JP3039584B2 - Assembly method of semiconductor integrated circuit module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a semiconductor integrated circuit device constituting an electronic apparatus such as an information processing apparatus.
In particular, the present invention relates to a module structure for cooling a semiconductor integrated circuit element by circulating a liquid refrigerant near an integrated circuit and transmitting heat generated in the semiconductor integrated circuit element to the liquid refrigerant.

[0002]

2. Description of the Related Art Conventionally, as a cooling structure for a semiconductor integrated circuit module, an integrated circuit is installed on a wiring board disclosed in Japanese Patent Application Laid-Open No. 2-256263, for example, and a heat conductive compound is installed on the upper surface of the integrated circuit. There is a structure for cooling an integrated circuit by contacting a cooling plate through which a fluid refrigerant flows.

As another conventional example, Robert Darveaux, Iwona Turlix, Eye, E, E, E, Transactions, On, Components, Hybrids, and Manufacturing Technology, Volume 13 4
Issue, December 1990 (IEEE Transacstions on Components,
Hybirds, and Manufacturing Technology, vol. 13, N
o. 4, December 1990). In this example, the cooling performance is enhanced by using indium solder for joining between the semiconductor integrated circuit element and the cooling plate provided on the multilayer substrate. When using indium solder as a heat conductor, usually, a ribbon-shaped solder is cut to a length necessary for joining, and the cut solder is mounted on a semiconductor integrated circuit element and joined to a cooling plate by reflow.

[0004]

Among the above-mentioned conventional module structures, in the former example of Japanese Patent Application Laid-Open No. 2-256263, variation in the upper surface height of a plurality of integrated circuits is reduced.
This is supported by the ability to follow the heat conductive compound,
In order to improve the heat conductivity, the heat conductive compound must be in close contact with the integrated circuit and the cooling plate. In addition, the heat conductive compound has an extremely high viscosity in order to secure the close contact for a long time (for example, 10 years). . Generally, since a semiconductor integrated circuit module is extremely expensive, when a defect occurs in a semiconductor integrated circuit element during manufacture and during actual operation, it is necessary to replace the defective semiconductor circuit element. At this time, it is necessary to remove the cooling plate, but the electrical connection between the non-defective semiconductor circuit element and the multilayer substrate is cut off by a mechanical external force due to a large force generated at that time, and the non-defective product becomes a defective product. Things happen frequently. Therefore, it is difficult to replace only the initially defective semiconductor integrated circuit device.

[0005] In the latter case, indium solder is used for bonding between the semiconductor integrated circuit element and the cooling plate. However, although the shear strain characteristics of the indium solder are examined, the indium solder is used as a heat conductor. However, sufficient consideration has not been given to the practical problem in the case of using as a device. That is, conventionally, a ribbon-shaped solder is cut out to the length necessary for bonding, and the cut-out is placed on a semiconductor integrated circuit element and bonded to a cooling plate by reflow. It is. If it is excessive, it flows out of the side surface of the semiconductor integrated circuit element and flows into the wiring board, and there is a possibility that the electrodes of the semiconductor integrated circuit element may be short-circuited, so that the reliability of electrical connection is significantly reduced. On the other hand, if it is insufficient, the bonding between the semiconductor integrated circuit element and the cooling plate is insufficient, and good heat conduction characteristics cannot be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and a first object of the present invention is to easily repair a defective semiconductor integrated circuit device without applying an extra external force. Semiconductor integrated circuit module
A second object is to provide a method for assembling a module, and a third object is to provide a method for repair.

[0007]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a semiconductor integrated circuit device electrically connected and mounted on a multilayer wiring board and a back surface of an electrical connection portion of the semiconductor integrated circuit device. A heat conducting plate joined through a low melting point metal, a cooling structure directly in contact with the heat conducting plate or by a low-adhesion heat conducting material, and a sealing structure for sealing the semiconductor integrated circuit element from the outside air. In a semiconductor integrated circuit module having a low melting point metal, a hole for introducing or melting and removing the low melting point metal is provided in a part of the heat conductive plate to be joined to the low melting point metal, and a low melting point metal is joined to a portion where the low melting point metal is joined. This is achieved by a semiconductor integrated circuit module having a metallized layer for regulating a bonding region of a melting point metal.

