JPH1154665A - Composite package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate bonding work of solder balls by mounting a semiconductor element on a ceramic substrate having a recess, bonding a resin board to the surface of the ceramic substrate and providing an opening corresponding to the recess. SOLUTION: The composite package comprises a resin board 2 and a ceramic substrate 1 bonded together wherein a recess for mounting a semiconductor chip 5 is made in the ceramic substrate 1 and an opening corresponding to the recess is made in the resin board 2. More specifically, the ceramic substrate 1 is provided with a cavity and boded with the resin board 2 having an opening at a part corresponding to the cavity. Subsequently a semiconductor chip 5 is mounted using a conductive adhesive 7 and wire bonded through a bonding wire before being sealed using a potting agent 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-terminal, narrow-pitch semiconductor device package, and more particularly to a semiconductor device composite package in which a ceramic substrate and a resin substrate or a film are bonded and bonded.

[0002]

2. Description of the Related Art Various types of packages, such as ceramics, resins, and metals, on which semiconductor chips such as LSIs are mounted, have been increased in density due to high integration, high speed, large power consumption, and large chips of LSIs. There is a tendency for higher speed and higher heat dissipation to be required. These semiconductor chips are also used for workstations, personal computers,
2. Description of the Related Art From industrial use such as computers to electronic devices such as portable devices, printers, copiers, cameras, televisions, and videos, the performance of semiconductor devices themselves has been improved. Packages that mount high-performance, high-integration-density LSI chips must be able to connect to the LSI chip with multiple terminals and a narrow pitch, have high wiring density, have good heat dissipation, and can handle high-speed signals. It is required that the number of input / output terminals of a package can be increased and the pitch can be reduced. Further, there is a need for a technique for producing a high-performance package satisfying these conditions at a low cost with a simple process and high reliability.

[0003] In order to enhance the function of a semiconductor element, three pillars of increasing the number of bits, increasing the capacity, and increasing the speed are the pillars. Among them, the demand for high speed has had a great influence on the package. This is because the number of input / output terminals (pins) to / from the semiconductor element is increased and data is processed in parallel to increase the speed. For this reason, multi-terminals (multi-pins) has become one proposition in packages. In addition, miniaturization of portable devices and miniaturization of packages for high-density mounting are also required. This demand is particularly great in the field of multimedia, amusement and communication equipment, which will greatly increase in the future. Various packages have been developed to meet these two needs of multi-pin and miniaturization. In order for the connection technology with semiconductor elements to function effectively, the package side must also have a narrow-pitch, multi-terminal inner lead, and the connection between the mounting board, such as a printed circuit board, and the package must also have a multi-terminal, narrow pitch It is necessary to do. Further, as described above, the package needs to handle high-speed signals due to the increase in the speed of the LSI, so that it is necessary to consider the electrical characteristics.

In order to satisfy the above-mentioned demands for a package having a plurality of terminals and a narrow pitch, a package structure for an LSI is made of a conventional pin insertion type or a QFP (Quad Flood Package). From surface mount type to BGA (Ball Grid Array)
Array) tend to migrate to packages.

In a conventional surface mount type package,
This is because limits to the multi-terminal and narrow pitch are becoming apparent in terms of terminal accuracy, lead-induced inductance, lead strength, and mounting accuracy. Also, the surface mount type has a disadvantage that the package must be increased in size as the number of terminals increases.

The BGA can reduce the inductance compared to the conventional package, and can correspond to the multilayer wiring structure of the package body at high speed, and is used for consumer products such as large computers, personal computers, and portable devices. Is spreading. The BGA has a package structure using a protrusion connection body (solder ball) made of solder as an input / output terminal of the package, and improves reflection delay of a high-speed signal due to inductance caused by pins and leads as described above. Is possible. Further, in addition to shortening the connection distance by the solder ball, it is easy to form a narrow pitch and multiple terminals by forming the solder ball, and the BGA is promising as an LSI package in the future. For example 0.9m
If a solder ball in m is used, a pitch of 1.27 mm
An SI package can be realized. In addition, the narrow pitch and the large number of terminals by the formation of solder balls reduce the package size itself, improve the mounting density on printed circuit boards, etc.
It can be expected to improve electrical characteristics by reducing the parasitic capacitance, inductance, resistance, etc. of the wiring, and to improve high-frequency characteristics by reducing the size of the package. On the other hand, from the viewpoint of the heat dissipation of the package, with the increase in the integration density and the speed of the LSI,
Power consumption is increasing and the amount of heat generated tends to increase year by year.
Moreover, in the computer, while the size of the main body has been reduced, the number of boards has been increasing, and the gap between the boards has been gradually narrowed.

