JPH0448690A - Connection of wiring glass substrate with circuit substrate - Google Patents

Abstract

PURPOSE:To reduce the processes for a wiring glass substrate to the minimum and to conduct electric connection securely by a method wherein the wiring glass substrate is cut along dicing lines and the wiring pattern surface of a circuit substrate which corresponds to longitudinal sections or the side faces of bumps mounted on the wiring glass substrate for circuit substrate connection is brought into contact with the longitudinal sections or the side faces of the bumps to be connected to the wiring glass substrate electrically. CONSTITUTION:Thin-film wirings 2, solder bumps 4 for mounting a solid-state image sensing device 3 and solder bumps are formed on a glass substrate 1. After that, the glass substrate 1 is cut along dicing lines 1a to obtain a wiring glass substrate 6. Then, the solid-state image sensing device 3 is mounted on the wiring glass substrate 6 through the bumps 4. Nextly, a copper foil is stuck on the surface of a polyimide resin film 8 and is photo-etched to form wirings 9 and connection terminals of the wirings 9 are solder-plated. The thus fabricated flexible circuit substrate 7 and the wiring glass substrate 6 are connected electrically and united into one body by bringing the connection terminals of the flexible circuit substrate 7 into contact with the bumps for connecting the circuit substrate and melting the solders on both sides together.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method of connecting a wiring glass substrate and a circuit board, and particularly relates to a method of connecting a wiring glass substrate on which a solid-state image sensor is mounted to a circuit board. Regarding the connection method suitable for

(Prior Art) As electronic devices are desired to be smaller and have higher performance, it is necessary to mount more electronic components in devices with smaller external dimensions. Therefore, the space that can be used to mount circuit elements such as electronic components is often limited in volume and shape.

For example, when using an electronic endoscope, it is necessary to minimize the discomfort felt by the patient, to be able to take as many images as necessary, and even to provide treatment methods for the patient. Therefore, there is a need for mounting means that can reduce the diameter of the image pickup tube as much as possible, arrange the necessary component parts, and then arrange the electrical circuit components in the remaining space.

Considering the tip of an electronic endoscope to be approximately cylindrical,
The natural configuration is to have an optical means such as a lens at its tip, and to arrange a solid-state image sensor behind it so that its imaging surface faces in the axial direction. In addition, the wiring for driving this solid-state image sensor and transmitting image information must be pulled out toward the base of the electronic endoscope. When arranged like this, it corresponds to the back side of the element.

For example, Japanese Patent Application No. 82-3186 discloses a structure for reducing the diameter of the cylindrical tip in such an arrangement.
No. 85 (Japanese Unexamined Patent Publication No. 1-161795) discloses a thick board with electronic components mounted on the front or back surface, and a flexible wiring board for connecting the electronic components to the outside. A circuit board has been proposed in which a flexible wiring board is electrically connected to a side surface of the board that is not parallel to the electronic component mounting surface. In order to realize this structure, electrical wiring must be formed between the electronic component mounting surface of the thick board and the side surface to which the flexible board is electrically connected.

As a method of forming such wiring, for example, Japanese Patent Application No. 1983
-288118 (Japanese Unexamined Patent Publication No. 1-129488), a thick conductor film is formed on the side surface of an insulating substrate, and then a thin film wiring pattern is formed on the surface to be connected to the end surface of the conductor film on the side surface. A means of forming the

If this means is applied to the above-mentioned structure, the structure will be such that the insulating substrate is a glass substrate, the solid-state image sensor is connected to a thin film wiring pattern, and the flexible wiring board is connected to a thick film conductor film. It is possible.

(Problems to be Solved by the Invention) The above means can achieve a relatively reliable connection in a relatively simple process compared to other conventionally known means. In view of the fact that the formation of wiring patterns must be performed sequentially, and that there is always a risk of wire breakage occurring at the edge portions of the glass substrate, a more improved process is desired.

In view of this point, the present invention provides a wiring glass substrate and a circuit board that minimize processing on the wiring glass substrate and ensure electrical connection between the circuit board connected to the side surface and the wiring on the glass substrate surface. This provides a method for connecting with

[Structure of the Invention] (Means for Solving the Problems) A method for connecting a wiring glass substrate and a circuit board according to the present invention includes providing bumps in advance on the wiring glass substrate, and connecting the wiring glass substrate at a position vertically traversing the bump or adjacent to the bump. The main idea is to cut the wiring glass substrate at a certain position and to integrate the vertical section of the bump or the side surface of the bump adjacent to the cut surface of the wiring glass substrate with the wiring pattern of the circuit board.

