JPH01303745A - Package for solid-state image sensing element - Google Patents

Abstract

PURPOSE:To improve the heat dissipation effect of a package and to make it possible to inhibit the temperature rise of a sensor chip by a method wherein a solid-state image sensing element is provided with a thermal conductor having a thermal conductivity superior to that of a parent material constituting the package. CONSTITUTION:A thermal conductor 4 of a thermal conductivity better than that of a package parent material 1 is buried in the lower part of a sensor chip 3 which is large in a calorilic value. One end of the conductor 4 is brought into contact to the rear of the chip 3, the other end is led out outside of a package and the end is provided with such a heat dissipation mechanism as a heat sink to improve a heat dissipation efficiency. That is, a path, which is constituted of the conductor 4, is low to a thermal resistance and can diffuse heat rapidly to the exterior. Thereby, heat, which is conducted to the sensor chip, is reduced and the temperature of the chip can be held lowly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a solid-state image sensor package, and more particularly, to a solid-state image sensor package that can suppress a rise in temperature of a sensor chip.

[Conventional technology]

Solid-state imaging devices, which have many features such as small size, light weight, low power consumption, and high reliability, have been rapidly developing in recent years with the development of process technology. In particular, solid-state imaging devices using charge-coupled devices (hereinafter referred to as COD) are rapidly increasing the number of pixels in order to improve resolution. Therefore, the number of horizontal COD transfer stages increases, and the electrode capacitance increases more than ever. Moreover, the horizontal drive frequency for driving this becomes high.

In driving a horizontal COD, the power consumption is, for example, rC
As described in "Fundamentals of CD" by Tetsuo Tsukamoto; published by Ohmsha, when the electrode capacitance C1 is the drive voltage V and the drive frequency is J, it is given by the following equation.

Power consumption P = f - C - V2 ... (1) High-quality television camera driven by two-phase, two-channel CCD1
When configured with an image element, it is expected that the driving conditions will be f = 37.1 MHz, capacitance per equivalent C = 250 PF, and V = 7 V, and the power consumption for horizontal drive is approximately 4 per equivalent.
50mW, reaching as much as 900mW in two-phase.

[Problem to be solved by the invention]

This power is consumed by the wiring resistance of the horizontal COD electrode,
This generates heat and causes the temperature of the sensor chip to rise. C.C.
In the D image sensor, a rise in temperature brings about an increase in thermal noise and dark current, which causes deterioration in image quality. However, no measures have been taken to suppress the temperature rise in the conventional image sensor packages.

FIG. 2 is a sectional view of a conventional package. This package includes a base material 1 made of ceramic and metal terminals (hereinafter referred to as pins) 2 that transmit drive signals and the like for an image sensor. The sensor chip 3 is directly attached to the package base material 1 made of ceramic, and the generated heat is transmitted from the horizontal CCD to the sensor chip to the package and is radiated. Therefore, the chip temperature becomes higher than the package temperature. This heat dissipation route is not necessarily a good heat dissipation route in terms of the temperature rise of the sensor chip. When a CCD image sensor, which is actually in practical use, was mounted on a camera board and operated, the sensor chip became hotter than the package.6 COD devices for high-quality television cameras, which have a higher drive frequency, reach even higher temperatures. It is considered to be.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image sensor package that can enhance the heat dissipation effect and suppress a rise in temperature of a sensor chip.

[Means to solve the problem]

In order to achieve the above object, the present invention embeds a material (hereinafter referred to as a thermal conductor) with better thermal conductivity than the package base material under the horizontal COD, which generates a large amount of heat, or under the sensor chip. One end of this thermal conductor is brought into contact with the back surface of the sensor chip, and the other end is drawn out to the outside of the package. Installing a heat sink or other heat dissipation mechanism at this end increases heat dissipation efficiency.

[Effect]

The path formed by the thermal conductor has low thermal resistance and can quickly diffuse heat to the outside.

That is, the heat generated by the horizontal COD is quickly conducted to a heat sink outside the chip, and is radiated by this heat sink. Therefore, the heat conducted to the sensor chip is reduced and the chip temperature can be kept low. This makes it possible to suppress the generation of dark current and thermal noise.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure is a diagram showing a cross section of a package of an image sensor according to the present invention. This package is composed of a base material 1 made of ceramic, metallic pins 2 for inputting and outputting drive signals, etc., and a thermal conductor 4 made of metal or the like whose thermal conductivity is superior to that of the ceramic base material. Note that 5 is a bonding wire that connects the pins of the package and the sensor chip, and 12 is a bonding pad.

