JPH04263434A - Formation of electric connection contact and manufacture of mounting board - Google Patents

Abstract

PURPOSE:To enable the title electric connection contacts to be formed easily and collectively by a method wherein the recessions provided on the surface of a supporting base material are filled up with the metallic balls mainly comprising a low melting point alloy or a metal and then the fine terminal electrode surface of a board is oppositely pressure-fixed on the metallic balls 2 which are to be transferred to the electrode surface. CONSTITUTION:The recessions provided on the surface of a supporting base material 1 are filled up with metallic balls 2 mainly comprising a low melting point alloy or a metal. Next, the supporting base material 1 is heated at about 230 deg.C using a heating head 3 to melt down the metallic balls 2. Finally, when the electrode pads 5 of an IC chip 4 are oppositely pressure-fixed on the metallic balls 2, the metallic balls 2 can be transferred only to the electrode pads 5 so as to collectively form the title electric connection contacts 6.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention aims to connect a chip-shaped electronic component such as an IC chip to a group of terminal electrodes on a board by forming minute electrical connection contacts only on the terminal electrodes on the board. The present invention relates to a method for accurately forming electrical connection contacts and a method for manufacturing a mounting board.

0002

[Prior Art] In the past, solder was often used to connect the connection terminals of electronic components and the circuit pattern terminals on the board, but in recent years, with the miniaturization of IC flat packages, etc. As pitch spacing has become increasingly narrower, it has become increasingly difficult to cope with conventional cream solder screen printing soldering techniques. Also,
Recently, there has been a movement toward efficient use of mounting area by directly attaching bare IC chips to electrodes on glass substrates for calculators, electronic watches, and liquid crystal displays. A means of connection is highly desired. There is a mounting method called flip-chip mounting that electrically connects a bare IC chip to the electrodes of the board, and this uses protruding contacts (bumps) formed on the electrode pads of the IC chip using plating technology. It is something to do. A known method for forming protruding contacts is to first deposit chromium (Cr), copper (Cu), and gold (Au) on electrode pads on an IC substrate.
), etc., and then remove excess resist and metal deposited film to form protruding contacts. Furthermore, as another method, it has been proposed to connect plated Au bumps via solder using a printing method.

0003

[Problems to be Solved by the Invention] However, in such a method using plating technology, the method of forming the protruding contacts and the mounting of the IC chip are quite complicated, requiring a large number of processing steps and advanced etching and plating technology. Ta. Further, in the conventional soldering technology using screen printing of cream solder, the solder supply limit is 0.3 mm pitch, and even finer connections are impossible.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a method for directly and reliably bonding electrode pads of electronic components and electrode groups on a substrate finely and densely. , to easily and accurately form electrical connection contacts on electrode groups on a substrate or on electrode pads of electronic components, such as IC chips, and to propose micro-connections that are essential for IC chip mounting. .

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention uses a low melting point alloy in forming electrical connection contacts on fine terminal electrodes of a substrate on which fine pitch and fine terminal electrodes are formed. Alternatively, a metal ball containing metal as a main component is crimped so that the fine terminal electrode surface of the substrate is aligned with the metal ball in the recess, and the metal ball is transferred onto the fine terminal electrode surface to form an electrical connection contact. It is an attempt to realize the formation.

[0006]

[Function] According to the above-described method of the present invention, protruding contacts can be easily and reliably formed all at once on fine terminal electrodes on a substrate, and simple and highly reliable electrical connection contacts can be formed.

[0007]

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 below with reference to the drawings.

FIGS. 1(a) to 1(c) are process cross-sectional views showing a first embodiment of the method for forming electrical connection contacts of the present invention. Moreover, FIGS. 2(a) and 2(b) show cross-sectional views of a mounting process in which an IC chip is mounted on a substrate using the method for forming electrical connection contacts of the present invention.

In FIG. 1, 1 is a supporting base material having a concave portion, 2 is a metal ball whose main component is 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. 2(a) (
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.
), metal balls 2 whose main component is a low melting point alloy or metal are filled into the recesses provided on the surface of the support base material 1. The supporting base material 1 is a glass substrate etched in a hydrofluoric acid aqueous solution to provide a recess of 100 μm □ 50 μm deep, and the metal balls 2 whose main component is a low melting point alloy or metal are particles of 50 to 70 μm. A eutectic solder ball consisting of Next, as shown in FIG. 1(b), the supporting base material 1 is heated to 230° C. using the heating head 3, the filled metal balls 2 are melted, and the electrode pads 5 are connected to the metal balls as shown in the figure. 1 (c) when crimped against 2
), the metal balls 2 made of a low melting point alloy or metal are transferred only onto the electrode pads 6, and the electrical connection contacts 6 are formed at once. Further, as shown in FIGS. 2(a) and 2(b), electrical connection contacts 6 made of a low melting point alloy or metal 2 are placed on the electrode pads 5 of the IC chip 4 obtained in the first example, and After the Au thick film electrodes 7 are pressed against each other and the protruding contacts 6 are remelted and fixed by the heating head 9, the IC chip and the Au thick film electrodes on the ceramic substrate can be connected.