The low melting point metal is generally composed of a metal having the lowest melting point among bonding and structural materials used for a semiconductor integrated circuit module.
Cd (127.7 ° C), In48Sn (117 ° C), In42Sn14
An In-based alloy such as Cd (93 ° C.) is desirable. In addition, the values in parentheses indicate the melting points.

The low-adhesive heat conductive material is preferably composed of grease mixed with metal powder, such as hydrocarbon grease mixed with metal powder having high thermal conductivity such as copper or aluminum, or silicone-based grease. Grease is preferred.

[0010] As the heat conductive plate, such as copper, aluminum, copper - tungsten alloy, Al ₃ N _4, other copper-based alloys, Ru include aluminum-based alloy.

A second object of the present invention is to form a metallized layer for regulating the bonding region in advance on the back surface of the semiconductor integrated circuit element and the heat conductive plate, which are the bonding region of the low melting point metal, Connecting and mounting the semiconductor integrated circuit element on the substrate, connecting the end face of the side wall of the heat conductive plate having an opening at a substantially central position of the semiconductor integrated circuit element to the multilayer wiring board, and sealing hermetically; A step of joining the gap between the semiconductor integrated circuit element and the heat conducting plate with a low melting point metal by inserting a low melting point metal solder rod into the heat melting plate, and a step of connecting a cooling structure via a heat conducting material. This is achieved by a method for assembling a semiconductor integrated circuit module having the above.

Preferably, in the step of connecting the end surface of the side wall of the heat conductive plate having an opening at a substantially central position of the semiconductor integrated circuit device to the multilayer wiring board and hermetically sealing it, further opening holes are formed at the four corners of the semiconductor integrated circuit device. It is desirable to dispose at a position corresponding to. The excess or deficiency of the low melting point metal can be measured through these opening holes and adjusted to an appropriate amount.
A third object of the present invention is to provide a semiconductor integrated circuit module repair method for disassembling a semiconductor integrated circuit module capable of achieving the first object and replacing defective semiconductor integrated circuit elements with non-defective ones. Removing the cooling structure connected via the thermally conductive material;
Heating and melting the low-melting-point metal joining the gap between the semiconductor integrated circuit element and the heat-conducting plate from the opening hole by vacuum suction and removing, and after the low-melting-point metal is removed, the heat-conducting plate is multilayered. This is achieved by a method for repairing a semiconductor integrated circuit module, comprising a step of separating from a wiring board and a step of repairing a semiconductor integrated circuit element.

[0013]

When the module is assembled, the multi-layer wiring board and the heat conductive plate are mechanically or soldered to each other by means of an opening provided in the heat conductive plate, and then a low-melting point metal is poured through the opening to form a semiconductor integrated circuit device. Bond with the heat conductive plate. Further, by installing a cooling structure having a built-in liquid refrigerant in the heat conductive plate via a low viscoelastic heat conductive material, the thermal resistance between the semiconductor integrated circuit element and the liquid refrigerant can be significantly reduced. it can.

When disassembling the module, the cooling structure is first separated from the heat conducting plate by applying a mechanical force. The force acting during this separation is directly transmitted to the heat conductive plate, and no mechanical external force is directly applied to the semiconductor integrated circuit device by mechanically supporting the heat conductive plate. Does no harm.

Further, when removing the junction of the low-melting metal between the heat conductive plate and the semiconductor integrated circuit element, the entire module was heated to a temperature equal to or higher than the melting point of the low-melting metal and was melted through the opening provided in the heat conductive plate. By extracting the metal, the heat conductive plate and the semiconductor integrated circuit can be separated without applying a mechanical external force to the semiconductor integrated circuit element.

