JP2002353388A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device with excellent radiation and high reliability reducing easing strain by surely embedding a thermal conduction member at low load without producing a gap between an electronic part including a heat generating element and a casing and its manufacturing method. SOLUTION: The semiconductor device having a low load radiation mounting structure is realized for the casings 5, 6 and a semiconductor package 2 even when the compression rate of a thermal conduction rubber sheet 8 is high by utilizing the stress relaxation of the thermal conduction rubber sheet 8 under a low temperature heating environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and considers that a semiconductor device mounted on a wiring board has good heat dissipation in a housing and reduces distortion due to external stress. The present invention relates to a semiconductor device suitable for a semiconductor device housed in such a manner, particularly a semiconductor device including a high-speed optical communication element, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Means for dissipating heat from an electronic component having a heating element mounted inside an electronic device to the outside include:
A general method is to attach a heat radiation fin to the upper surface of the electronic component and dissipate heat into the air inside the housing via the heat radiation fin.

However, for example, in order to rapidly reduce the size and thickness of electronic devices typified by mobile devices and portable telephone devices, it is sometimes difficult to adopt a heat radiation form that requires a space volume such as a radiation fin. The heat radiation method using the housing of the electronic device itself as a heat radiation medium is becoming important.

In this case, a heat radiation system in which heat from an electronic component including a heating element mounted on a wiring board is radiated from the substrate side to the housing through a member having high thermal conductivity, and a heat radiation system from the electronic component directly to the housing. Has been proposed.

For example, in the invention disclosed in Japanese Patent Application Laid-Open No. 11-163564, a wiring board on which electronic components are mounted (hereinafter abbreviated as a mounting board) is mounted on a housing via an elastic body having high thermal conductivity. By fixing, a method of realizing heat radiation from the electronic component to the mounting board and from the mounting board to the electronic device housing is proposed.

In the invention disclosed in Japanese Patent Application Laid-Open No. 08-139236, a highly thermally conductive member (here, grease) is filled between a housing and a heat sink attached to the upper surface of a heating element. It proposes a method of realizing heat radiation from the electronic component directly to the housing by fixing.

[0007]

Considering the heat radiation efficiency, when trying to take a heat radiation path through a mounting board, a mother board (wiring board) of a generally used electronic device has a low thermal conductivity FR. In most cases, it is an organic material such as -4, so that the heat radiation efficiency deteriorates.

Therefore, it is the shortest heat radiating route and the heat radiating method having the highest heat radiating efficiency to radiate heat directly from the heat-generating electronic components such as the semiconductor device to the housing housing the mounting substrate.

However, for example, Japanese Patent Application Laid-Open No. 08-23 / 08
Fixing the gap between the electronic component on the mounting board and the housing with a filling member such as grease as disclosed in Japanese Patent No. 36, managing the application amount and uniformity of the application surface,
The repair process when the electronic component is defective is very troublesome, and further requires a new high-temperature heating process for hardening the grease.

On the other hand, there is a method in which a silicone-based rubber sheet is sandwiched in a gap between an electronic component and a housing, so that heat can be radiated through the shortest heat radiating path as in the case where grease is filled and fixed.

In this case, since it is only necessary to place the rubber sheet on the electronic component, there is a feature that the process can be easily controlled and a low-cost process can be used, and the subsequent repair is easy.

However, in this heat radiation system, the management of the gap between the electronic component and the housing is very important. If the actual gap is larger than the assumed gap, the sheet cannot fill the gap and the heat radiation efficiency is extremely high. If it gets worse and conversely, if it is smaller than the assumed gap, the compression rate of the sheet generated when storing the electronic components in the housing will be higher than the original design value, and a high load will be applied to the electronic components and the housing. Problem.

Further, in the heat conductive member of the silicone rubber type, since the heat conductivity changes according to the filling amount of the filler to be filled in the member, the higher the heat conducting specification, the larger the filling amount and the higher the hardness. , And a higher load is applied to the same compression ratio.

In particular, in a high-speed optical communication module or the like in which electronic components housed in a housing use an optical system, the mounting positioning accuracy of components is very important in designing to reduce transmission loss. It is not preferable to deform the module board on which the housing and the electronic components are mounted.

Further, in a module on which electronic components generating a large amount of heat are mounted, it is desirable to use an aluminum material having a high thermal conductivity as a casing material. It is also important to change the high metal housing to a plastic housing, and in any case, the housing is going to be less rigid in terms of strength,
It is not appropriate to increase the compressibility of the sheet and apply a high load.

On the other hand, in terms of design, the gap between the electronic component and the housing becomes wider than the initial thickness of the sheet, and it is absolutely necessary to avoid leaving a slight gap. for that reason,
In consideration of dimensional errors in the thickness direction of the housing and variations in the mounting height of electronic components, it is necessary to design at a considerably high compression ratio. Therefore, it is expected that high loads will be applied to the electronic components and the housing during the normal assembly process, and as an ideal function, a heat dissipation method that can mount the rubber sheet with a lower load even if the sheet compression ratio is high has been established. There is a need to.

[0017] The object of the present invention has been made in view of such a viewpoint.
A reliable semiconductor device in which the heat conduction member is reliably embedded at a low load without generating a gap between the electronic component including the heating element and the housing, and the heat dissipation is improved to reduce the housing distortion. It is to provide a manufacturing method thereof.

[0018]

A feature of a semiconductor device that can achieve the above object of the present invention is that a wiring board,
A semiconductor device electrically connected to and mounted on the wiring substrate via an electrode connecting conductive material, a housing for housing the wiring substrate and the semiconductor device, and a gap between the semiconductor device and the housing. A semiconductor device provided with a heat conductor that conducts heat of the semiconductor device to a housing, wherein the housing is divided into an upper housing and a lower housing having openings, and A fitting for accommodating the semiconductor device mounted on the wiring board and the heat conductor in the housing at a peripheral portion of the housing while having a structure in which one opening fits into the other opening. It has bonding / compression bonding means, and the thermal conductor is softer than the conductive material for electrode connection at normal temperature, and
A compressive load when heated in a temperature range higher than room temperature is made of a thermally conductive elastic body that is smaller than a compressive load at room temperature, and is heated and compressed in a gap between the semiconductor device and a housing in the temperature range. It is in.

