JP2001244390A - Package for semiconductor device and mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain strong and stable electrical connection for a long period even in the case where a package for semiconductor device provided with the lid for heat radiation is mounted in the outside circuit board. SOLUTION: In this solution, the package B for semiconductor device is structured by means of loading the semiconductor device A provided with a connecting electrode 8 on the surface of the insulating board 1 whereupon a metalization wiring layer 2 is formed on the surface or inside, by means of brazing both the metalization wiring layer 2 and the connecting electrode 8 of the semiconductor device A, by means of arranging the high heat conductive closure 13 with the leg 13a for covering the semiconductor device A, by means of adhering and stabilizing the leg 13a to the surface of the insulating board 1, and by means of adhering a part of the high heat conductive closure 13 to the topside of the semiconductor device A. In this package B for semiconductor device, the heat expansion coefficient of the insulating board 1 is from 8 to 20 ppm/ deg.C in the temperature from 40 to 150 deg.C, and the leg part 12a of the high heat conductive closure 12 is installed and stabilized to the surface of the insulating board 1 by the bonding agent 13 which is under 1 GPa in Young's modulus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for a semiconductor device, and more particularly to a high thermal conductive cover for surface mounting a semiconductor device on a large-sized wiring board by brazing and dissipating heat generated from the semiconductor device. TECHNICAL FIELD The present invention relates to a semiconductor device package having a body and excellent in use durability and reliability and a mounting structure thereof.

[0002]

2. Description of the Related Art Conventionally, a wiring board has a structure in which a metallized wiring layer is provided on the surface or inside of an insulating substrate. A typical example of the wiring board is a semiconductor element housing package for housing a semiconductor element, especially a semiconductor integrated circuit element such as an LSI (large-scale integrated circuit element). A plurality of metallized wiring layers made of a high melting point metal powder such as tungsten or molybdenum are provided on the surface and inside, and are electrically connected to a semiconductor element mounted thereon. In general, as the degree of integration of a semiconductor device increases, the number of electrodes formed on the semiconductor device also increases, and accordingly, the number of terminals in a semiconductor storage package for storing the same increases.

If the installation density of the corresponding connection terminals is not changed with an increase in the number of electrodes, the dimensions of the package itself must be increased. However, recently, there has been a strong demand for downsizing of the package. There is a limit in increasing the size.

Therefore, the installation density of the connection terminals in the package is unavoidable, but it is difficult for the conventional wire bonding type connection method to sufficiently cope with the recent tendency of highly integrated semiconductor devices. And is approaching its limits.

For this reason, recently, the connection between the package and the semiconductor element is directly brazed to the connection electrode on the lower surface of the semiconductor element and the connection terminal of the package by a wire bonding method in which the periphery of the semiconductor element is connected to the connection terminal wire of the package. We are moving to flip chip mounting.

In connection by the flip-chip mounting, a filler called an underfill material composed of a composite of a thermosetting resin and a spherical filler is injected between a semiconductor element and an insulating substrate of a package, and then cured. It is often performed to mechanically reinforce the mounting part of a semiconductor element.

[0007] Further, with the recent increase in heat generation of semiconductor elements, semiconductor element storage packages provided with heat radiation fins tend to be often used to radiate heat generated from the semiconductor elements. In view of this, there has been proposed a package for housing a semiconductor element having a structure in which a highly heat-conductive lid called a lid is attached to the surface of a substrate, and further, a radiation fin is attached to the upper surface of the lid (see Japanese Patent Application Laid-Open No. 8-264688).

According to this proposal, there is provided a lid made of alumina or Kovar made of a material having the same thermal expansion coefficient as that of a package base made of alumina ceramic, and the lid generates heat generated from electronic components mounted on the surface of the base. Through the heat dissipation fins.

On the other hand, such a package is mounted on an external circuit board by mounting a so-called ball grid array (BGA) on the back surface of the package on which the semiconductor element is mounted.
As shown in the above, a connection terminal formed of a solder ball is attached, and the connection terminal is electrically connected to an electrode on the surface of the external circuit board by a brazing material via the connection terminal. In the external circuit board, the insulating base material of the printed board is mainly made of an organic material or a composite material of an organic material and an inorganic material, such as a glass-epoxy resin composite material.