In joining a semiconductor integrated circuit element and a heat conductive plate with a metal having a low melting point, it is important to form a metallized layer in advance in each of the joining regions in order to regulate the joining region. Thereby, it is possible to reliably bond the low melting point metal onto the metallized layer of the predetermined pattern.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention will be described below with reference to the drawings. Example 1 (1) Structural Example of Semiconductor Integrated Circuit Module: FIG. 1 is a cross-sectional view of a semiconductor integrated circuit module according to an embodiment of the present invention, and FIG. It is. In FIG. 1, reference numeral 3 denotes a semiconductor integrated circuit element, and 1 denotes a multilayer wiring board on which a plurality of semiconductor integrated circuit elements 3 are mounted.
The semiconductor integrated circuit element 3 is electrically connected to the multilayer wiring board 1 via the solder balls 2, and the back side (the upper surface of the multilayer wiring board 1) having no electrical connection is connected via the low melting point metal 4. It is joined to the heat conducting plate 5. The heat conducting plate 5 has a side wall 5
The end face a is joined to the multilayer wiring board 1 via the sealing solder 11, thereby sealing the space 20 on the multilayer wiring board 1 on which the semiconductor integrated circuit element 3 is mounted. Further, the upper surface of the heat conductive plate 5 is connected to the cooling structure 7 via the heat conductive material 6 having low adhesiveness. Further, as shown in FIG. 2, a hole 10 for melting and supplying the low melting point metal 4 is provided in the heat conducting plate 5.
Are provided at positions substantially corresponding to the center position of the semiconductor integrated circuit element 3 and at the four corners (indicated by reference numeral 13). In addition,
A metallization layer 21 is formed in advance in a bonding region of the semiconductor integrated circuit element 3 and the heat conductive plate 5 for bonding the low melting point metal 4, and the bonding region is regulated by the metallization layer, and a low melting point is formed in an unnecessary region. Metal 4 does not flow out.

The heat generated from the semiconductor integrated circuit device 3 is
Mainly low melting point metal 4, heat conductive plate 5, low adhesive heat conductive material 6,
The semiconductor integrated circuit element 3 is cooled by conducting the refrigerant 12 flowing through the cooling passage 7 through the cooling structure 7. The semiconductor integrated circuit module uses He gas, etc. in its space to avoid reliability degradation due to the action of moisture in the atmosphere.
It has a sealed structure that is sealed in 20 to block outside air. on the other hand,
When an element failure occurs in the semiconductor integrated circuit element 3, it is common practice to remove only the failed element and reattach a normal element (this is called repair). Therefore, the semiconductor integrated circuit module needs to have a structure capable of repairing the semiconductor integrated circuit element 3. For this reason, the joint portion of the semiconductor integrated circuit module needs to have detachability corresponding to repair. For this reason, in this embodiment, indium solder In48Sn (melting point 117 ° C.) is used for the low melting point metal 4, Sn37Pb (melting point 183 ° C.) is used for the sealing solder 11, and Sn is used for the solder ball 2.
3Ag (221 ° C.) was used, and the melting point of the low melting point metal 4 was the lowest among the constituent materials of the semiconductor integrated circuit module. Aluminum nitride (Al ₃ N ₄ ) is used as the heat conducting plate 5, hydrocarbon-based grease mixed with aluminum powder is used as the low-adhesion heat conducting material 6, and the cooling passage 7 is made of a coolant passage 9 through the aluminum nitride. And water was used as the refrigerant 12.

The heat conductive material 6 can be made of a low melting point solder other than grease. In this case, a solder having a melting point lower than the melting point of the low melting point metal 4 is used. Accordingly, in this case, the solder having the lowest melting point among the constituent materials of the semiconductor integrated circuit module is the heat conductive material 6 and then the low melting point metal 4.

In this example, a Cr layer was used as a metallized layer formed in a region where the low melting point metal 4 was bonded.
The metallized layer was formed by forming a film by sputtering Cr and patterning the sputtered film into a predetermined shape. That is, when formed on the semiconductor integrated circuit element 3, a region where a ring-shaped metallized layer is not formed is left around the periphery so that the indium solder 4 does not flow out to the side surface, and the heat conductive plate 5 is not formed.
In the case of forming the semiconductor integrated circuit element 3, it was formed in a region inside the semiconductor integrated circuit element 3 so as not to exceed the projection plane.

