JP2650499B2 - Method of forming electrical connection contact and method of mounting electronic component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a chip-shaped electronic component represented by an IC chip to a terminal electrode group on a substrate by forming fine electrical connection contacts only on the terminal electrodes on the substrate. The present invention relates to a method for accurately forming electrical connection contacts and a method for manufacturing a mounting substrate.

[0002]

2. Description of the Related Art Conventionally, soldering has often been used to connect a connection terminal of an electronic component to a circuit pattern terminal on a substrate. The pitch interval has been gradually narrowed, and it has become increasingly difficult to deal with the conventional soldering technique using screen printing of cream solder. In recent years, there has been a movement in calculators, electronic watches, liquid crystal displays, and the like in which a bare IC chip is directly attached to an electrode on a glass substrate to make efficient use of the mounting area. There is a strong need for electrical connection means. As a method of electrically connecting a bare IC chip to the electrodes of the substrate, there is a mounting method called flip chip mounting, which uses a protruding contact (bump) formed on an electrode pad of the IC chip by a plating technique. Is what you do. A known method of forming a protruding contact is to first form a metal plating portion such as chromium (Cr), copper (Cu), or gold (Au) on an electrode pad on an IC substrate, and then use an extra resist and metal deposition. The film is removed to form a protruding contact. Alternatively, plated Au may be used.
It has been proposed to connect the bumps by soldering by a printing method.

[0003]

However, in such a method using the plating technique, the method of forming the protruding contacts and the mounting of the IC chip are considerably complicated, and require many processing steps and advanced etching and plating techniques. Was. Further, in the conventional soldering technique using cream solder by screen printing, the solder supply limit is 0.3 mm pitch, and further fine connection is impossible.

The present invention has been made in view of the above problems, and an object of the present invention is to reliably and directly attach an electrode pad of an electronic component to an electrode group on a substrate with high reliability. Another object of the present invention is to easily and accurately form electrical connection contacts on an electrode group on a substrate or an electronic component, for example, an electrode pad of an IC chip, and to propose a fine connection indispensable for IC chip mounting. .

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for forming an electrical connection contact on a fine terminal electrode of a substrate having a fine pitch and a fine terminal electrode, the method comprising the steps of: Alternatively, a metal ball containing a metal as a main component is pressure-bonded by aligning the fine terminal electrode surface of the substrate with the metal ball in the concave portion, and the metal ball is transferred onto the fine terminal electrode surface to form an electrical connection contact. It is intended to realize the formation.

[0006]

According to the above-mentioned method of the present invention, the projecting contacts can be easily formed on the fine terminal electrodes on the substrate with high reliability and a simple and highly reliable electrical connection contact can be formed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming an electrical connection contact according to an embodiment of the present invention and a mounting board using the same will be described in detail with reference to the drawings.

FIGS. 1 (a) to 1 (c) are process sectional views showing a first embodiment of a method for forming an electrical connection contact according to the present invention. FIGS. 2A and 2B are cross-sectional views showing a mounting process for mounting an IC chip on a substrate using the method for forming an electrical connection contact of the present invention.

In FIG. 1, 1 is a supporting substrate having a concave portion, 2 is a metal ball mainly composed of a low melting point alloy or metal, 3 is a heating head, 4 is an IC chip, 5 is an electrode pad of the IC chip, 6 is a bump (protruding contact), FIG.
In (b), 7 is an Au thick film electrode, 8 is a ceramic substrate, and 9 is a heating head.

In the first embodiment of the present invention, first, FIG.
As shown in (a), a metal ball 2 mainly composed of a low melting point alloy or a metal is filled in a concave portion provided on the surface of a support substrate 1. The supporting substrate 1 is a glass substrate etched in a hydrofluoric acid aqueous solution and provided with a concave portion having a depth of 100 μm □ and a depth of 50 μm. The metal ball 2 mainly composed of a low melting point alloy or metal has a particle size of 50 to 70 μm. A eutectic solder ball consisting of: Next, as shown in FIG. 1 (b), the supporting substrate 1 is heated to 230 ° C. by using a heating head 3 to melt the filled metal balls 2, and as shown in FIG. Fig. 1
As shown in (c), the metal ball 2 made of a low melting point alloy or metal is transferred only on the electrode pad 6, and the electrical connection contact 6 is formed at a time. Also, as shown in FIGS. 2 (a) and 2 (b), the electrical connection contact 6 made of a low melting point alloy or metal 2 and the ceramic substrate 8 on the electrode pad 5 of the IC chip 4 obtained in the first embodiment. After the Au thick-film electrode 7 is opposed to and pressure-bonded, the protruding contact 6 is re-melted and fixed by the heating head 9.
Connection with u-thick film electrode is possible.