However, when ceramics such as alumina and mullite which are conventionally used as an insulating substrate of a package in which connection terminals such as a BGA are formed at a high density are used, they are mounted on an external circuit board such as the above-mentioned printed circuit board. In this case, heat generated during operation of the semiconductor element is repeatedly applied to both the insulating substrate and the external circuit board, and a thermal stress is generated due to a difference in thermal expansion coefficient between the external circuit board and the insulating substrate. There has been a problem that the wiring board cannot be stably maintained on the external circuit board for a long period of time because the wiring board is peeled off from the insulating substrate or cracks occur in the connection terminals.

Therefore, the present applicant has changed the conventional ceramics, such as alumina and mullite, and formed the insulating substrate with a high thermal expansion ceramic material, so that the thermal expansion between the insulating substrate of the package and the insulating base material of the external circuit substrate was improved. It has been proposed to improve the connection reliability by reducing the difference (Japanese Patent Application Laid-Open No. Hei 8-279574, Japanese Patent Application No. Hei 8-3220).
No. 38).

[0012]

However, a lid made of the same material having the same coefficient of thermal expansion as that of the insulating substrate as disclosed in JP-A-8-264688 is used by using the above-mentioned high thermal expansion ceramic material as an insulating substrate. When the mounted semiconductor element storage package is surface-mounted on an external circuit board such as the printed circuit board, when a heat cycle is applied by stopping the operation of the semiconductor element, a high thermal expansion glass ceramic is used for the insulating substrate, especially in a cooling process. However, since there is a difference in thermal expansion with the external circuit board, the insulating substrate tries to bend so that the mounting surface with the external circuit board becomes convex, but the insulating substrate is firmly joined to the opposite side to the mounting surface The insulating substrate can hardly bend because it is restrained by the provided lid. As a result, the mounting surface of the external circuit board with the insulating substrate is bent so as to be convex.

This bending acts in the direction of peeling off the connecting portions of the connection terminals between the wiring board and the external circuit board, which are located on the outer periphery. For example, the wiring board cannot be stably maintained on the external circuit board for a long time.

Therefore, according to the present invention, even when a package for a semiconductor device having the above-mentioned lid is mounted on an external circuit board, a long-term reliability which can maintain a strong and stable electric connection for a long period of time. It is an object of the present invention to provide a package for a semiconductor element having remarkably excellent performance and a mounting structure thereof.

[0015]

Means for Solving the Problems The present inventors place a semiconductor element having connection electrodes on a surface of an insulating substrate having a metallized wiring layer formed on the surface or inside thereof, and connect the metallized wiring layer to the metallized wiring layer. A soldering electrode and a connection electrode of a semiconductor element are formed, and a high thermal conductive lid having legs is arranged so as to cover the semiconductor element, and the legs are bonded and fixed to the surface of the insulating substrate. As a result of various studies on a semiconductor element package in which a part of the high thermal conductive lid is bonded to the upper surface of the semiconductor element, the thermal expansion coefficient of the insulating substrate at 40 to 150 ° C. is 8 to 2
0 ppm / ° C., and the high thermal conductive lid is attached and fixed to the surface of the insulating substrate with a low Young's modulus adhesive having a Young's modulus of 1 GPa or less. It has been found that a stable electrical connection can be maintained for a long time.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail. FIG. 1 is a schematic sectional view showing an example of a semiconductor device package of the present invention and an example of a mounting structure thereof. FIG. 1 shows an example of a BGA type package having connection terminals formed of ball terminals as a package in the present invention, wherein A is a semiconductor element, B is a BGA type package, and C is an external circuit board.

In FIG. 1, a package B has a metallized wiring layer 2 formed on the surface and inside of a ceramic insulating substrate 1, and a connection pad 3 is formed on the bottom surface of the package B. Is electrically connected to the metallized wiring layer 2 disposed on the surface and inside. In the BGA type package of this figure, ball-shaped connection terminals 4 are connected to the connection pads 3 by soldering.