(2) Method of assembling semiconductor integrated circuit device module: First, as shown in FIGS.
The semiconductor integrated circuit device 3 is connected thereon using the solder balls 2. Next, on the multilayer wiring board 1, the side end face of the heat conductive plate 5
5a is joined using the sealing solder 11.

Next, the low melting point metal 4 is
Is injected into the gap between the heat conduction plate 5 and the heat conduction plate 5, and these are joined with the low melting point metal 4. As shown in the schematic drawing of the low-melting-point metal pouring in FIG. 2, this joining method is performed by uniformly heating the whole (for example, 125 ° C.) through a hole 10 provided in the heat conductive plate 5 of the semiconductor integrated circuit module. Indium solder)
The rod 14 is inserted and melted, and the molten low-melting point metal is used as a semiconductor integrated circuit element by utilizing the surface tension of the molten low-melting point metal 4.
The semiconductor integrated circuit element 3 and the heat conductive plate 5 are fixed by cooling and solidifying after pouring into a gap between the heat conductive plate 3 and the heat conductive plate 5 for a predetermined amount. At this time, the gap between the individual semiconductor integrated circuit elements 3 and the heat conductive plate 5 varies depending on the warp of the multilayer wiring board 1 and the inclination of the upper surface of the semiconductor integrated circuit element 3, so that the low melting point metal necessary for bonding is required. The amount depends on the location. A low melting point metal 4 is provided on the upper surface of the semiconductor integrated circuit
The metallized layers 21a and 21b are formed in advance in the region to be bonded (in this example, a Cr layer pattern is formed by sputtering), and the molten metal is placed on the solder ball 2 of the semiconductor integrated circuit element 3 in advance. To prevent it from flowing out. After the low-melting-point metal 4 solidifies, the solder bar 14 projecting from the upper surface of the heat conductive plate 5 is cut.

The hole 13 shown in FIG. 2 is used for measuring the gap between the semiconductor integrated circuit element 3 and the heat conductive plate 5 during assembly, and is suitable for obtaining the necessary amount of solder in advance. It is a stool. It is also convenient to check the flow state of the solder, and if the solder is insufficient, insert the solder rod 14 from the hole 13 where the lack was observed, add solder, and connect with the semiconductor integrated circuit element 3. This is convenient for increasing the contact area of the heat conduction plate 5.

After forming the low-melting-point metal 4 as described above, as a final step, a hydrocarbon-based grease (a heat-conductive compound) mixed with aluminum powder is coated on the upper surface of the heat-conductive plate 5 as a heat-conductive material 6. The cooling structure 7 is pressed from above with a predetermined pressure to secure a contact area between the cooling structure 7 and the heat conduction compound 6. With the above assembly procedure, the assembly of the semiconductor integrated circuit module having the structure shown in FIG. 1 is completed.

(3) Method of repairing semiconductor integrated circuit device:
The procedure of disassembling the module when repairing the semiconductor integrated circuit element is substantially the reverse of the above (2). First,
The cooling structure 7 is removed, the heat conduction compound 6 is removed, and the upper surface of the heat conduction plate 5 is exposed. Then the whole is 125 ℃
To melt the low melting point metal 4 and suck out the molten solder from the hole 10 by vacuum suction. Then raise the total temperature to 190
° C to melt the sealing solder 11
Is removed from the multilayer wiring board 1, and the semiconductor integrated circuit element 3 is removed.
To expose.

By the above operation, the semiconductor integrated circuit device
3, and repair can be performed without applying external force other than thermal stress to the solder ball 2.

<Embodiment 2> FIG. 3 is a sectional view showing another embodiment of a semiconductor integrated circuit module. In this example, instead of the sealing solder 11 in FIG. 2, a sealing member 15 in the form of a C-ring is used for the sealing portion of the semiconductor integrated circuit element 3 and sealing is performed by a mechanical fastening force between a bolt 16 and a nut 17. This is an example. In FIG. 3, the assembly procedure of the semiconductor integrated circuit module is the same as that of the first embodiment, and the heat conductive plate 5 is connected to the multilayer wiring board 1.
After a predetermined amount of the low-melting metal 4 is melted from the hole 10 of the heat conductive plate 5 and then poured and joined. In this embodiment, a part 5b of the heat conductive plate 5 is extended to near the side surface of the semiconductor integrated circuit element 3 in order to enhance the thermal conductivity. Semiconductor integrated circuit device compared to the configuration of FIG.
The cooling effect of 3 is further improved.