Preferably, an optical element having an electrode terminal electrically connected to the semiconductor device on the wiring board and an optical terminal connected to an optical fiber is held on the inner wall of the housing. That is. Thus, a semiconductor device including a high-speed optical communication element can be realized. The optical element includes a light emitting element such as a light emitting diode (LED) or a semiconductor laser which converts an electric signal into an optical signal, and a light receiving element which converts an optical signal into an electric signal. As the wiring substrate, a wiring substrate made of ceramics is generally used, but a multilayer wiring substrate made of a heat-resistant resin may be used depending on the application. On this wiring board, a bare chip of a semiconductor element, a semiconductor package, and the like are mounted as mounted components. Solder is generally used as a conductive material for electrode connection for electrical connection between the mounted component and the wiring board, but a conductive adhesive other than solder can also be used.

The housing needs a certain strength to house the semiconductor device and protect it from the outside, but has a high thermal conductivity to efficiently release the heat from the housed semiconductor device to the outside. It is composed of materials. Further, a material having good workability is desirable from the viewpoint of molding the casing, and for example, a metal material such as aluminum, an aluminum alloy, a copper-zinc alloy (brass) is used. In addition, depending on the application, plastics filled with metal or ceramic powder as a filler to enhance thermal conductivity can be used. To describe the structure of the housing, a housing having a predetermined depth divided into an upper housing and a lower housing has one of the housings fitted to the other housing and has a peripheral portion. Established,
For example, both are removably crimped and fixed by a fitting crimping means such as a screw structure or a tightening structure using a spring or a pin.

When housing the wiring board on which the semiconductor device is mounted in these housings, the wiring board on which the semiconductor device is mounted is inserted into one housing, and then the other housing is fitted. Then, it is crimped and fixed by crimping means provided on the peripheral portion.

The dimensional relationship of the housing will be described in detail. When this crimping and fixing is performed, a gap narrower than the uncompressed thickness of the heat conductor mounted between the back surface of the semiconductor device and the inner wall surface of the housing behind the semiconductor device. Designed to be formed. Accordingly, by compressing and fixing the housing, the heat conductor inserted in the gap is compression-mounted. The degree of compression of the heat conductor can be recognized as long as the heat conductor is slightly compressed. However, it is preferable that the heat conductor is compressed within a range of 40 to 70% of the thickness of the heat conductor before compression. It is desirable to compress and fix the housing as described above.

A detailed description of the heat conductor used in the present invention based on experimental facts will be given in the section of “Embodiments of the Invention”. Here, the outline of the material, shape, dimensions, etc. of the heat conductor will be described. I do.

First, the material of the heat conductor is, for example, 1.0 to 10.0 because one of its functions is to efficiently conduct heat generated from the semiconductor device to the housing.
It is desirable to have a thermal conductivity of about W / m · K.

Further, since the heat conductor is compression-mounted in the gap between the semiconductor device housed in the housing and the inner wall of the housing, it must have a specific elasticity as described above. Therefore, the thermal conductor used in the present invention has thermal conductivity and elasticity, and can be defined as a thermally conductive elastic body.

It is important that the heat conductor used in the present invention be compressed and mounted in the gap with a low load even if the compression ratio during compression mounting is high. Is electrically connected, for example, softer at room temperature than a conductive material for electrode connection such as solder, and
The compression load when heated in a temperature range higher than room temperature is smaller than the compression load at room temperature. A preferable elastic modulus at normal temperature (synonymous with room temperature) is 0.5 to 5.0M.
Pa range.

When the deformation resistance of the heat conductor is represented by a load required per unit compressibility, the deformation resistance at 100 ° C. is 1/3 to 1/2 of the deformation resistance at 30 ° C. Desirably.

The preferred shape of the heat conductor is a sheet shape, and the dimensions of the sheet are larger than the gap between the semiconductor device housed in the housing and the inner wall of the housing. The thickness is selected in consideration of being mounted in the gap with 70% compression.

The heating of the heat conductor is carried out at a temperature higher than room temperature, preferably 50 to 100 ° C. The timing of the heating is as follows: After being fixed, it may be heated and held at the predetermined temperature.

As a method of mounting the heat conductor, an adhesive having good heat conductivity is temporarily attached to the back surface of the semiconductor device including the heating element or the inner wall surface of the housing facing the semiconductor device so as not to displace. It is desirable to keep it fixed.

As a preferable sheet material to be a heat conductor, a rubber material having a high heat conductivity, such as a silicone rubber sheet, which generally has a low heat resistance, is excellent in flexibility and tackiness, and is capable of adjusting the hardness. Sheet.

The preferable properties of the rubber sheet required here include a sealing material (referred to as an underfill resin) for reinforcing a conductive material for electrode connection such as solder or Au bump.
For example, the rigidity is lower than that of a mounting substrate such as a module substrate, but the thermal conductivity is high, and a material having such characteristics is used as a rubber sheet constituting a thermal conductor.