On the other hand, the external circuit board C is made of a so-called printed board, and Cu, Au, Al, Al, Al, Al, Al, and Al are formed on the surface of a resin substrate 5 made of a material containing an organic resin such as a glass-epoxy resin or a glass-polyimide resin composite material. Ni, Pb-
A connection conductor 6 made of a metal such as Sn is adhered and formed.

The connection conductor 6 of the external circuit board C
The package B is mounted on the surface of the external circuit board C by connecting the ball-shaped connection terminals 4 of the package B with solder 7 or the like.

The insulating substrate 1 constituting the package B is
The coefficient of thermal expansion at 40 ° C to 150 ° C is 8 to 20 pp
It is composed of m / C ceramics. This is necessary to obtain long-term connection reliability with the external circuit board C having the resin substrate 5 containing an organic resin. Therefore, when the coefficient of thermal expansion of the insulating substrate 1 is smaller than 8 ppm / ° C. or larger than 20 ppm / ° C., the difference in thermal expansion with the external circuit board C increases, and the connection reliability is increased due to the stress caused by the difference in thermal expansion. This is because the property is impaired.

A plurality of connection electrodes 8 are provided on the bottom surface of the semiconductor element A mounted on the surface of the package B, and the metallized wiring layer 2 on the surface of the package B and connection terminals made of a brazing material such as solder. The underfill material 10 is made of a thermosetting resin, and is electrically reinforced.

According to the present invention, a high thermal conductive lid (hereinafter, simply referred to as a lid) 12 is adhered to the surface opposite to the surface on which the semiconductor element A is mounted on the package B by a high thermal conductive resin. I have. Further, the lid 12 is the lid 12
Of the adhesive 13 on the surface of the insulating substrate 1
It is attached and fixed by.

In such a semiconductor device housing package structure, if the Young's modulus of the adhesive 13 for attaching the leg 12a of the lid 12 to the insulating substrate 1 is high, the insulating substrate 1 and the lid 12 may be in contact with each other. The adhesion is strong, the binding force is increased, and in the temperature cycle test, the external circuit board C bends due to the difference in thermal expansion coefficient between the insulating substrate 1 and the external circuit board C. As a result of the restraint, the insulating substrate 1 cannot bend, stress is concentrated on the connection portion between the circuit substrate C and the insulating substrate 1, and the connection between the insulating substrate 1 and the external circuit substrate C becomes unstable. Become.

Therefore, according to the present invention, the stress of the lid 12 applied to the insulating substrate 1 of the package B is reduced by reducing the Young's modulus of the adhesive 13 to 1 GPa or less, especially 0.5 GPa or less. It is possible to reduce the stress acting on the connection between the insulating substrate 1 and the external circuit board C.

The adhesive 13 is used to attach the lid 12 to the insulating substrate 1.
It is desired to have a strong adhesive property in the role of bonding to the substrate. Specifically, it is desirable to contain at least one thermosetting resin selected from the group consisting of an epoxy-based resin, a silicone-based resin, a melamine-based resin, and an ester-based resin. It may be a composite formed with at least one inorganic filler selected from the group consisting of cloth, spherical silica, and alumina.

On the other hand, the lid 12 is desired to have high thermal conductivity in order to radiate heat generated by the semiconductor element to the outside. Specifically, Al-SiC composite material (AlSiC), Cu-W alloy, Cu, Fe-Ni-C
One of o alloy, Cu-Cr alloy, and Al can be cited, and it is conveniently used depending on the amount of heat radiation and whether or not the heat radiation fins 15 are attached.

In order to reduce the stress caused by the difference in thermal expansion between the package structure for mounting a semiconductor element and the mounting structure, the lid 12 is formed of a material having a lower coefficient of thermal expansion than the insulating substrate 1. Insulating substrate 1
<It is desirable to combine the resin substrates 5 so that the coefficient of thermal expansion increases in this order.