The low melting point metal 4 and the semiconductor integrated circuit element 3
The area and the region to be joined to the heat conductive plate 5 are adjusted by the area and pattern of the metallized layer provided on the surfaces of the semiconductor integrated circuit 3 and the heat conductive plate 5 as in the first embodiment.

<Embodiment 3> The embodiment of FIG.
The metallized region 21a on the surface of the semiconductor integrated circuit device 3 is made smaller than the projection surface of the semiconductor integrated circuit device 3 to prevent the low melting point metal 4 from flowing out to the side surface of the semiconductor integrated circuit device 3.

<Embodiment 4> In the embodiment shown in FIG. 5, a depression 18 having a size enough to receive the semiconductor integrated circuit element 3 is formed on the surface of the heat conductive plate 5, and the metallization layer 11a is provided only in the depression 18. By providing this, the outflow of the low melting point metal 4 is further prevented. Further, in this embodiment, the taper 10a is provided in the hole 10 to enhance the fluidity of the molten low melting point metal 4.

[0031]

As described in detail above, the desired objects can be achieved by the present invention. That is, when repairing a semiconductor integrated circuit device, it has become possible to disassemble and repair the module without applying an extra external force. As a result, the manufacture and repair of the semiconductor integrated circuit module are facilitated, and the reliability of the product is also improved because no extra external force is applied to the normal semiconductor integrated circuit element to destroy the element and the electrical connection. Further, the cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor integrated circuit module according to one embodiment of the present invention.

FIG. 2 is an essential part perspective view showing a process of pouring a low-melting-point metal at the time of assembling the module.

FIG. 3 is a partial cross-sectional view of a semiconductor integrated circuit module according to another embodiment.

FIG. 4 is a partial sectional view of a semiconductor integrated circuit module according to another embodiment.

FIG. 5 is a partial sectional view of a semiconductor integrated circuit module according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multilayer wiring board, 2 ... Solder ball, 3 ... Semiconductor integrated circuit element, 4 ... Low melting point metal, 5 ... Heat conductive plate, 7 ... Cooling structure, 8 ... Connection pin, 9 ... Refrigerant passage, 10, 13 ... Holes, 11: sealing solder, 12: refrigerant, 14 ...
Low melting point metal solder rod, 15 ... C ring,
16 ... bolt, 17 ... nut,
18: recess, 18a: taper,
20: space in the module, 21: metallization layer.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsubun Kawai 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Production Research Laboratory, Hitachi, Ltd. (72) Inventor: Mitsuru Shirai 1-Horiyamashita, Hadano-shi, Kanagawa Prefecture, Hitachi, Ltd. Kanagawa Factory (56) References JP-A-60-253248 (JP, A) JP-A Sho54 −78982 (JP, A) Fully open sho 59-182940 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/36 H01L 23/40

Claims (2)

(57) [Claims] A step of forming a metallization layer for regulating a bonding region on the back surface of the semiconductor integrated circuit device and a heat conductive plate which are to be bonding regions of the low melting point metal; and forming the semiconductor integrated circuit device on a multilayer wiring board. Connection, mounting stage,
Equivalent to the center and four corners of a semiconductor integrated circuit device
Connect the side wall end face of the heat conduction plate having an opening hole at a position in the multilayer wiring board, comprising the steps of hermetically sealing at least said generally
A step of joining a gap between the semiconductor integrated circuit element and the heat conductive plate with a low melting point metal by inserting a low melting point metal solder rod into an opening hole at the center position and melting by heating, and forming a cooling structure through a heat conductive material. Connecting the semiconductor integrated circuit module. 2. The method according to claim 1, further comprising the step of measuring the excess or deficiency of the low melting point metal through an opening of a heat conductive plate disposed at positions corresponding to the four corners of the semiconductor integrated circuit element, and adjusting the amount to an appropriate amount. 2. The method for assembling a semiconductor integrated circuit module according to claim 1.