The following is an example of the configuration of the semiconductor device of the present invention.
A practically preferable semiconductor module is housed in a housing. Therefore, a wiring board is used as a module board, and a semiconductor device mounted thereon is used as a semiconductor package. That is, a feature of the present invention is a module substrate, a semiconductor package electrically connected and mounted on the module substrate via a first solder, and a housing for accommodating the module substrate and the semiconductor package. A semiconductor device, comprising: a heat conductor that is disposed in a gap between the semiconductor package and a housing and conducts heat of the semiconductor package to the housing, wherein the housing has an opening with respect to each other. It is divided into a body and a lower housing, and has a structure in which one opening fits into the other opening, and a semiconductor package mounted on the module substrate is connected to the periphery of the housing by heat. The semiconductor package includes a crimping means for housing and holding the conductor in a housing, and the semiconductor package is electrically connected to and mounted on a package substrate via a second solder. The heat conductor is softer at room temperature than the first and second solders, and has an elasticity such that a compression load when heated in a temperature range higher than room temperature and lower than a solder reflow temperature is smaller than a compression load at room temperature. The semiconductor package is heated and compressed and mounted in the gap between the semiconductor package and the housing in the temperature range.

A feature of the method of manufacturing a semiconductor device that can achieve the object of the present invention is that a semiconductor device having a heating element is electrically connected and mounted on a wiring board via a conductive material for electrode connection. And a step of accommodating a wiring board on which the semiconductor device is mounted in a housing divided into an upper housing and a lower housing, the method comprising: In the step of housing the wiring board on which the is mounted in the housing, a heat conductive elastic body is inserted into a gap between the semiconductor device and the housing, and the upper housing and the lower housing are fitted and crimped. A step of compressing and mounting the heat conductive elastic body in a gap between the semiconductor device and the housing, and holding and fixing the wiring board between an upper housing and a lower housing, wherein the heat conductive elastic body includes Conductive for electrode connection at room temperature Softer than the material, and, when heated in a temperature range higher than room temperature, the compressive load is made of a sheet-like thermally conductive elastic body smaller than the compressive load at room temperature, and as a post-process of housing the wiring board in a housing And a step of heating and holding the housing accommodating the wiring board in a temperature environment of 50 to 100 ° C.

Also, as described above, this housing is 50 to 1
Instead of adding a step of heating and holding under a temperature environment of 00 ° C., the heat conductive elastic body is compression-mounted in a gap between the semiconductor device and the housing, and the wiring board is mounted on an upper housing and a lower housing. In the process of clamping and fixing with
The heating and holding may be performed in a temperature environment of 00 ° C.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION The characteristics required of a heat conductor, which is a basic component of the present invention, and the basic principles of a semiconductor device of the present invention and a method of manufacturing the same using the same will be described below. This will be specifically described with reference to the drawings.

FIG. 5 shows an experimental method for measuring the mechanical properties of a silicone rubber sheet having a high thermal conductivity as a thermal conductor. The rubber sheet 8 having a constant thickness was sandwiched between the rigid cylindrical jigs 51a and 51b, and compressed at a constant displacement speed of 0.01 mm / s.

FIG. 6 shows, from the experiment shown in FIG. 5, the compression ratio of the rubber sheet 8 (the ratio of the crushing amount to the initial thickness: expressed in units of% on the horizontal axis) and the compression load (units of kgf on the vertical axis). This is the result of measuring the relationship of (display) at room temperature (25 ° C.). Materials A and B in the figure are materials having different thermal conductivity (rubber sheet).
8), in the case of material A (5.6 W / m · K) having a high thermal conductivity, the compressive load for the same compressibility is larger than that of material B (2.5 W / m · K) having a low thermal conductivity. It can be seen that as the compression ratio increases, the difference becomes more pronounced (upward right characteristic).

FIG. 7 shows the results of measuring the change in the compression load when the two materials A and B shown in FIG. 6 were displaced and held at room temperature while being compressed to a compression ratio of 35%.
The abscissa in the figure indicates the retention time in seconds (s). It can be seen that when the displacement is maintained after compression, rapid stress relaxation occurs at an early stage, and the compression load becomes almost constant after a certain period of time.

FIG. 8 shows the results of a similar test performed on the material A having a high thermal conductivity in FIG. 7 in a furnace environment at 80 ° C. In an environment of 80 ° C., the initial compressive load for the same compressibility is reduced due to the softening of the sheet material itself, and the stress relaxation after the displacement holding is reduced by 2 at room temperature.
It can be seen that the saturation occurs at about 0 to 30%, whereas at 80 ° C., the compression load is reduced to almost zero with a short holding time.

From the results of the above study, it can be seen that heat is radiated from an electronic component having a heating element (including at least a semiconductor device) to a housing (not shown in the drawing) via the highly heat-conductive rubber sheet 8. If the housing assembly is performed not in a normal room temperature environment but in a low-temperature heating environment where the influence on other semiconductor components is small, the compression rate of the rubber sheet 8 must be designed to be high. In this case, it can be seen that the load on the housing and the electronic components can be significantly reduced.

FIGS. 9 and 10 show sheet materials 8 using an actual product module housing (defined as a semiconductor device in the present invention).
This is the result of experimentally examining the load on the housing that occurs when assembling the housing using the heat-dissipating mounting structure using the EMI. FIG. 1A is an external plan view, and FIG. 1B is a cross-sectional view.

The housing used for the evaluation is composed of an upper housing 5 and a lower housing 6 made of aluminum, and has a structure in which the upper housing 5 is fitted into the lower housing 6. Module board
The screw 9 penetrates the mounting holes 3a provided at the four corners of 3 and the four corners of the upper housing 5 and the lower housing 6 are tightened with the screws 9, so that the semiconductor module 100 (to be precise, mounted on the module substrate 3) The thermally conductive rubber sheet 8 inserted on the back of the semiconductor package 2) is mounted in a compressed state. Note that a heat generating element (element such as a semiconductor chip) 1 is mounted on the module substrate 3, and a semiconductor package 2 sealed with a Cu cap 7 is mounted and connected via a solder bump 4.

As shown in FIG. 9, a strain gauge 14 is attached to the surface of the upper housing 5 corresponding to the center of the mounting area 100a of the semiconductor package 2 having the heating element 1, and the gauge output at the time of assembling the housing. The load on the housing was measured indirectly from the change.