As a highly heat conductive adhesive for connecting the upper surface of the semiconductor element and the lid 12, an epoxy resin is preferable.

Further, according to the present invention, the lid 12 is provided with the legs 12a for mounting to the insulating substrate 1, and the mounting position of the legs 12a to the insulating substrate 1 is shown in FIG. As shown in the plan view of FIG. 2, of the plurality of connection terminals 4 arranged on the back surface of the insulating substrate 1, a region inside the connection terminal 4 a provided on the outermost side, more specifically, located on the outermost side. It is preferable that the inner side be inside a region surrounded by a line segment x connecting the connecting terminals 4a to be connected.

This is because the maximum stress is generated below the leg 12a of the lid 12 and the maximum stress between the insulating substrate 1 and the external wiring substrate 5 is generated at the connection terminal 4a. By attaching the attachment portions of the twelve legs 12a inside the line segment X, it is possible to disperse the stress by avoiding the concentration of these stresses.

The insulating substrate 1 according to the present invention, in which the package B has a coefficient of thermal expansion of 8 to 20 ppm / ° C., is made of, for example, BaO of 5 to 60 as proposed by the present inventors.
Using a glass with low softening point and high thermal expansion contained in a proportion of weight%, it has a high thermal expansion property obtained by mixing with a predetermined filler and firing, and at the same time as a low resistance metal such as Cu at a low temperature of 1000 ° C or less. It consists of a sinterable glass ceramic sintered body. In addition, as described in the specification of Japanese Patent Application No. 8-322038, for example, lithium silicate glass,
Enstatite, forsterite, forsterite and SiO ₂ filler, MgO, ZrO ₂ , glass components such as PbO-based glass, ZnO-based glass, BaO-based glass,
It is formed of a composite material of various ceramic fillers such as petalite.

For example, a slurry is prepared by appropriately adding an organic binder to a mixed powder obtained by mixing 20 to 90% by volume of the glass and 80 to 10% by volume of the filler, and the slurry is formed into a sheet. Thereafter, a conductor paste containing a low-resistance metal such as Cu, Au, or Ag is printed and applied to the surface of the sheet-shaped molded body. If desired, a through hole is formed at a predetermined position of the sheet-like molded body by punching, laser, or the like, and the conductive paste is filled in the through hole. Then, the sheet-shaped molded body is laminated and pressed to produce a laminated body, which is then fired at 800 to 1000 ° C. in the air or a nitrogen atmosphere to produce an insulating substrate.

Also, a low-resistance metal film is formed on the surface of the insulating substrate by a so-called thin film method, and an insulating substrate having fine wiring can be manufactured by photolithography using a positive photoresist.

As shown in FIG. 1, an adhesive 14 such as an epoxy resin may be provided on the upper surface of the lid 12 if desired.
The heat generated from the semiconductor element A can be more efficiently radiated by attaching the radiating fins 15 by using.

[0035]

EXAMPLES For various ceramic materials shown in Table 1, 5
After preparing a ceramic sintered body having a shape of mm × 4 mm × 40 mm, the coefficient of thermal expansion of each sintered body was measured. Table 1 shows the measured values.

[0036]

[Table 1]

Further, using the various ceramic sintered bodies shown in Table 1 as an insulating substrate, a metallized wiring layer made of copper and a through-hole conductor are formed thereon, and the ceramic sintered body is connected to the through-hole conductor on the upper surface of the package. A large number of electrode pads to be connected to the semiconductor element are formed, and further, on the bottom surface, connection pads for connection to an external circuit board are formed, and a metallized wiring layer, through-hole conductors, electrode pads, connection pads, and an insulating substrate are formed. And 9 in a nitrogen atmosphere
A package was prepared by simultaneous firing at 50 ° C.

Then, 1444 ball-shaped connection terminals made of high melting point solder (Sn: Pb weight ratio = 10: 90) are connected to the connection pads on the bottom surface of the package with low melting point solder (S
n: Pb weight ratio = 63: 37) to produce a package. The prepared package had a length × width × thickness of 40 mm × 40 mm × 1 mm, and connection terminals were attached to a region of 38 mm × 38 mm on the back surface of the insulating substrate.

