formed of the same solder material, but when they are formed of different solder materials, the melting temperature of the two is different. Can be made different, which is useful when it is desired to have a time difference in the bonding between the chip b and the base material 1 and between the base material 1 and the substrate d.

FIG. 5 shows a method of manufacturing the heat dissipation member a'of this embodiment. In the figure, 10 and 11 are two rolling rolls on the left and right arranged in parallel in the horizontal direction, 1a is a metal tape to be the base material 1, 2a
Is a metal tape to be the solder layer 2, and these metal tapes 1a,
Inserting 2a and 2a between the two rolling rolls 10 and 11 from above, the tapes 2a and 2a are bonded to both surfaces of the tape 1a by the rolling force of the rolls 10 and 11, and the laminated tape-shaped heat dissipation member body a ₂ To make. Since the materials of the metal tapes 1a and 2a and the rolling rolls 10 and 11 are the same as those described in the above embodiment,
In FIG. 5, the same symbols as above are assigned and the description thereof is omitted.

Before the joining of the respective metal tapes 2a and 2a, a tension roller (not shown) is used to spread the metal tapes 2a and 2a to a predetermined angle, whereby the powder reservoir 2 is formed between the metal tapes 1a and 2a and 2a.
Form 0, 20.

Above each of the powder reservoirs 20, the terminal discharge port 30 of the well-known powder supply means is installed as in the above embodiment,
A fixed amount of powder 3 is continuously supplied to the powder reservoir 20 through the discharge port 30. The opening width of the terminal discharge port 30 in the powder supply means is substantially the same as the width dimension of each metal tape 1a, 2a, and the powder 3 discharged from the discharge port 30 is uniformly supplied in the width direction of the metal tapes 1a, 2a. To do so.

Thus, according to the manufacturing method of this embodiment,
If a certain amount of powder 3 is supplied to the powder reservoirs 20 and 20 in front of the joining of the respective metal tapes 1a, 2a and 2a, the powder 3 is applied between the joining surfaces of the metal tapes 1a, 2a and 2a before joining. Accumulate a certain amount. Further, the powder 3 is moved by gravity applied to the powder 3 in the vertical direction and the transfer of the metal tapes 1a, 2a, 2a by the rotational driving of the both rolling rolls 10 and 11, respectively.
The metal tape 2a, which becomes the solder layer 2, is rolled up between the 1a and 2a, and at the same time, the metal tape 2a that becomes the solder layer 2 is rolled and joined to the metal tape 1a that becomes the solder material 2, 2 A heat radiating member a ′ uniformly containing a certain amount of the powder 3 at the boundary with the material 1 is obtained.

When the heat dissipation member a'of this embodiment is to be manufactured without using such means, the heat dissipation member a described above is used.
As described in the description of the manufacturing method, the metal tape to be the solder layer and the metal tape to be the base material are laterally inserted between the rolling rolls arranged vertically in the vertical direction, and the upper surface of the metal tape. A method of sprinkling the powder on is conceivable. However, in such a manufacturing method, as described above, it is difficult to uniformly disperse and contain the powder, and after forming one solder layer, the same means must be repeated to form the other solder layer by lamination. I have to.

The manufacturing method of the present invention eliminates all of these problems, and the metal tapes 2a and 2a to be the solder layers 2 and 2 can be simultaneously formed on both surfaces of the metal tape 1a to be the base material 1, and the solder layers 2 and 2a can be simultaneously formed. The heat dissipating member a'wherein the powder 3 is uniformly dispersed and filled in the boundary portion between the base material 1 and the base material 2 can be manufactured very easily and reliably.

In the drawings, for the sake of convenience, each particle of the powder is shown in an enlarged manner, but it goes without saying that the actual particle diameter is extremely small, and as an example, the metal that will be the base material 1 will be used. The thickness of the tape 1a is 0.2 to 5.0 mm, the thickness of the metal tape 2a to be the solder layer 2 is 0.05 to 1.0 mm, and the thickness of the manufactured heat dissipation member a is 0.1 to 1.5 mm. 0.02
It is about 0.1 mm.

[0042]

As described above, in the heat dissipation member of the present invention, the solder layer is laminated on one surface of the base material and the powder having a melting point higher than that of the solder is filled in the boundary portion of the solder layer with the base material. The thickness (height) of the solder when melted can be kept constant by each particle, and the chips mounted on the solder layer and the base material can be joined at a fixed interval.

Therefore, by interposing between the chip and the substrate, a predetermined heat dissipation characteristic can be obtained, and a highly reliable heat dissipation member having excellent solderability can be provided.

Further, in the manufacturing method according to the present invention, two or three metal tapes are transferred in the vertical direction and the portion before the joining is expanded to supply the powder, and the powder is subjected to gravity applied in the vertical direction. Since the powder is filled by the rolling force for joining the metal tapes, for example, compared to a method of directly sprinkling the powder with a hand spreader or a feeder on the upper surface of the metal tape which is transferred in the horizontal direction, a fixed amount of powder is used. The powder can be easily and reliably contained in the solder layer uniformly. Therefore, it is possible to extremely easily manufacture the heat dissipation member of the present invention which can obtain a predetermined heat dissipation characteristic and has good solderability.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of a heat dissipation member for a semiconductor chip according to the present invention.

FIG. 2 is a vertical cross-sectional front view showing a usage state of a heat dissipation member according to the present invention.

FIG. 3 is a vertical sectional front view showing a method for manufacturing a heat dissipation member of the present invention.

FIG. 4 is a vertical sectional front view showing another embodiment of the heat dissipation member for a semiconductor chip according to the present invention.

5 is a vertical cross-sectional front view showing the method of manufacturing the heat dissipation member shown in FIG.

FIG. 6 is a vertical cross-sectional front view showing the procedure for attaching the heat dissipation member.

FIG. 7 is a vertical cross-sectional front view showing a procedure for attaching a conventional heat dissipation member.

FIG. 8 is a vertical cross-sectional front view showing a procedure for attaching a conventional heat dissipation member.

[Explanation of symbols]

a, a ': heat dissipation member 1: base material 2: solder layer
3: Powder 3a: Particles 1a: Metal tape as base material 2a: Metal tape as solder layer b: Chip c: Solder material d: Substrate 10, 11: Rolled tape

Claims (3)

[Claims] 1. A solder material is laminated on one or both sides of a base material having a predetermined thickness, and a material having a higher melting point than solder is formed at a boundary portion of at least one solder layer with the base material. A heat dissipation member for a semiconductor chip, characterized by being filled with powder. 2. The heat dissipation member for a semiconductor chip according to claim 1, wherein the base material is made of a metal material such as Cu, Ni or Mo. 3. A laminated tape in which a metal tape to be a base material and a metal tape to be a solder layer are inserted from above between two left and right rolling rolls arranged side by side in a horizontal direction and the two tapes are bonded to each other. A heat dissipating member main body is formed, and a part of the both tapes before joining is expanded at a predetermined angle to form a powder reservoir between the tapes, and the powder reservoir is made of a material having a higher melting point than solder. 2. The method for manufacturing a heat dissipation member for a semiconductor chip according to claim 1, wherein the powder is supplied to fill the boundary portion of the solder layer with the base material by the winding force of the rolling roll.