Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For high frequency device
Reexamination Certificate
1999-03-03
2001-03-20
Williams, Alexander O. (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For high frequency device
C257S099000, C257S434000, C257S435000, C257S079000, C257S680000, C257S668000, C257S725000, C257S724000, C257S704000, C257S710000, C257S773000, C438S119000, C438S613000
Reexamination Certificate
active
06204556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a structure for and method of mounting an image taking element such as a CCD on a substrate.
2. Description of the Related Art
There have been in wide use image taking elements such as a CCD. Generally such an image taking element is provided with a plurality of pins for electrical connection on one side thereof and is mounted on a substrate provided with a plurality of pads for electrical connection with the pins on the element. Further there has been known a structure in which the pads are provided on the image taking element and the pins are provided on the substrate.
Recently there has been provided a back-exposure type image taking element which is provided with a sensor portion on one side thereof and with a light receiving face on the side opposite to said one side as disclosed, for instance, in Japanese Unexamined Patent Publication Nos. 6(1994)-318688 and 6(1994)-318689.
The back-exposure type image taking element is advantageous over the normal image taking elements, which have a light receiving face on the side on which the sensor portion is provided, in that they are higher in sensitivity and have sufficient sensitivity even for ultraviolet rays.
However since it is necessary that the distance between the light receiving face and the sensor portion is very small in order to obtain a sufficient sensitivity, the back-exposure type image taking element is very small in its overall thickness. Therefore the back-exposure type image taking element is apt to be damaged by external force when mounting the element on a substrate and mounting yield is very low.
Though methods of mounting such a back-exposure type image taking element are disclosed in Japanese Unexamined Patent Publication Nos. 6(1994)-318688 and 6(1994)-318689, these methods cannot substantially increase the mounting yield.
SUMMARY OF THE INVENTION
In view of the foregoing observations and description, the primary object of the present invention is to provide a structure and method which can mount at a high yield on a substrate an image taking element such as a back-exposure type image taking element which is not apt to be damaged.
In accordance with an aspect of the present invention, there is provided a structure for mounting an image taking element, which has on its one side one of a pin group and a pad group which are to be brought into electrical contact with each other, on a substrate which is provided with the other of the pin group and the pad group, wherein the improvement comprises that
said one side of the image taking element is bonded to the substrate with each pin of the pin group opposed to one of the pads of the pad group by way of an anisotropic conductive adhesive layer which exhibits electrical conductivity only in a direction substantially perpendicular to said one side of the image taking element.
The anisotropic conductive adhesive layer may be suitably formed by use of thermosetting anisotropic conductive adhesive film exhibiting electrical conductivity only in the direction of thickness.
In accordance with another aspect of the present invention, there is provided a method of mounting an image taking element, which has on its one side one of a pin group and a pad group which are to be brought into electrical contact with each other, on a substrate which is provided with the other of the pin group and the pad group, wherein the improvement comprises the steps of
positioning the image taking element and the substrate so that each pin of the pin group is opposed to one of the pads of the pad group,
providing thermosetting anisotropic conductive adhesive film exhibiting electrical conductivity only in the direction of thickness between said one side of the image taking element and the substrate, and
subsequently heating the thermosetting anisotropic conductive adhesive film to thermoset the same, thereby bonding said one side of the image taking element to the substrate.
It is possible to form a back-exposure type image taking element by polishing the side of the image taking element opposite to said one side thereof after the image taking element is bonded to the substrate and forming the side into a light receiving face.
In accordance with the present invention, since the image taking element is bonded to the substrate by way of a conductive adhesive layer, the image taking element is not subjected to a large external force during mounting on the substrate, whereby even the aforesaid back-exposure type image taking elements can be mounted at a high yield without damage due to external force.
Further since an anisotropic conductive adhesive layer which exhibits electrical conductivity only in a direction substantially perpendicular to said one side of the image taking element is employed as the conductive adhesive layer, only the pin and the pad which are opposed to each other are electrically connected by way of the adhesive layer and the pins and the pads which are not opposed cannot be electrically connected.
Further since the pins and the pads opposed to each other are electrically connected by way of the adhesive layer, the image taking element can be mounted on the substrate at relatively low cost as compared with when special bumps or the like are formed for electrical connection of the pins and pads.
Further when a back-exposure type image taking element is formed by polishing the side of the image taking element opposite to said one side thereof after the image taking element is bonded to the substrate and forming the side into a light receiving face, the polishing operation is facilitated since the image taking element has been fixed to the substrate, whereby manufacturing yield of the image taking element is increased.
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patent: 6-318688 (1994-11-01), None
patent: 6-318689 (1994-11-01), None
Fuji Photo Film Co. , Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Williams Alexander O.
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