After the electrode pads are plated with Ni, a semiconductor element made of Si having a thermal expansion coefficient of 2.8 ppm / ° C. at 0 to 100 ° C. is prepared for the electrode pads. After the connection electrodes provided are connected by low-melting point solder and mounted, an underfill material (epoxy resin) is injected into the gap between the semiconductor element and the package, and heat-treated at 180 ° C. for 2 hours to be cured. Thus, the semiconductor element was fixed to the package.

On the other hand, a lid made of a high thermal conductor containing 30% by weight of Al with respect to SiC was prepared. This lid has a thermal expansion coefficient of 7 × 10 ⁻⁶ / 0 to 100 ° C.
° C and the Young's modulus was 300 GPa. Note that the planar size of the lid is 35 mm × 35 mm (narrower than the connection terminal attachment area).

Thereafter, a high thermal conductive resin (silicone resin) is applied to the upper surface of the semiconductor element mounted on the upper surface of the package, and further, the bonding shown in Table 2 is applied to the tip of the leg of the lid and the mounting portion of the insulating substrate. After applying the material, the lid was aligned and bonded, and cured at 150 ° C. and fixed.

At this time, the mounting positions of the legs of the lid to the insulating substrate were, as shown in FIG. 2, adhered and fixed to a region inside the connecting terminals located on the outermost side of the connecting terminal mounting portion on the back surface of the insulating substrate. .

A connection conductor made of copper foil was formed on the surface of a resin substrate having a thermal expansion coefficient of 20 ppm / ° C. at −40 to 125 ° C. made of a glass epoxy substrate. With respect to the printed circuit board, the ball-shaped connection terminals of the package,
It is positioned at 240 ° C. in a nitrogen atmosphere using low-melting-point solder at a temperature of 240 ° C. so as to be connected to the connection conductor of the printed circuit board.
The package was mounted on the surface of the printed circuit board by heat treatment for minutes.

(Temperature Cycle Test) The test sample was placed in a high-temperature bath controlled at -40 ° C. and 125 ° C. in an air atmosphere in a state in which the package was mounted on the printed circuit board surface as described above, and the test sample was subjected to 15 minutes / 15 minutes. Up to 2000 cycles were repeated with one cycle of holding. Then, the electrical resistance between the connection of the printed circuit board and the package is measured every 100 cycles, and the number of cycles until the electrical resistance changes is shown in Table 2.
It was shown to.

[0045]

[Table 2]

[0046]

[Table 3]

As is clear from Tables 2 and 3, when the Young's modulus of the adhesive between the insulating substrate and the lid according to the present invention is 1 GPa or less, the distance between the package and the printed circuit board in a thermal cycle test up to 2000 times is possible. No electrical resistance change was observed at all, and an extremely stable and good electrical connection was maintained.

Sample Nos. Other than the above 1-3, 8-10,
In 15 to 17, 22 to 24, and 29 to 31 (samples other than the present invention), a change in electric resistance was observed between the package and the printed circuit board in less than 2000 cycles of the thermal cycle test. Connection terminals peeled off from the insulating substrate, and cracks occurred in the connection portions.

[0049]

As described above, according to the present invention, by using an adhesive having a Young's modulus of 1 GPa or less as an adhesive for attaching the insulating substrate and the lid of the package, the package and the external circuit board can be connected to each other. Can reduce the stress acting on the connecting portion due to the difference in thermal expansion between the two. Thus, a connection failure between the package and the external circuit board does not occur, and a reliable and strong electrical connection can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a BGA type semiconductor element package and its mounting structure as one embodiment of a semiconductor element package of the present invention.