Next, a second embodiment of the present invention will be described. FIG.
(A) to (e) are process sectional views showing a second embodiment of the present invention. Numeral 10 denotes a two-step protruding contact, which is shown in FIG.
(A) to (c) show a process in which the molten low melting point alloy or metal ball 2 in the concave portion provided in the support base 1 is transferred onto the two-step protruding contact. This two-stage projecting contact 10
Has a loop-shaped two-step protruding structure in which the capillary is drawn in a loop-like locus using a wire bonding apparatus. FIG.
(D) to (e) are cross-sectional views of a mounting process using the electrical connection contact of the present invention using the two-step protruding contact obtained in FIGS. 3 (a) to 3 (c).

In the above embodiment, an example is shown in which the IC chip 4 on which the electrical connection contacts are formed is mounted on the ceramic substrate 8, but the substrate on which the IC chip is mounted is not limited to the ceramic substrate. Needless to say, for example, a glass epoxy substrate, a glass substrate, a flexible printed substrate, or the like may be used. The metal ball 2 mainly composed of a low melting point alloy or metal has a diameter of 5
A eutectic solder ball composed of particles having a particle size of 0 to 70 μm was used, but the material was an alloy mainly composed of lead (Pb), tin (Sn), and indium (In) or a simple substance thereof, or Au.
A low melting point alloy or metal such as -Sn20% or Au-Sn90% may be used. When the metal ball is formed by heating the ball, the diameter of the metal ball is larger than the depth of the concave portion provided on the surface of the supporting base material. Any metal ball adjusted to be large may be used. Furthermore, when the electrode pad on the IC chip and the metal ball formed by melting are pressed and pressed against each other, the application of ultrasonic vibration or scrub (small sliding) ensures the connection between the IC chip and the metal ball. .

Although glass is used as the supporting substrate having the concave portions, other materials may be used. For example, a stainless steel plate may be etched and a surface thereof may be coated with a ceramic coat such as TiC. . Further, the atmosphere for forming the metal ball or for mounting the IC chip on the substrate by re-melting the protruding contacts may be not only in the air but also a nitrogen atmosphere, a reducing atmosphere using hydrogen, or the like. In this embodiment, the flux is not applied, but the application of the flux at a necessary stage of the process is not limited at all.

[0014]

As described above, according to the method for forming the electrical connection contact of the present invention, the electrical connection contact is selectively and accurately formed from the low melting point alloy or metal on the electrode pad portion of the IC chip. Can be easily formed at once by transferring metal balls, which is effective not only for the connection of the IC chip to the electrodes on the ceramic substrate, but also for the ultra-fine connection that is difficult in the past for the electrical connection to various substrates. Very practical value because it demonstrates. In addition, the substrate connected and mounted using the electrical connection contact of the present invention can effectively and minimize the area of the mounting substrate without any leads around the IC chip.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a mounting process according to the first embodiment of the present invention.

FIG. 3 is a process sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support base material 2 Metal ball which has a low melting point alloy or metal as a main component 3 Heating head 4 IC chip 5 IC chip electrode pad 6 Bump (protruding contact) 7 Au thick film electrode 8 Ceramic substrate 9 Heating head 10 Two-step projection Projecting contact

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-30140 (JP, A) JP-A-62-2435 (JP, A) JP-A-64-5039 (JP, A) JP-A-2-50 312240 (JP, A) JP-A-59-148352 (JP, A) Masatoshi Takemoto 1 High-reliability micro-soldering technology. twenty one

Claims (2)

(57) [Claims] 1. An electrical connection contact on a terminal electrode of an electronic component
A method of forming a filling in a recess provided a metallic ball on the support substrate surface, two-stage protruding protrusion contacts
Is formed on a terminal electrode group of the electronic component,
Electrical connection contacts forming method, wherein a two-stage protruding projecting contact point and pressed to fit the metal ball is composed of the step of transferring the metal ball on the protruding contact. 2. A metal ball is provided on a surface of a supporting substrate.
The process of filling recesses with two-stage projecting contacts
Are formed on the terminal electrode group of
The contact point is pressed against the metal ball and the metal
Transferring the metal balls onto the protruding contacts;
Consists of a process of melting and connecting to the electrodes on the circuit board
An electronic component mounting method characterized by being performed.