In this package, since the optical image is incident from the top surface, the surface of the thermal conductor is exposed below the surface to which the sensor chip 3 is attached, and is brought into contact with the sensor chip 3. The thermal conductor 4 has a structure that penetrates the package body and transmits heat to the outside of the package from the back surface.

FIG. 3 is a diagram showing the position of the horizontal CCD 8° output amplifier 7 in the solid-state image sensor. The ccDma element is the light receiving part 6
．． Horizontal CCD8. The output amplifier 7 is arranged as shown in FIG. As described above, in the CCD sensor, the horizontal CCD section 8 generates a large amount of heat. In addition to this, there is also a lot of heat generated in the output amplifier section 7 through which a large amount of current flows. FIG. 4 is a top view of the package shown in FIG. 1, and is a diagram showing the positional relationship between the sensor chip 3 and the package. The hatched portion is the position where the thermal conductor 4 is embedded. That is, the thermal conductor 4 connects the horizontal CCD 8 . It is placed below the output amplifier 7. With the above configuration, horizontal CCD
8, and the output amplifier section 7 -> thermal conductor 4 -> outside of the package, and heat is radiated through a portion with low thermal resistance. As a result, from the horizontal CCD 8 to the sensor chip 3 (especially the light receiving section 6),
), and the temperature rise of the sensor chip 3 can be suppressed.

FIG. 5 is an embodiment showing a modification of FIG. 1. The difference from the embodiment shown in FIG. 1 lies in the size and position of the heat conductor forming the heat radiation path. In FIG. 1, the thermal conductor is provided only under the horizontal CCD and the output amplifier, but in the embodiment shown in FIG. 5, the thermal conductor is provided over the entire lower part of the sensor chip.

FIG. 6 is a view of the package shown in FIG. 5 viewed from the back side, and as shown, a thermal conductor is provided so as to cover the entire lower part of the sensor chip. With the above structure, horizontal COD,
A path can be configured to radiate not only the heat generated by the output amplifier but also the heat generated by the light receiving section to the outside. Also horizontal CCD
This has the effect of quickly dissipating the heat generated by the output amplifier that has been conducted through the chip.

FIG. 7, like FIG. 5, is a diagram showing a modification of the embodiment of FIG. 1. The difference between the embodiments of FIG. 7 and FIG. 5 is that the thermal conductor is larger. From the standpoint of heat dissipation, it would be better if the entire package was made entirely of metal with good thermal conductivity.

The solid-state image sensor has 20 pin terminals for inputting and outputting signals.
Where are the books? These must be supported by insulators. Furthermore, the bonding pad 12 used for connecting the package and the sensor chip 3 must also be constructed on an insulator. Therefore, as shown in FIG. 7, most of the package is made of metal with good thermal conductivity, and only the parts that support the pins and the parts where the bonding pads are provided are made of insulating material.

FIG. 8 shows a view of the package shown in FIG. 7 from the back side.

The entire package is made of metal, with only the pin support portion made of insulator. In this way, the heat dissipation effect can be further enhanced. It can be easily inferred from the above explanation that if an insulating material has a thermal conductivity comparable to that of metal, the entire package may be made of that material.

FIG. 9 shows an embodiment in which a heat sink 9 is attached to the thermal conductor 4. The heat conducted by the thermal conductor 4 is radiated by the heat sink 9. Thereby, the heat transferred to the outside by the thermal conductor 4 can be effectively radiated.

It is even better if forced air cooling is applied to increase the heat dissipation effect.

Also, instead of the heat sink 9, an electric cooling device such as a Peltier device may be used.

It's no good.

FIG. 10 shows an embodiment in which a Peltier element is provided.

When a current is passed through a Peltier element, one side becomes colder and the other side becomes hotter. As shown in the figure, the low-temperature side surface of the Peltier element 13 is brought into contact with the thermal conductor 4, and the thermal conductor 4 absorbs the heat of the sensor chip 3 that has become black and radiates the heat to the outside.