[0007] For these reasons, the package itself is required to be thin and to have a structure and material excellent in heat dissipation. Ceramic packages are mainly used for high heat dissipation packages. Ceramics include aluminum nitride, silicon nitride, alumina, glass ceramics and the like, and these are properly used depending on the specifications such as the calorific value and high frequency characteristics. However, in a ceramic package, when mounted on a printed circuit board, the connection reliability (mounting reliability) of the solder ball portion, which is a connection portion, is low because the difference in thermal expansion coefficient between the package and the printed circuit board is large. Have a problem. This difference in thermal expansion can be caused by thermal history in the reflow soldering process when mounting the BGA package on a printed circuit board, or by a change in environmental temperature during normal use. Due to the large difference in thermal expansion from the printed circuit board, thermal stress concentrates on the solder balls with low mechanical strength, causing cracks in the solder balls and breaking the solder balls. There was a problem that reliability was reduced.

In view of this problem, in recent years, a composite package in which a resin substrate having a thermal expansion coefficient close to that of a printed substrate is bonded to a ceramic substrate with an adhesive or the like has been improved to some extent. That is, by forming a composite package in which a ceramic substrate having high thermal conductivity and a resin substrate having a wiring layer are electrically and mechanically bonded to each other, the thermal expansion coefficient of the resin substrate and the thermal expansion coefficient of the printed circuit board are substantially reduced. The structure makes use of the advantage of equality, the ease of fine wiring by lithography of the resin substrate, the advantage of low cost of the resin substrate, and the advantage of the high thermal conductivity characteristic of the ceramic substrate.

[0009]

FIG. 2 shows a state in which a semiconductor chip 5 is mounted on a conventional composite package for a semiconductor device, bonded with a bonding wire 6, and sealed with a potting agent 4 from above. In the composite package for a cavity-down type semiconductor device including the resin substrate 2 and the ceramic substrate 11 as shown in FIG. 2, in the flat ceramic substrate 11, the potting agent 4 used for chip sealing is removed from the surface of the resin substrate. Because of the protrusion, it is impossible to arrange the solder balls 3 for the terminals at predetermined positions and join them. FIG. 2 shows the resin substrate 2
Has a thickness of 0.15 mm. In this case, the height of the projection of the potting agent 4 is 0.6, although it depends on the thickness of the semiconductor chip.
It is about 0.8 mm, so that the screen printing of the solder paste for arranging and joining the solder balls 3 becomes impossible.

When the thickness of the resin substrate 2 is increased as shown in FIG. 3 to prevent the inconvenience of the structure shown in FIG.
Thermal resistance increases, which is contrary to the demand for high power consumption of semiconductor devices. FIG. 3 shows a composite package in which the thickness of the resin substrate 12 is 0.45 mm. As in FIG. 2, the semiconductor chip 5 is mounted, the bonding wire 6 is wire-bonded, the potting agent 4 is sealed, and the solder ball 3 is bonded to a predetermined position. When the thermal resistance of the composite package shown in FIG. 3 was measured, it was as large as 20 ° C./W, and the allowable power consumption was as low as about 2.5 W.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a composite package for a semiconductor device in which a solder ball is easily joined and heat dissipation is good.

It is another object of the present invention to provide a composite package for a semiconductor device in which a solder ball is easily joined and mounting reliability is high.

[0013]

In order to achieve the above object, a composite package according to the present invention has a ceramic substrate having a concave portion for mounting a semiconductor element, and an opening corresponding to the concave portion. And a resin substrate bonded to the surface.