FIG. 2 is a plan view for explaining a mounting position of a lid in the package for housing a semiconductor element of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 metallized wiring layer 3 connection pad 4 connection terminal 5 resin substrate 6 wiring conductor 7 solder 8 connection electrode 9 connection terminal 10 underfill material 11 high heat conductive resin 12 high heat conductive lid 13 adhesive material 14 adhesive material 15 Heat radiation fin A Semiconductor element B Package C External circuit board

Claims (14)

[Claims] 1. A semiconductor device provided with a connection electrode on a surface of an insulating substrate having a metallized wiring layer formed on the surface or inside thereof, and the metallized wiring layer and the connection electrode of the semiconductor device are brazed. A high thermal conductive lid having legs is arranged so as to cover the semiconductor element, and the legs are adhesively fixed to the surface of the insulating substrate, and a part of the high thermal conductive lid is provided. A semiconductor device package formed by adhering to the upper surface of the semiconductor device,
The thermal expansion coefficient of the insulating substrate at 40 to 150 ° C. is 8
A package for a semiconductor element, wherein the leg of the high thermal conductive lid is fixed to the surface of the insulating substrate with an adhesive having a Young's modulus of 1 GPa or less. 2. A plurality of connection terminals which are electrically connected to the semiconductor element via the metallized wiring layer are attached to a back surface of the insulating substrate. 2. The semiconductor device package according to claim 1, wherein a leg portion of the high thermal conductive lid is attached to a surface of the insulating substrate in a region inside the outermost connection terminal attachment position. 3. The semiconductor device according to claim 1, wherein an upper surface of the semiconductor element is bonded to the high thermal conductive lid with a high thermal conductive adhesive.
A package for a semiconductor device according to claim 2. 4. The package for a semiconductor device according to claim 1, wherein a radiating fin is joined to an upper surface of the high thermal conductive lid. 5. The high thermal conductive lid is made of aluminum and sulfur.
The semiconductor device package according to any one of claims 1 to 4, wherein the package is made of a composite material with iC or Cu. 6. The package for a semiconductor device according to claim 1, wherein said insulating substrate is made of glass ceramic, and said metallized wiring layer is made of a conductor containing copper as a main component. . 7. The semiconductor device according to claim 1, wherein said semiconductor element is flip-chip mounted on a metallized wiring layer on a surface of said insulating substrate.
A package for a semiconductor device according to claim 6. 8. A semiconductor device provided with a connection electrode on a surface of an insulating substrate having a metallized wiring layer formed on the surface or inside thereof, and brazing the metallized wiring layer and the connection electrode of the semiconductor device. A high thermal conductive lid having legs is arranged so as to cover the semiconductor element, and the legs are adhesively fixed to the surface of the insulating substrate, and a part of the high thermal conductive lid is provided. A semiconductor element package having a connection terminal provided on the back surface of the insulating substrate and having a connection terminal electrically connected to the semiconductor element via the metallized wiring layer. A mounting structure formed on a surface of an external circuit board provided with a resin substrate containing: wherein the insulating substrate has a coefficient of thermal expansion at 40 to 150 ° C. of 8
Wherein the leg of the high thermal conductive lid is fixed to the surface of the insulating substrate with an adhesive having a Young's modulus of 1 GPa or less. . 9. A leg portion of the high thermal conductive lid is attached to the surface of the insulating substrate in a region inside the outermost connection terminal mounting position of the plurality of connection terminals when viewed in plan. The mounting structure of a package for a semiconductor device according to claim 8, wherein: 10. The semiconductor element package mounting structure according to claim 8, wherein an upper surface of said semiconductor element is bonded to said high heat conductive lid with a high heat conductive adhesive. 11. The mounting structure for a semiconductor element package according to claim 8, wherein a heat radiation fin is joined to an upper surface of said high thermal conductive lid. 12. The package structure for a semiconductor element package according to claim 8, wherein said high thermal conductive lid is made of a composite material of aluminum and SiC, or Cu. 13. The semiconductor device package according to claim 8, wherein said insulating substrate is made of glass ceramic, and said metallized wiring layer is made of a conductor containing copper as a main component. Mounting structure. 14. The package structure for a semiconductor element package according to claim 8, wherein said semiconductor element is flip-chip mounted on a metallized wiring layer on a surface of said insulating substrate.