FIG. 10 shows the rubber sheet material 8 between the upper surface of the semiconductor package 2 and the housing (more precisely, a shallow concave groove 6a corresponding to the mounting area 100a of the semiconductor package 2 provided on the inner wall of the upper housing 5). 5 shows a result of measuring a change in strain output on the surface of the housing when the housing is compressed and mounted via the. In the figure, the left vertical axis indicates the holding temperature (° C.) of the housing, the right vertical axis indicates the housing strain (unit: με), and the horizontal axis indicates the holding time (unit: minute).

When the housing is assembled by screwing in a room temperature environment, the rubber sheet 8 inserted in the gap between the upper surface of the semiconductor package 2 and the housing is compressed and deformed, and tensile strain is generated on the housing surface. ing. As shown, the strain reaches a peak early in the retention time. After that, the stress relaxation gradually progresses with the rise of the housing temperature, and it can be seen that the stress relaxation occurs rapidly near the temperature of the housing surface exceeding 50 ° C.

From this measurement result, it is expected that the increase in stress relaxation under the heating environment as shown in FIG. However, unlike the result of FIG. 8, the progress of the stress relaxation stopped halfway, as shown in FIG.
Was used in the form of a groove.
8 becomes embedded in the groove of the housing after assembling the housing, and if crushing deformation progresses to a certain extent,
It is probable that the relief for the deformation of the sheet material 8 itself was lost, and the boundary conditions were close to the hydrostatic pressure. Therefore, it is important that the shape of the housing side that comes into contact with the sheet material has a structure in which deformation around the sheet material is not restricted.
In FIG. 10, the predicted value without the groove is plotted, but the measured value almost similar to this is obtained.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. <First Embodiment> FIG. 1 is a sectional view showing an outline of a semiconductor device according to a first embodiment of the present invention. FIG. 3 and FIG. 4 are cross-sectional views showing manufacturing steps in which the heat treatment timing of the high thermal conductive rubber sheet 8 is different.

In this embodiment, a module structure for high-speed communication will be described as an example. A semiconductor package 2 having a BGA (Ball Grid Array) structure on which a high-speed communication element 1 is mounted as a semiconductor element is mounted on a module substrate 3 via solder bumps 4 (referred to as second solder in the present invention). The semiconductor module 100 accommodated in the housing is configured. Note that the heating element 1 in the drawing shows a case of one chip, but a plurality of multi-chip packages (MCM)
The same applies to the structure.

The housing for housing the semiconductor module 100 is
It is composed of two members, an upper case 5 and a lower case 6, and has a structure in which the upper case 5 is fitted into the lower case 6. These housings are made of aluminum here in order to enhance the heat radiation effect. However, the housing material may be another metal material or a plastic material. However, in the case of a plastic material, it is desirable to enhance the thermal conductivity by, for example, filling a filler.

The module substrate 3 on which a plurality of semiconductor packages 2 are mounted is fixed inside the upper and lower casings 5 and 6 by screw fastening 9 through installation holes 3a provided at four corners thereof.

Semiconductor package 2 on which heating element 1 is mounted
A gap is formed in advance between the upper surface of the Cu cap 7 and the upper housing 5 in consideration of the amount of insertion of the rubber sheet 8 having high thermal conductivity after screwing.

The high thermal conductive rubber sheet 8 (industrial silicone rubber sheet) is used to realize high thermal conductive properties.
In this example, the configuration is such that high deformability and high thermal conductivity are achieved by highly filling a silver-based filler. Although the thermal conductivity varies depending on the type of the filler, it is a material having a thermal conductivity of about 2 to 6 W / m · K, and the hardness increases as the thermal conductivity increases.

The clearance t1 (corresponding to the thickness of the compressed rubber sheet 8) between the inner wall surface (projection 5a) of the upper housing 5 and the upper surface of the semiconductor package 2 is determined in the thickness direction of the housings 5 and 6. It is designed to be smaller than the initial thickness t2 of the rubber sheet 8 in consideration of the dimensional variation, and usually needs to be designed with an estimated compression ratio of 30% or more. In this example, the preferable compression ratio t1 is designed to be 40 to 70% of t2.

The semiconductor package 2 mounted on the module substrate 3 has a structure in which a Cu cap 7 is attached to the upper surface of the heating element 1 since this example is an embodiment particularly considering heat radiation characteristics. It may be a cap material made of the above material, a structure in which the element is molded with resin, or a bare chip structure in which the element is directly exposed.

A rubber sheet 8 is mounted on the upper surface of the Cu cap 7, and when the casings 5 and 6 are fastened with the screws 9, as shown in FIG.
While heating in an environment set at a temperature of 0 ° C. or lower, the rubber sheets 8 were compression-mounted by fastening the casings 5 and 6 with screws 9.

Immediately after the compression mounting of the rubber sheet 8 in a room temperature environment as shown in FIG. 4, it was transferred to a heating furnace and heated and maintained at a temperature of 50 ° C. or more and 100 ° C. or less.

In this heating and holding step, the heating and holding may be performed under the above-mentioned heating temperature environment for at least 10 minutes, usually 15 to 20 minutes. I got it.

In electronic modules housed in a housing, in a communication system module, an optical component is often precisely positioned and fixed using an adhesive. Since the temperature exceeds the heat resistance temperature of the mechanism, the heat treatment temperature of 50 ° C.
In a heat dissipation structure using a rubber sheet assuming a high compression ratio without affecting the reliability of the module product as a whole under the heating environment of 0 ° C or less,
A mounting structure with a lower load can be realized. <Embodiment 2> FIG. 2 is a sectional view showing a second embodiment of the present invention. When a heat radiation path from the electronic component having the heating element 1 to the housing is considered, the effect of heat conduction from the region other than the device mounting region of the Cu cap 4 attached to the upper surface of the device to the housing via the rubber sheet 8 is as follows. It is very small, and the heat dissipation path via the Cu cap 4 in the element mounting area occupies most.

