Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
2002-06-17
2004-02-17
Whitehead, Jr., Carl (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S713000, C257S783000
Reexamination Certificate
active
06693348
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device in which a contacting point breakage of electrical bonding can be prevented, and to an image scanning unit utilizing the same and an image forming apparatus utilizing the same.
2. Description of the Prior Art
In the prior art technology a wireless bonding is well known, which has advantages in a higher densification of the contact pins and a miniaturization of the semiconductor device by means of connection of a large number of pins which are the contacting point of semiconductor chip onto the contacting points of a substrate when in comparison with the wire bonding in which the bonding pads on the semiconductor chip and the lead on the substrate are connected electrically with the metal fine line.
It is also well known that there is a face down bonding as one of the wireless bonding technology. This face down bonding is a method in that a bump or a beam lead is formed on a bonding pad of the semiconductor chip and the semiconductor chip is directly connected with its chip surface onto a conductor layer of the substrate by putting it with the chip surface down.
As a typical face down bonding method, there is a method called flip chip.
Because there is recently a requirement for miniaturization of semiconductor devices, it has been popular to achieve the semiconductor chip face down bonding with the substrate as a method for further miniaturization of a package of the semiconductor chip and the substrate.
When a semiconductor chip is achieved a face down bonding onto a substrate, it is also well known that a means is employed to prevent a breakage in the circuit, for example, caused by the thermal expansion by means that an adhesive material is used (as a sealing compound) between the semiconductor chip and the substrate in order to prevent an occurrence of a electrical breakage (at contacting point) in a circuit which is caused by a difference in the coefficients of thermal expansion between the semiconductor chip and the substrate.
The thermal expansion generally becomes large in proportion to a difference in temperature and a length of the object. An amount of the expansion is dependent on a coefficient which is different in accordance with the material of object, namely, a coefficient of thermal expansion. Because of the above described reason in an object with longer length such as a line CCD which is used in a copy machine, facsimile, scanner and so on, an amount of the thermal expansion especially along a longer direction becomes extremely large.
Due to this fact even when the adhesive material (sealing compound) is used between the semiconductor chip and the substrate as described above, the electrical contacting point are relatively moved because the difference between the amount of thermal expansion is too large. As a result of this, there was a problem that the contacting point between the semiconductor chip and the substrate was broken.
In the past a semiconductor chip has been well known in that the semiconductor chip and the substrate were covered with a resin which was disclosed in the Japanese Laid Open Patent Hei 05-218230. In this semiconductor chip a semiconductor chip which is mounted with a flip chip structure is covered with a resin, However, there is a problem in the method disclosed in the Japanese Laid Open Patent Hei 06-218230 that the thermal expansion is accelerated because even a back surface of the functional surface of semiconductor chip is also covered with the resin, and thereby a place from which heat generated by high speed driving of the semiconductor chip is radiated, is also covered with resin too, the method can not prevent effectively the breakage of contacting point by the thermal expansion. Especially a significant effect is shown in the semiconductor chip with longer length.
SUMMARY OF THE INVENTION
Because of the above described situation an object of the present invention is to provide a semiconductor chip in which a contacting point breakage of electrical bonding can be prevented, and to provide an image scanning unit utilizing the same and an image forming apparatus utilizing the same.
Another object of the present invention is to provide a semiconductor chip in which a curvature of the semiconductor chip with the optical functional surface by the thermal expansion can be prevented to forbid an occurrence of out of focus, and to provide an image scanning unit utilizing the same and an image forming apparatus utilizing the same.
To achieve the above described objects the present invention provides a semiconductor device including: a semiconductor chip which has a functional surface; a power supplying means which is connected to the functional surface; and a substrate which supports the semiconductor chip and the power supplying means, wherein the semiconductor chip is fixed on the substrate at portion other than a connecting potion between the functional surface and the power supplying means.
A 1st feature of the present invention is a semiconductor device including an assembly in which a semiconductor chip having a functional surface and a power supplying means are electrically connected at the functional surface, characterized by that the assembly is disposed on a substrate with the power supplying means side being the substrate side, and the substrate and the assembly are fixed together at a portion other than the power supplying means portion.
In this structure a pinched portion of the power supplying means is free from the movement of substrate because the substrate and the assembly are fixed through portions other than power supplying means when the substrate and the semiconductor chip make an expansion and contraction in different amount under an influence of heat. Accordingly any stress does not affect on the contacting portion between the power supplying means and the semiconductor chip thereby a breakage of the assembled portion can be prevented.
A 2nd feature of the present invention is a semiconductor device including an assembly in which a semiconductor chip having a functional surface at a front surface and a power supplying means are electrically connected at the functional surface, characterized by that the assembly is disposed on a substrate with the power supplying means side being the substrate side, the power supplying means has a pinched portion between the semiconductor device and the substrate, and the substrate and the semiconductor device are fixed together at a portion other than the pinched portion.
In this structure a pinched portion of the power supplying means is free from the movement of substrate because at least pinched portion of the power supplying means moves integratedly with the semiconductor chip and the pinched portion is not fixed on the substrate when the substrate and the semiconductor chip make an expansion and contraction in different amount under an influence of heat. Accordingly any stress does not affect on the contacting portion between the power supplying means and the semiconductor chip thereby a breakage of the assembled portion can be prevented.
A 3rd feature of the present invention is the semiconductor device according to the 2nd feature and characterized by that an adhesive material which adheres the semiconductor chip and the substrate to fix, is filled at a space between the substrate and the functional surface of the semiconductor chip In this structure in addition to an action by the above described 2nd feature, because the stress caused by the thermal expansion and contraction between the semiconductor chip and the substrate is not concentrated to specific region and the stress is absorbed in entire structure, thereby the local breakage of semiconductor chip and substrate can be prevented.
A 4th feature of the present invention is the semiconductor device according to the above described 2nd feature and characterized by that the adhesive material which adheres the semiconductor chip and the substrate to fix, adheres them with contacting the substrate and a back su
Jr. Carl Whitehead
Smoot Stephen W.
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