Note that although the optical image passes through the package of the solid-state image sensor, there is a protective glass that protects the sensor from moisture, dust, and the like. Although the description of this protective glass is omitted in the above description, it is sufficient to attach the protective glass 10 to the package as shown in the cross-sectional view of FIG. 11.

The gist of the present invention is to provide a heat dissipation path made of a material with excellent thermal conductivity below the sensor chip. The thermal conductivity of currently used alumina ceramic packaging materials is 0.04 to 0.1 (cal-cffi/, cJ-
see・℃), but for example, in metals, silver: 1.0.
Copper: 0.94, Gold: 0.74. Tungsten: 0.39
(cal-aIl/d-9ec·°C). Therefore, it is easy to understand that the metals with excellent thermal conductivity shown above can be used as the thermal conductor.

Among them, copper is superior in terms of thermal conductivity, cost, and workability. However, the thermal conductor is not necessarily a metal, but may be any material as long as it has a thermal conductivity comparable to that of the above-mentioned metals or a thermal conductivity superior to ceramics. Also, its shape does not matter. For example, although the path becomes longer, it is also possible to radiate heat to the board by bringing the thermochloride into contact with the screws used to attach the package to the board. Furthermore, a heat conductor may be brought into contact with the casing of the camera to radiate heat to the casing.

Further, according to the present invention, it is not necessary to use a material with excellent thermal conductivity for the package base material 1, and it is possible to use a material with excellent thermal conductivity only in the portion that generates a large amount of heat.

For example, even if an inexpensive resin with poor thermal conductivity is used for the package base material, a heat dissipation path is ensured by the thermal conductor. Therefore, there is also the effect of reducing the cost of the package.

〔Effect of the invention〕

As described above, according to the present invention, the heat generated by the sensor chip can be efficiently extracted to the outside of the package by being transmitted through the thermal ocean body → the heat sink and the low thermal resistance portion.

This heat can be forcibly radiated using a heat sink or electronic cooling device. As a result, the temperature rise of the sensor chip can be suppressed, and a signal from the solid-state image sensor with less thermal noise and dark current can be obtained. Furthermore, an inexpensive material such as resin can be used for the package base material, which has an excellent effect of lowering the package cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a solid-state image sensor package according to the present invention, FIG. 2 is a sectional view of a conventional image sensor package, FIG. 3 is a diagram showing the horizontal COD and the position of an output amplifier in a sensor chip, and FIG. The figure shows the positional relationship between the sensor chip and the package, FIGS. 5 and 7 are other examples of packages for solid-state image sensors, and FIG. 6 is a view of the package shown in FIG. 5 from the back side. Figure 8 is a view of the package in Figure 7 seen from the back, Figure 9 is an example in which a heat sink is attached to the package in Figure 1, Figure 10 is an example in which a Peltier element is attached to the package, and Figure 11 is an example in which a Peltier element is attached to the package. FIG. 3 is a diagram showing a cross section of the package. 1... Package made of ceramic, 2... Sensor chip, 3... Terminal (bottle), 4... Heat conductor, 5
... bonding wire, 6... light receiving section, 7...
Output amplifier section, 8...Horizontal COD (H-CCD)
, 9... Heat sink, 10... Protective glass, 12
...Pounding pad, 13...Peltier element. Chapter l, v, 2, extortion, 3, V, 4, 2 and 0, 5, ro, 7, 3rd country, 3, the deceased, 1, 5, 7,

Claims (1)

[Scope of Claims] 1. A package for a solid-state image sensor, comprising an insulating material that supports at least a signal input/output terminal, and a thermal conductor having higher thermal conductivity than the insulating material. A distinctive solid-state image sensor package. 2. The solid-state imaging device package according to claim 1, wherein the thermal conductor is provided below the solid-state imaging device. 3. A solid-state imaging device package, wherein the thermal conductor is in thermal contact with the solid-state imaging device. 4. The package for a solid-state imaging device according to claim 3, wherein the position where the thermal conductor comes into contact is a high-temperature part of the solid-state imaging device. 5. A solid-state imaging device package comprising at least a light receiving section, a horizontal charge transfer path, and an output amplifier, the lower part of the horizontal charge transfer path and output amplifier having better thermal conductivity than the base material forming the package. A package for a solid-state image sensor characterized by being provided with a thermal conductor.