For this reason, in this embodiment, the mounting area of the rubber sheet material 8 is not limited to the entire surface of the Cu cap 4 but is limited to the area of the heating element 1 inside the Cu cap 4.
With. This greatly reduces the load on the housings 5 and 6 and the electronic components and the module substrate 3 for the same compression ratio while minimizing the influence on the heat radiation characteristics.

Further, as in the case of the first embodiment, a temperature of 50 ° C.
The housings 5 and 6 were assembled by fastening the screws 9 while being heated and held under an environment of 00 ° C. or less. Also, as in the first embodiment, immediately after assembling the housing in a room temperature environment in advance, 5
A method of heating and holding in an environment of 0 ° C. or more and 100 ° C. or less was also performed.

When the screws are fastened to the housing while holding the former by heating, the initial load generated at the time of assembling the housing can be suppressed lower than in the latter case, so that the stress can be alleviated in a shorter time. Has been achieved and the short TAT (Tu
rn Around Time). <Embodiment 3> FIG. 11 shows an embodiment including a high-speed communication module structure equipped with optical communication optical components. Figure (a)
1 is a plan view showing the appearance of a semiconductor device according to the present invention, and FIG. 1 (b) is a sectional view thereof.

The basic structure of the apparatus is the same as that of the first embodiment. However, in the optical communication module, a laser diode module (optical element) 11 having a built-in laser diode for performing electric / optical conversion is provided in the upper casing 5. Alternatively, it is fixedly installed on the back surface of the lower housing 6. In this embodiment, the optical element 1
1 shows a case where 1 is provided on the back surface of the lower housing 6.

In this type of semiconductor device, since the amount of heat generated is large, it is generally often mounted directly on the fin-side back surface of a high heat dissipation housing. The laser diode module 11 includes a light emitting element for converting and outputting an electric signal to an optical signal, but generally also includes a light receiving element for converting an optical signal to an electric signal.

In the case of a light emitting element, high-precision positioning is performed in order to converge an output optical signal on the optical fiber 12 with high efficiency. Accurate positioning is required in the same manner as the light emitting element.

In the case of a light emitting element, an electric signal is converted into an optical signal, and in the case of a light receiving element, an optical signal is converted into an electric signal.
Enables high-speed signal transmission.

At this time, in order to implement a heat radiation structure to the housings 5 and 6 via the rubber sheet 8 of the semiconductor package 2 having the heating element 1, a high load is applied to the housing to deform the housing itself. If this occurs, the relative positions of the laser diode module 11 and the optical fiber 12 will be shifted, and the efficiency of condensing the optical signal emitted from the laser diode on the optical fiber 12 will be significantly deteriorated, degrading the product performance.

Accordingly, the high heat dissipation structure of the semiconductor package 2 can be achieved by attaching the rubber sheet 8 to the housing with a low load by the method shown in the first embodiment and achieving a high heat radiation structure of the semiconductor package 2. Is an essential requirement.

According to the present invention, the rubber sheet 8
Even if it is compressed and mounted at 0%, it is heated and held, so that the load on the housing is reduced, and it is possible to suppress the deformation of the housing while exhibiting the heat radiation effect. It is possible to prevent a reduction in the efficiency of condensing the optical signal on the optical fiber 12, thereby realizing a highly reliable device.

FIG. 12 schematically shows the direction of the load (load) applied to the housing when the thermally conductive rubber sheet 8 is compression-mounted in FIG.

FIG. 13 is a block diagram showing an example of a circuit configuration of an optical transceiver LSI including the semiconductor package 2 and the laser diode module 11 housed in the housing of FIG.

The outline of the function of this block diagram will be described. The upper part in the figure shows an electric signal input from the left end in the MU.
The signal is input to the rightmost LD module (transmitting unit) through an X circuit (multiplexing circuit), the input electric signal is converted into an optical signal by the LD module, and output as an optical signal from the rightmost end through an optical fiber (not shown). Is what you do.

On the other hand, the lower part in the figure converts the optical signal input from the right end through an optical fiber (not shown) into an electric signal by a PD module (reception unit), and at the same time through an amplifier to a DEMUX circuit (separation circuit) on the left end. Input and output to the outside.

That is, the MUX circuit (multiplexing circuit) and DEMUX circuit (separation circuit) on the left side of the optical transceiver LSI block correspond to the semiconductor package 2 in FIG.
The LD module and PD module on the right side
(Laser diode module).

In this apparatus, for example, 622 Mb
/ S data is input to the MUX circuit (multiplexing circuit), the optical output from the LD module (transmission unit) is 10 Gb
/ S data was output.

FIG. 14A is a schematic cross-sectional view illustrating the heat radiation structure of the semiconductor device (optical transceiver module) shown in FIG. FIG. 14 (b) and FIG. 14 (c)
Are partial enlarged views of the semiconductor package 2, respectively.
In FIG. 14B, the gap between the heating element 1 (transceiver LSI) and the metal cap 7 is filled with a heat conductive resin (thermosetting resin), and the BGA solder bumps 4 between the semiconductor package substrate 21 and the heating element 1 are formed. The surrounding gap is filled with an underfill resin having good thermal conductivity.