Next, a second embodiment of the present invention will be described. Figure 3 (
(a) to (e) are process cross-sectional views showing a second embodiment of the present invention. 10 is a two-stage protruding contact, as shown in Fig. 3(a).
) to (c) show the steps of transferring the molten low-melting point alloy or metal ball 2 in the recess provided in the support base material 1 onto the two-stage protruding contact. This two-stage protruding contact 10 was formed into a loop-shaped two-stage protruding structure by drawing a loop-like locus on the capillary using a wire bonding device. Figure 3(d)
3(e) are cross-sectional views of the mounting process using the electrical connection contact of the present invention using the two-stage protruding contact obtained in FIGS. 3(a) to 3(c).

[0012] In the above embodiment, an example was shown in which the IC chip 4 on which electrical connection contacts were formed was mounted on the ceramic substrate 8, but the substrate on which the IC chip is mounted is not limited to a ceramic substrate. Needless to say, for example, a glass epoxy substrate, a glass substrate, a flexible printed circuit board, etc. may be used. The metal ball 2 whose main component is a low melting point alloy or metal has a diameter of 5.
We used eutectic solder balls consisting of particles of 0 to 70 μm, but the material was alloys mainly consisting of lead (Pb), tin (Sn), and indium (In), or their single substances, or Au.
- It may be a low melting point alloy or metal such as 20% Sn or 90% Au-Sn, and when the ball is heated to form a metal ball, the diameter of the metal ball is larger than the depth of the recess provided on the surface of the support base material. Any metal ball that is adjusted to be large may be used. Furthermore, when the electrode pads on the IC chip and the metal ball formed by melting are pressed against each other, applying ultrasonic vibration or scrubbing (micro-sliding) will ensure the connection between the IC chip and the metal ball. .

Further, although glass is used as the support base material having the recessed portions, other materials may be used. For example, it is also possible to use a stainless steel plate etched and coated with a ceramic coating such as TiC on the surface. . Further, the atmosphere when forming the metal balls or when mounting the IC chip on the substrate by remelting the protruding contacts is not limited to air, but may also be a nitrogen atmosphere, a reducing atmosphere using hydrogen, or the like. Furthermore, although flux application is not performed in this embodiment, there is no limitation in any way to applying flux at a necessary stage of the process.

[0014]

As explained above, according to the method for forming electrical connection contacts of the present invention, electrical connection contacts can be formed selectively and precisely from low melting point alloys or metals on the electrode pads of IC chips. It can be easily formed all at once by transferring metal balls, and it is effective not only for connecting IC chips to electrodes on ceramic substrates, but also for electrical connections to various substrates, which are conventionally difficult to make ultra-fine connections. It has extremely high practical value. Moreover, the board mounted using the electrical connection contact of the present invention has no leads around the IC chip, and the mounting board area can be effectively and minimized.

[Brief explanation of the drawing]

[Fig. 1] Process cross-sectional diagram showing a first embodiment of the present invention.

[Figure 2
】Cross-sectional view of the mounting process showing the first embodiment of the present invention

[Figure 3]
Process cross-sectional diagram showing the second embodiment of the present invention

[Explanation of symbols]

1 Support base material 2 Metal ball mainly composed of a low melting point alloy or metal 3 Heating head 4 IC chip 5 Electrode pad of IC chip 6 Bump (protruding contact) 7 Au thick film electrode 8 Ceramic substrate 9 Heating head 10 Two-stage protrusion shaped protruding contact

Claims (7)

[Claims] 1. A step of filling a recess provided on the surface of a supporting base material with a metal ball whose main component is a low melting point alloy or metal, and crimping the fine terminal electrode surface of the substrate to the metal ball in the recess. A method for forming an electrical connection contact, comprising the step of transferring the metal ball onto the surface of the fine terminal electrode. 2. While heating at least one of a substrate having a group of fine terminal electrodes and a support base material, the surface of the fine terminal electrodes on the substrate is pressed against the metal balls filled in the recesses, thereby forming the metal balls. 2. The method of forming an electrical connection contact according to claim 1, further comprising a step of transferring only onto said fine terminal electrode. 3. At least one of ultrasonic vibration and scrubbing (micro-sliding) is applied while the fine terminal electrode surface on the substrate is pressed against the metal ball filled in the recess. A method for forming an electrical connection contact according to claim 1. 4. The method is characterized in that the metal ball is adjusted such that the diameter of the metal ball whose main component is a low melting point alloy or metal is larger than the depth of the recess provided on the surface of the support base material. The method of forming an electrical connection contact according to claim 1. 5. Filling the recesses provided on the surface of the supporting base material with metal balls whose main component is a low-melting point alloy or metal; A method for forming an electrical connection contact, comprising the step of transferring the metal ball onto the protruding contact on the fine terminal electrode group by pressing the metal ball in accordance with the metal ball. 6. A step of filling a recess provided on the surface of a supporting base material with a metal ball whose main component is a low melting point alloy or metal, and crimping the fine terminal electrode surface of the substrate to the metal ball in the recess. and transferring the metal ball onto the fine terminal electrode surface, and remelting the protruding electrode formed on the fine terminal electrode surface and connecting it to an electrode group on another substrate. A method for manufacturing a mounting board characterized by: 7. Filling the recesses provided on the surface of the supporting base material with metal balls whose main component is a low melting point alloy or metal, the protruding contact surface of the substrate on which the protruding contacts are formed on the micro terminal electrode group. Transferring the metal ball onto the fine terminal electrode surface by crimping the metal ball in the recess, remelting the protruding electrode formed on the fine terminal electrode surface and transferring the metal ball onto another substrate. A method for manufacturing a mounting board, comprising a step of connecting to an electrode group.