According to the feature of the present invention, since a so-called cavity is provided in the semiconductor chip mounting portion of the ceramic substrate, the protrusion of the potting agent can be suppressed to a value lower than a predetermined value, and soldering can be easily performed. Ball joining becomes possible. The protrusion of the potting agent from the surface of the resin substrate (a film-like substrate having a thickness of about 0.08 to 0.3 mm) is preferably 0.2 mm or less. Also, since the thickness of the resin substrate can be reduced,
Low heat resistance and good heat dissipation. According to the experimental results of the present inventors, in the case of a cavity-down type composite package for a semiconductor device, the thermal resistance becomes a minimum value near a thickness of 0.6 mm as the thickness of the ceramic substrate is reduced, and is further reduced when the thickness is further reduced. Was found to increase.
Therefore, a ceramic substrate having a thickness of about 0.6 mm is preferable.
In order to make the thickness of the conductive adhesive for fixing the semiconductor chip to the ceramic substrate 0.05 mm and to make the projection of the potting agent 0.2 mm, the depth of the concave portion formed in the ceramic substrate should be 0.35 m or more. It is preferably about 0.45 mm. In this case, the thickness of the ceramic substrate remaining at the bottom of the concave portion is 0.25 to 0.15 mm, and mechanical strength is a concern. However, according to the experiments performed by the present inventors, the mechanical strength is ensured by the thick portion at the peripheral portion, and the package is slightly warped due to the effect of the thin portion of the concave portion. It has been found that the thermal distortion of is reduced. Therefore, it was recognized that the concave portion in the ceramic substrate had a remarkable effect on improving the mounting reliability. Therefore, it is possible to provide a composite package capable of mounting a semiconductor chip with high mounting reliability and high power consumption.

The ceramic substrate is preferably made of one of alumina, aluminum nitride, silicon nitride, mullite, and glass ceramic.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a cross section of a composite package according to an embodiment of the present invention. As shown in FIG. 1, the composite package according to the embodiment of the present invention is a package for a resin-ceramic composite semiconductor element in which a resin substrate 2 and a ceramic substrate 1 are joined, and a semiconductor chip 5 is mounted on the ceramic substrate 1. Recess is formed. The resin substrate 2 has an opening corresponding to the recess.

Specifically, in the resin-ceramic composite package shown in FIG. 1, an aluminum nitride (AIN) substrate 1 having a size of 31 × 31 mm and a thickness of 0.6 mm as a ceramic substrate is used. 1 is provided with a cavity having a depth of 0.4 mm.
The cavity may be opened by laser processing, but a method of processing using a predetermined mold for press processing is easy. A 0.15 mm thick resin substrate 2 having a window (opening) at a portion corresponding to the cavity is bonded thereto, and a 0.4 mm thick semiconductor chip 5 is attached to a 0.05 mm thick conductive adhesive 7.
After mounting using, wire bonding was performed with a bonding wire 6, and further, potting sealing was performed using a potting agent 4. In this case, since the aluminum nitride substrate 1 has a cavity, the protrusion of the potting agent 4 from the surface of the resin substrate 2 is 0.1 m.
m or less. Therefore, the screen printing of the solder paste becomes extremely easy, and thus the joining of the solder balls 3 becomes easy. When the thermal resistance of this package was measured, it was as low as 13.6 ° C./W, and it was possible to cope with the allowable power consumption of about 4 W.

In the structure shown in FIG. 3, the thermal resistance is 20 ° C./W
It can be seen that the structure of the present invention has improved the temperature by 6 ° C./W. Similarly, in the structure of FIG. 3, the allowable power consumption is 2.5 W, so that the improvement of the allowable power consumption of about 1.5 W was obtained.

The depth of the cavity is 0.3 to 0.5.
It may be appropriately selected within the range of mm. The thickness of the ceramic substrate 1 is not limited to 0.6 mm, and may be set to a thickness near 0.6 mm, for example, a value of 0.55 to 1 mm. Also, the thickness of the resin substrate 2 is 0.05 mm to 0.15.
A range of about mm may be used. The depth of these cavities, the thickness of the ceramic substrate, the thickness of the resin substrate, and the like are designed so that the protrusion of the potting agent is 0.2 mm or less, preferably 0.1 mm or less with respect to the predetermined semiconductor chip thickness. do it.

[0020]

As described above, according to the present invention,
It is possible to obtain a composite package for a semiconductor element in which solder ball bonding is easy and the thermal resistance is low.

Further, according to the present invention, a composite package for a semiconductor device having high mounting reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a composite package for a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the structure of a conventional composite package for a semiconductor device.

FIG. 3 is a schematic cross-sectional view showing the structure of a composite package for a semiconductor device studied by the present inventors in the process leading to the present invention.

[Explanation of symbols]

 Reference Signs List 1 ceramic substrate 2 resin substrate 3 solder ball 4 potting agent 5 semiconductor chip 6 bonding wire 7 conductive adhesive

Claims (1)

[Claims] 1. A composite package comprising: a ceramic substrate having a concave portion for mounting a semiconductor element; and a resin substrate having an opening corresponding to the concave portion and bonded to a surface of the ceramic substrate. .