In the case of FIG. 14C, gold bumps are filled in place of the BGA solder bumps 4 and anisotropic conductive resin (non-conductive resin) is filled in place of the underfill resin. Consideration is given not only to the heat dissipation from 7 to the upper housing 5 side, but also to the module board 3 side and the lower housing side. <Embodiment 4> FIG. 15 is a sectional view of another embodiment including a module structure for high-speed communication on which optical components for optical communication are mounted. This example is basically the same as the structure shown in FIG. 11 of the third embodiment, except that the radiation fin 10 is provided on the lower housing 6 side. That is, the radiation fin 10
Is provided in the lower housing 6 on the side where the laser diode 11 is installed, so that the heat radiation effect of the laser diode 11 that generates a large amount of heat is enhanced. <Embodiment 5> FIG. 16 is a cross-sectional view of another embodiment including a high-speed communication module structure equipped with an optical communication optical component having a higher heat radiation effect than Embodiment 4 shown in FIG. is there. In this example, the heat conductive rubber sheet 8 is compressed into the gap between the laser diode 11 and the upper housing 5 in the same manner as the semiconductor package 2 so that the heat of the laser diode 11 is further radiated to the upper housing 5 side. I attached it. As a result, the laser diode 11, which generates a large amount of heat, is connected to both the upper and lower housings 5, 6.
The heat is dissipated from the radiator, further enhancing the heat dissipation effect. <Embodiment 6> FIG. 17A is a cross-sectional view of another embodiment including a high-speed communication module structure equipped with optical communication optical components. Basically, the fourth embodiment shown in FIG.
Has the same structure as that of the semiconductor package 2, but uses a bare chip as the heating element 1 in place of the semiconductor package 2 on the module substrate 3,
The difference is that they are directly connected via the solder bumps 4 and the underfill resin is filled around the solder bumps 4. Thus, heat from the bare chip 1 can be effectively radiated from the upper and lower housings 5 and 6.
FIG. 17B is a partially enlarged view schematically showing a heat dissipation path of the flip chip of the device shown in FIG. 17A.

FIG. 17C shows a heat radiation path in the case of the conventional wire bonding shown as a comparative example. <Embodiment 7> FIG. 18 is a sectional view of another embodiment including a high-speed communication module structure equipped with optical communication optical components. Basically, the structure is the same as that of the sixth embodiment shown in FIG. 17 (a). However, in this embodiment, the heating element 1 is composed of a multi-chip in which a plurality of bare chips having different heights are mixed on a module substrate 2. Is different. When a plurality of heating elements 1 having such height differences in height are mounted on the module substrate 2, the low-load heat radiation method of the present invention is extremely effective.

[0079]

As described in detail above, the intended object of realizing a semiconductor device having a highly efficient heat dissipation, low cost, and highly reliable heat dissipation mounting structure can be achieved by the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a sectional process view showing an example of the manufacturing method of the present invention.

FIG. 4 is a sectional process view showing another example of the manufacturing method of the present invention.

FIG. 5 is a cross-sectional view showing an experimental method for measuring mechanical properties of a rubber sheet for explaining the principle of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between a compression ratio and a compression load of a rubber sheet.

FIG. 7 is a graph showing stress relaxation characteristics of a rubber sheet at room temperature.

FIG. 8 is a graph showing stress relaxation characteristics of a rubber sheet at 85 ° C. for explaining the principle of the present invention.

FIGS. 9A and 9B are a cross-sectional view and a plan view illustrating a method of measuring a housing load when a rubber sheet is attached, illustrating the principle of the present invention.

FIG. 10 is a characteristic diagram showing a measurement result of a housing load when a rubber sheet is attached, explaining the principle of the present invention.

FIG. 11 is a plan view and a cross-sectional view of a semiconductor device according to a third embodiment of the present invention.

FIG. 12 is a cross-sectional view of a semiconductor device schematically illustrating a direction of a load applied to a housing when a rubber sheet is compression-mounted in a third embodiment of the present invention.

FIG. 13 is a circuit block diagram of an optical transceiver LSI including a semiconductor package and a laser diode module housed in a housing in a third embodiment of the present invention.

FIG. 14 is a cross-sectional view illustrating a heat dissipation structure of a semiconductor device shown as a third embodiment of the present invention.

FIG. 15 is a sectional view of a semiconductor device according to a fourth embodiment of the present invention.

FIG. 16 is a sectional view of a semiconductor device according to a fifth embodiment of the present invention.

FIG. 17 is a sectional view of a semiconductor device according to a sixth embodiment of the present invention.

FIG. 18 is a sectional view of a semiconductor device according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heating element, 2 ... Semiconductor package, 3 ... Module board, 3a ... Installation hole of module board, 4 ... Solder bump 5 ... Upper housing, 5a ... Projection part of upper housing, 6 ... Lower housing, 6a ... projecting part of the lower housing, 7: metal cap (Cu cap), 8: heat conductive rubber sheet, 9: screw (fastening part), 10: heat radiation fin, 11: laser diode module, 12: optical fiber, 14 ... Strain gauge, 21 ... Semiconductor package board, 100 ... Semiconductor module,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kikuchi 6-16-16 Shinmachi, Ome-shi, Tokyo Inside the Device Development Center, Hitachi, Ltd. (72) Inventor Tomoaki Nose 6-16 Shinmachi, Ome-shi, Tokyo (3) Inside the Device Development Center, Hitachi, Ltd. (72) Inventor Takashi Kubo 502, Kunitachi-cho, Tsuchiura-shi, Ibaraki Pref. Inside Machinery Research Laboratories, Ltd. Hitachi, Ltd. Communications Division (72) Inventor Kenji Yoshimoto 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Communications Division, Hitachi, Ltd. 5F036 AA01 BA23 BB21 BC03 5F041 AA33 DA12 DA19 EE08 5F073 AB28 BA01 EA29 FA25 FA30 5F088 BA11 BB01 JA03 JA14 JA20

Claims (17)

