Active solid-state devices (e.g. – transistors – solid-state diode – Encapsulated – With specified filler material
Reexamination Certificate
1998-11-25
2001-05-08
Lam, Cathy (Department: 1775)
Active solid-state devices (e.g., transistors, solid-state diode
Encapsulated
With specified filler material
C257S098000, C257S435000, C257S789000, C174S254000
Reexamination Certificate
active
06229223
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flexible printed board and, more particularly, to a flexible printed board on which a semiconductor element is flip-chip-bonded.
2. Description of the Related Art
In a conventional compact device such as a camera, a flexible printed board is frequently employed to arrange various electric circuits in a compact housing. A technical means for bonding an element such as an IC by a so-called flip chip bonding method is also known.
This flip chip bonding method is a bonding method for arranging an element such as an IC on a printed board upside down. According to this method, an external electrode on the IC is subjected to a bump (projection) process to directly connect the external electrode to the pattern of the board or to connect the external electrode to the pattern through conductive particles. As a concrete example of the flip chip bonding method, a bonding method is disclosed in Japanese Examined Patent Publication No. 62-6652, Japanese Unexamined Patent Publication No. 7-211423, and the like.
A general flexible printed board is formed such that a copper foil is interposed between sheets each having a thickness of several tens &mgr;m. Since the sheet consists of an almost transparent material such as polyimide or polyester, the flexible printed board is considerably inferior to a hard printed board in light-shielding property.
When a semiconductor element such as an IC is bonded on a flexible printed board being inferior in light-shielding property by the flip-chip bonding method, the following drawbacks occur. More specifically, when such a flexible printed board is applied to a product such as a camera which is used under outside strong light or a product used to guide object light to the inside of the product, sunlight, illumination light, or leakage light from a built-in electronic flash, a date LED, or the like is incident on the surface of the semiconductor element such as an IC because the flexible printed board itself is inferior in light-shielding property as described above. As a result, in the semiconductor element, a change in performance or an erroneous operation is disadvantageously caused by a photo-electric effect.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a flexible printed board, although a semiconductor element is flip-chip-bonded on the flexible printed board, which can shield the semiconductor element surface from external light.
It is a second object of the present invention to provide a flexible printed board, although a semiconductor element is flip-chip-bonded on the flexible printed board, which can easily prevent a change in performance, an erroneous operation, or the like caused by the photo-electric effect of an element on a semiconductor.
In short, the present invention relates to a flexible printed board on which a semiconductor element is flip-chip-bonded, and is characterized in that an element formation surface of the semiconductor element is shielded from light by a light-shielding member.
These as well as other objects and advantages of the present invention will become further apparent from the following detailed explanation.
REFERENCES:
patent: 5087964 (1992-02-01), Hatta
patent: 5233130 (1993-08-01), nishino
patent: 5317195 (1994-05-01), Ishikawa et al.
patent: 5394014 (1995-02-01), Ishikawa et al.
patent: 5748448 (1998-05-01), Hokari
patent: 5990565 (1999-11-01), Chang
patent: 6028773 (2000-02-01), Hundt
patent: 60-180132 (1985-09-01), None
patent: 7-211423 (1995-08-01), None
Lam Cathy
Olympus Optical Co,. Ltd.
Volpe and Koenig P.C.
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