Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Bump leads
Reexamination Certificate
2000-07-07
2002-06-11
Lam, Cathy (Department: 1775)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Bump leads
C257S735000, C257S778000, C257S780000, C257S784000
Reexamination Certificate
active
06404052
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to multi-layer substrates, and particularly to multi-layer substrates suitable for mounting of semiconductor devices such as integrated circuits.
2. Related Art
In the related art, multi-layer substrates having high degree of freedom with respect to wiring are used as a substrate for mounting semiconductor devices such as integrated circuits. Reference numeral
106
in
FIG. 9A
is a multi-layer substrate, and is made up of a plurality of laminated single layer substrates
101
.
Each single layer substrate
101
comprises a base film
122
formed of a polyimide film, a wiring film
115
disposed on the base film
122
, and an adhesive film
121
arranged on the wiring film
115
and the base film
122
. Conductive bumps
116
are formed on the wiring film
115
, and the tips of the bumps
116
project from the top of the adhesive film
121
. The base film
122
is subjected to patterning a specified locations of a rear surface of the wiring film
115
are partially exposed.
When a plurality of the single layer substrates
101
are laminated on top of one another, bumps
116
of one single layer substrate
101
confront the rear surface of the wiring film
115
of a single layer substrate
101
laminated on top of it, tips of the bumps
116
are brought into contact with the rear surface of the wiring film
115
, and they are then stuck together using the adhesive film
121
, a multi-layer substrate
106
having a desired number of films is obtained.
The surface of this multi-layer substrate
106
is covered by a protective film
120
, and bumps represented by reference numeral
116
a
project from the surface of the protective film
120
.
Reference numeral
133
represents a semiconductor device, and has a plurality of circuits formed insides. This circuit is connected to bonding pads
134
formed on the semiconductor device
133
. The bonding pads
134
confront the surface of the multi-layer substrate
106
, the bonding pads
134
are made to contact the bumps
116
a
, as shown in
FIG. 9B
, thermo-compression bonding is carried out to melt a soldered film of the surface of the bumps
116
a
, and the circuits inside the semiconductor device
133
are connected to the wiring films
115
inside the multi-layer substrate
106
via the bonding pads
134
and the bumps
116
a
. When a semiconductor device
133
in chip form is mounted on a multi-layer substrate
106
described above, there is no need to package the semiconductor device
133
, contributing significantly to miniaturization of an electronic device.
However, if the semiconductor device
133
is mounted on the multi-layer substrate
106
of the related art described above, the overall thickness of the multi-layer substrate
106
is disadvantageously increased by the thickness of the semiconductor device
133
.
Also, with the multi-layer substrate
106
of the related art, since it is necessary to protect the semiconductor device
133
, when the semiconductor device
133
is covered with resin
135
, as shown in
FIG. 9C
, the overall thickness is further increased by the thickness of the resin
135
.
In recent years, in the field of portable telephones and lap top and palm top personal computers, there has been a demand for further miniaturization and thinning of appliances, which has lead to the demand for multi-layer substrates to be thin even when semiconductor devices are mounted on them.
SUMMARY OF THE INVENTION
The present invention has been conceived in view of the above described problems in the related art, and the object of the present invention is to provide a multi-layer substrate that does not suffer increased thickness, even when semiconductors are mounted.
In order to solve the above described problems, a multi-layer substrate of the present invention comprises a plurality of at least first single layer substrates.
A first single layer substrate used in the present invention has a first resin film, a first wiring film arranged on the first resin film, and through holes passing through from a front surface to a rear surface.
In the present invention, at least two of the first single-layer substrates are electrically connected together, and the through holes are arranged so as to be aligned, forming a housing section.
Generally, the surface area of a semiconductor chip is 1 mm
2
or more, which means that it is necessary for the surface area of each of the through holes to also be at least 1 mm
2
, and the surface area of opening of the housing section formed by laminating the through holes also becomes at least 1 mm
2
. The depth of the housing section is determined by the number of first single layer substrates laminated on top of one another.
Also, the first single layer substrate of the present invention has first bumps connected to the first wiring film and first connection holes formed on the first resin film, the first wiring film being located on the bottom surface of the first connection holes.
In another aspect of the present invention, of two adjacent first single layer substrates, first bumps of one first single layer substrate are connected to positions of the first wiring film at bottoms of the first connecting holes of the other first single layer substrate.
Accordingly, the multi-layer substrate of the present invention has desired first wiring films within laminated first single layer substrates electrically connected.
In another aspect of the multi-layer substrate of the present invention, a first adhesive film arranged on the first wiring film and exhibiting adhesiveness upon application of heat is provided on the first single layer substrates, and tips of the first bumps project from the surface of the first adhesive surface.
In this case, a plurality of the first single layer substrates are placed in adhered while heating, and the first single layer substrates are stuck together by the resultant adhesive force of the first adhesive layer.
In yet another aspect of the multi-layer substrate of the present invention also has a second single layer substrate.
In a still further aspect, the second single layer substrate comprises a second resin film, and a second wiring film arranged on the second resin film, with no through holes at least at positions where the housing section is formed.
This second single layer substrate is further laminated on the laminated first single layer substrates, and the second single layer substrate is located on the bottom surface of the housing section.
Further, another aspect of the multi-layer substrate of the present invention has the second wiring film of the second single layer substrate electrically connected to at least part of the first wiring film of the first single layer substrate adjacent to the second single layer substrate.
Also, the second single layer substrate of the multi-layer substrate of the present invention has second bumps connected to the second wiring film, the second bumps being connected to the first wiring film located in bottom sections of the first connection holes of the first single layer substrate adjacent to the second single layer substrate.
Also, the second single layer substrate of the multi-layer substrate of the present invention has second connection holes, arranged on the second resin film, the second wiring film being located on a bottom surface of the second connection holes, and first bumps of the first single layer substrate adjacent to the second single layer substrate are connected to positions of the second wiring film at the bottoms of the second connection holes.
A still further aspect of the second single layer substrate of the multi-layer substrate of the present invention has a second adhesive layer, arranged on the second wiring film, exhibiting adhesiveness upon application of heat, and tips of the second bumps project from a surface of the second adhesive film, the second single layer substrate laminated to the first single layer substrate by adhesive force of the second adhesive layer.
The multi-layer substrate of the present
Kurita Hideyuki
Nakamura Masayuki
Lam Cathy
Oliff & Berridg,e PLC
Sony Chemicals Corp.
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