[Claims] A semiconductor device electrically connected to and mounted on the wiring substrate via an electrode connecting conductive material; a housing for housing the wiring substrate and the semiconductor device; A semiconductor device provided with a heat conductor that is disposed in a gap between a semiconductor device and a housing and conducts heat of the semiconductor device to the housing, wherein the housing has an upper housing having openings with each other. A semiconductor device mounted on the wiring board and having a structure in which one opening is fitted into the other opening, and a semiconductor device mounted on the wiring board is provided at a peripheral edge of the housing. The heat conductor is softer than the conductive material for electrode connection at room temperature, and the compression load when heated in a temperature range higher than room temperature is at room temperature. Made of a thermally conductive elastic material smaller than the compressive load of A semiconductor device characterized by being heated and compressed mounted at the temperature range in the gap between the semiconductor device and the housing. 2. A wiring board, a semiconductor device electrically connected and mounted on the wiring board via a conductive material for electrode connection, a housing for housing the wiring board and the semiconductor device, A semiconductor device provided with a heat conductor that is disposed in a gap between a semiconductor device and a housing and conducts heat of the semiconductor device to the housing, wherein the housing has an upper housing having openings with each other. A semiconductor device mounted on the wiring board and having a structure in which one opening is fitted into the other opening, and a semiconductor device mounted on the wiring board is provided at a peripheral edge of the housing. And a fitting / compression means for housing and holding the inside of the housing, and the housing inner wall includes an electrode terminal electrically connected to the semiconductor device on the wiring board, and an optical terminal connected to the optical fiber. Holding the optical element, wherein the thermal conductor is at room temperature Softer than the conductive material for electrode connection, and, when heated in a temperature range higher than room temperature, a compressive load is made of a thermally conductive elastic body smaller than a compressive load at room temperature, and the gap between the semiconductor device and the housing is A semiconductor device, which is heated in a temperature range and mounted under compression. A semiconductor package electrically connected to and mounted on the module substrate via a first solder; a housing accommodating the module substrate and the semiconductor package; a semiconductor; A semiconductor device comprising a heat conductor disposed in a gap between a package and a case and conducting heat of the semiconductor package to the case, wherein the case has an upper case and a lower portion having openings. And the housing has a structure in which one opening fits into the other opening, and a peripheral portion of the housing has a semiconductor package and a heat conductor mounted on the module substrate. Having a fitting crimping means for storing and holding the
In the semiconductor package, a semiconductor element is electrically connected to and mounted on a package substrate via a second solder. The heat conductor is softer at room temperature than the first and second solders and at room temperature. A compressive load when heated in a temperature range lower than a higher solder reflow temperature is made of an elastic body smaller than a compressive load at room temperature, and is heated and compressed in a gap between the semiconductor package and the housing in the temperature range. A semiconductor device. 4. A module substrate, a semiconductor package electrically connected and mounted on the module substrate via a first solder, a housing for accommodating the module substrate and the semiconductor package, and the semiconductor A semiconductor device comprising a heat conductor disposed in a gap between a package and a case and conducting heat of the semiconductor package to the case, wherein the case has an upper case and a lower portion having openings. And a housing having a structure in which one opening fits into the other opening, and a peripheral portion of the housing includes a semiconductor package and a heat conductor mounted on the module substrate. Having a fitting and crimping means for storing and holding the
In the semiconductor package, a semiconductor element is electrically connected to and mounted on a package substrate via a second solder, and on the inner wall of the housing, an electrode electrically connected to a semiconductor package electrode on the module substrate Holding an optical element having a terminal and an optical terminal connected to an optical fiber, wherein the heat conductor is softer than the first or second solder at room temperature, and higher than room temperature and higher than a solder reflow temperature. A semiconductor characterized in that a compressive load when heated in a low temperature range is made of an elastic body that is smaller than a compressive load at normal temperature, and is heated and compressed in a gap between the semiconductor package and the housing in the temperature range. apparatus. 5. A wiring board, a plurality of semiconductor devices electrically connected and mounted on the wiring substrate via an electrode-connecting conductive material, and a housing for accommodating the wiring substrate and the plurality of semiconductor devices. A body, and are collectively arranged in a gap between the plurality of semiconductor devices and the housing;
A semiconductor device comprising: a heat conductor that conducts heat of the plurality of semiconductor devices to a housing; wherein the housing is divided into an upper housing and a lower housing having an opening, and One opening has a structure that fits into the other opening, and a plurality of semiconductor devices mounted on the wiring board and a heat conductor are housed and held in the housing at the periphery of the housing. The heat conductor is softer than the conductive material for electrode connection at room temperature, and has a heat conductivity smaller than a compression load at room temperature when heated in a temperature range higher than room temperature. A semiconductor device comprising an elastic body, which is heated and compressed in a gap between the plurality of semiconductor devices and a housing in the temperature range. 6. The thermal conductor has a thermal conductivity of 1.0 to 7.0.
It is composed of a thermally conductive elastic material having a W / m · K, an elastic modulus at room temperature of 0.5 to 5.0 Pa, and a compressive load when heated in a temperature range higher than room temperature is smaller than a compressive load at room temperature. ,
6. The semiconductor device according to claim 1, wherein the semiconductor device is heated and compressed in the temperature range in a gap between the semiconductor device and the housing.
The semiconductor device according to any one of the above. 7. When the deformation resistance is expressed by a load required per unit compressibility, the deformation resistance at 100 ° C. is 1/3 to 1/1/30 ° C. 6. The semiconductor device according to claim 1, wherein the semiconductor device is made of a heat conductor made of a rubber material. 8. The thermal conductor according to claim 1, wherein a thickness of a first portion in contact with the semiconductor device or the semiconductor package is t.