That is, the method for connecting a wiring glass substrate and a circuit board according to the present invention includes the following embodiments.

(a) A method of connecting a wiring glass substrate on which a solid-state image sensor is mounted as a semiconductor device and a circuit board.

(b) A method for connecting a wiring glass substrate and a circuit board, characterized in that the circuit board connection bumps are also used as electrode connection bumps of a semiconductor device.

(C) Wiring characterized by fusing and connecting the longitudinal section of the circuit board connection bump or the side surface of the circuit board connection bump and the wiring pattern of the circuit board by heat of at least the surface of the circuit board wiring pattern. How to connect glass substrate and circuit board.

(d) Wiring characterized by forming a planar wiring corresponding to the wiring pattern of the circuit board over the longitudinal section of the circuit board connection bump or the side surface of the circuit board connection bump and the cut surface of the wiring glass substrate. How to connect glass substrate and circuit board.

(Function) The bumps provided on the glass substrate are used for electrical connection between the wiring provided on the surface of the wiring glass substrate and the circuit board connected to the side surface of the wiring glass substrate. to ensure that In other words, by cutting the glass substrate at a position that traverses the bump or a position adjacent to the bump, the vertical section of the bump or the side surface of the bump adjacent to the cut surface of the wiring glass substrate can be cut.
It becomes substantially flush with the cut surface of the glass.

Thus, the bumps provided on the wiring glass substrate, which also serve to connect the wiring formed on the surface of the wiring glass substrate or the wiring glass substrate and the electrodes of the semiconductor device, are arranged almost perpendicularly to the cut surface of the wiring glass substrate. It easily contacts the wiring pattern of the circuit board to be integrated, and a reliable or highly reliable electrical connection is achieved and maintained. In particular, the cross section of the bump exposed on the cut surface of the wiring glass substrate or the cross section of the wiring in the vicinity is connected (contacted) to the wiring surface of the circuit board.
Larger area creates better and more reliable electrical connections.

(Example) An example of a method for connecting a glass substrate and a circuit board according to the present invention will be described below with reference to FIGS. 1(a) to (c).

FIGS. 1A to 1E are cross-sectional views schematically showing a method of connecting a wiring glass substrate and a circuit board in a mounting or assembling process of a solid-state image sensor for an electronic endoscope.

First, a glass substrate 1 made of optical glass is prepared, and before dicing the glass substrate 1, a required thin film wiring 2 is formed on a predetermined surface of the glass substrate 1, and a solid-state image sensor 3 is mounted using an electrolytic plating method. solder bumps 4 are provided. Further, in the electrolytic plating step, a solder bump 5 connected to at least one end of the thin film wiring 2 was provided at a position straddling the dicing line 1a of the glass substrate 1 (FIG. 1(a)). These solder bumps 5 are used to connect wiring patterns on a circuit board in a process described later.

After forming the thin film wiring 2, solder bumps 4 and solder bumps 5 for mounting the solid-state image sensor 3, etc., the glass substrate 1 is cut with a diamond blade dicing saw along the dicing line la, and the solid-state image sensor 3 is mounted. A wiring glass substrate 6 was obtained.

In other words, the wiring glass substrate 6 for mounting the solid-state image sensor 3 is exposed such that the vertical cross section of the solder bump 5 is flush with the cut surface 6a along the dicing line 1a of the glass substrate 1.
I got it.

The thus obtained wiring glass substrate 6 for mounting the solid-state image sensor 3
In contrast, the required solid-state image sensor 3 is face-down CO
It was mounted and mounted using the G technology via the element mounting bumps 4 (FIG. 1(b)).

On the other hand, a flexible circuit board 7 made of polyimide resin as a base material was prepared as a circuit board. That is, a flexible wiring board 7 was prepared by photoetching a copper foil laminated to 8 sides of a polyimide resin film to form wiring 9, and soldering the connection terminal portions.