1. The thickness t1 is 40 to 70% of t2, where t2 is the thickness of the second portion that does not contact the semiconductor device or the semiconductor package around the semiconductor device or the semiconductor package. The semiconductor device according to any one of the above. 9. A fitting press-fitting means for housing and holding the semiconductor device or the semiconductor package and the heat conductor in a housing is tightened by a screw mechanism provided at a peripheral portion between the upper housing and the lower housing. 6. The semiconductor device according to claim 1, wherein the semiconductor device is constituted by a means. 10. The semiconductor device according to claim 1, wherein the semiconductor device or the semiconductor package has a high-speed communication element mounted thereon. 11. A step of electrically connecting and mounting a semiconductor device having a heating element on a wiring board via a conductive material for electrode connection, and mounting the wiring board on which the semiconductor device is mounted in an upper housing and a lower housing. Accommodating in a housing divided into a body and a body, wherein the step of housing a wiring board on which the semiconductor device is mounted in the housing includes: The heat conductive elastic body is inserted into the gap between the housing and the upper housing and the lower housing by fitting and crimping, so that the heat conductive elastic body is compressed and mounted in the gap between the semiconductor device and the housing. And a step of clamping and fixing the wiring board between an upper housing and a lower housing, wherein the heat conductive elastic body is softer than the conductive material for electrode connection at room temperature, and is heated in a temperature range higher than room temperature. Compressive load at normal temperature Made small sheet thermally conductive elastomer piece from compressive load, as a step after the step of accommodating the wiring board in a housing,
A method of manufacturing a semiconductor device, further comprising a step of heating and holding a housing in which the wiring board is stored in a temperature environment of 50 to 100 ° C. 12. A step of electrically connecting and mounting a semiconductor device having a heating element on a wiring substrate via a conductive material for connecting electrodes, and connecting the wiring substrate on which the semiconductor device is mounted to an upper case and a lower case. Accommodating in a housing divided into a body and a body, wherein the step of housing a wiring board on which the semiconductor device is mounted in the housing includes: The heat conductive elastic body is inserted into the gap between the housing and the upper housing and the lower housing by fitting and crimping, so that the heat conductive elastic body is compressed and mounted in the gap between the semiconductor device and the housing. And holding and fixing the wiring board between the upper housing and the lower housing, and applying heat to the heat conductive elastic body at 50 to 100 ° C. while the compressive load is applied.
Step of heating and holding under a temperature environment, the heat conductive elastic body is softer than the conductive material for electrode connection at room temperature, and the compression load when heated in a temperature range higher than room temperature is at room temperature. A method of manufacturing a semiconductor device, comprising a sheet-like heat conductive elastic body having a smaller compressive load, wherein heat of the semiconductor device is conducted to the housing via the heat conductive elastic body. 13. A step of electrically connecting and mounting a semiconductor device having a heating element on a wiring substrate via a conductive material for electrode connection; and mounting the wiring substrate on which the semiconductor device is mounted in an upper housing and a lower housing. Storing the wiring board on which the semiconductor device is mounted in the housing, the method comprising: housing the wiring board on which the semiconductor device is mounted in the housing. A step of previously disposing an optical element having an electrode terminal electrically connected to the semiconductor device and an optical terminal connected to the optical fiber on the inner wall of the housing; and The heat conductive elastic body is inserted into the gap, and the upper housing and the lower housing are fitted and press-fitted, so that the heat conductive elastic body is compression-mounted in the gap between the semiconductor device and the housing, and The wiring board is sandwiched between the upper housing and the lower housing. The step of holding and fixing, wherein the heat conductive elastic body is softer than the conductive material for electrode connection at room temperature, and a compression load when heated in a temperature range higher than room temperature is smaller than a compression load at room temperature. Made of a heat conductive elastic material in a shape, as a post-process of housing the wiring board in a housing,
A method of manufacturing a semiconductor device, further comprising a step of heating and holding a housing in which the wiring board is stored in a temperature environment of 50 to 100 ° C. 14. A step of electrically connecting and mounting a semiconductor device having a heating element on a wiring substrate via a conductive material for connecting electrodes, and mounting the wiring substrate on which the semiconductor device is mounted in an upper case and a lower case. Storing the wiring board on which the semiconductor device is mounted in the housing, the method comprising: housing the wiring board on which the semiconductor device is mounted in the housing. A step of previously disposing an optical element having an electrode terminal electrically connected to the semiconductor device and an optical terminal connected to the optical fiber on the inner wall of the housing; and The heat conductive elastic body is inserted into the gap, and the upper housing and the lower housing are fitted and press-fitted, so that the heat conductive elastic body is compression-mounted in the gap between the semiconductor device and the housing, and The wiring board is sandwiched between the upper housing and the lower housing. Holding and fixing the heat conductive elastic body in a state where the compressive load is applied.
Heating at a temperature environment of 100 ° C., wherein the heat conductive elastic body is softer than the conductive material for electrode connection at room temperature, and has a compressive load when heated in a temperature range higher than room temperature. A method of manufacturing a semiconductor device, comprising: a sheet-like heat conductive elastic body smaller than a compression load at step (a), wherein heat of the semiconductor device is conducted to the housing via the heat conductive elastic body. . 15. The heat conductive elastic body has a heat conductivity of 1.
0 to 7.0 W / m · K, and the elastic modulus at room temperature is 0.5 to
15. The method for manufacturing a semiconductor device according to claim 11, wherein the pressure is 5.0 MPa. 16. The heat conductive elastic body has a deformation resistance at 100 ° C. which is 1/3 to a deformation resistance at 30 ° C. when the deformation resistance is represented by a load required per unit compressibility. 1
2. The rubber material according to claim 1, which is made of a rubber material.
15. The method for manufacturing a semiconductor device according to any one of 1 to 14. 17. The method according to claim 17, wherein said heat conductive elastic body is compressed and mounted in a gap between said semiconductor device and said housing, and said wiring board is sandwiched and fixed between an upper housing and a lower housing. Assuming that the thickness of the first portion where the elastic body contacts the semiconductor device is t1 and the thickness of the surrounding second portion that does not contact the semiconductor device is t2, the thickness t1 is 4 of t2.
The method of manufacturing a semiconductor device according to claim 11, wherein the semiconductor device is compression-mounted so as to be 0 to 70%.