Next, the flexible circuit board 7 and the side surface of the wiring glass substrate 6 on which the solid-state image sensor 3 is mounted are connected so that the connection terminals of the flexible circuit board 7 and the circuit board connection bumps 5 of the wiring glass board 6 are aligned with each other. After the side substrate 7 is brought into contact (face-to-face) and fixed with a jig, the side substrate 7 is
．． By melting the solder between the connection terminal 6 and the circuit board connection bump 5, electrical connection was established and the side board 6 was integrated (FIG. 1(C)).

In the above embodiment, the connection terminal surface of the flexible circuit board 7 and only the vertical section of the circuit board connection bump 5 of the wiring glass substrate 6 are brought into contact (contact), and the connection terminal of the side board 7.6 is connected to the circuit. Electrical connection was made by melting the solder of the board connection bumps 5, but it may also be done in the following manner. That is, as shown in perspective in FIG. 2, a resin-based silver paste, for example, is screen printed on the side surface (cut surface) 6a of the wiring glass substrate 6, and a conductor layer 10 connected to the circuit board connection bumps 5 is formed. If this is done, electrical connection with the circuit board 7 can be easily established using, for example, an anisotropically conductive adhesive sheet. Of course, the formation of the conductor layer IO is not limited to the resin-based silver paste, and may be formed by a metal vapor deposition method.

Further, the position of the circuit board connection bumps 5 formed on the surface of the glass substrate 1 is set near the dicing line 1a of the glass substrate 1, and when the glass substrate 1 is cut, as shown in cross section in FIG. The side surface of the substrate connection bump 5 may be flush with the cut surface 6a of the glass substrate 1.

Furthermore, in the above, the solder bumps 4 for mounting the solid-state image sensor 3 and the bumps for connecting the circuit board 5 were separately provided on the surface of the glass substrate 1, but as shown in cross section in FIG. Dicing line 1a of the glass substrate 1
It may be set at or near the position.

The connection method according to the present invention is not limited to the above-mentioned examples, and can be widely applied to, for example, mounting and assembling semiconductor devices such as memory elements and logic elements. Also,
In addition to using solder bumps for the connection, face-down COG method using bumps of other metals such as gold may be used, and face-up connection such as wire bonding is also possible.

Further, the connection to the circuit board may be made of metal other than solder, and an adhesive sheet or adhesive may be used to enhance the strength of the connection portion.

Furthermore, the circuit board does not need to be flexible as in the example above, and it is of course possible to mount and mount the semiconductor device on the wiring glass substrate after electrically connecting the wiring glass substrate and the circuit board. good.

[Effects of the Invention] According to the present invention, it is possible to easily connect a wiring glass substrate for mounting a semiconductor device or a wiring on a wiring glass substrate to a circuit board whose surface is in contact with the side surface of the wiring glass substrate in a substantially perpendicular direction. It can be done. Moreover, the electrical connection between the wiring glass substrate side and the circuit board side maintains high reliability. Therefore, electronic devices such as electronic endoscopes can be mounted with high density.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (c) schematically show the mounting process of a solid-state image sensor for an electronic endoscope, which is an embodiment of the method for connecting a wiring glass substrate and a circuit board according to the present invention. FIG. 2 is a perspective view showing another configuration example of a wiring glass substrate used in the method of connecting a wiring glass substrate and a circuit board according to the present invention, and FIGS. 3 and 4 are cross-sectional views according to the present invention. FIG. 7 is a cross-sectional view showing still another example of the structure of the wiring glass substrate used in the method for connecting the wiring glass substrate and the circuit board. 1... Glass substrate 1a... Dicing line 2... Thin film wiring 3... Solid-state image sensor (semiconductor device) 4...
・Solder bump 5 for mounting solid-state image sensor...Solder bump 6...Wiring glass substrate 6a...Cut surface (side surface) of wiring glass substrate 7.
...Circuit board 8...Polyimide resin film 9...
Wiring 1.0...Conductor layer 4 raw purchase available (Available for mounting 0 Applicant: Toshiba Corporation

Claims (1)

[Claims] In a method for connecting a circuit board and a wiring glass substrate on which a semiconductor device is mounted or to be mounted, a circuit board is connected to a circuit board on or adjacent to a dicing line. A process of cutting a wiring glass substrate provided with board connection bumps along a dicing line, and applying a corresponding wiring pattern surface of the circuit board to the longitudinal section or side surface of the circuit board connection bumps on the cut wiring glass board. 1. A method for connecting a wiring glass substrate and a circuit board, comprising a step of bringing them into contact with each other and electrically connecting them.