JPS62285432A - Micro formation of electric contact material - Google Patents

Abstract

PURPOSE:To facilitate applying conductive contact material to a group of electrodes on a substrate only by a method wherein surface inactive photopolymer layers are formed on the conductive adhesive surface of a film with conductive adhesive except the parts corresponding to a group of fine terminal electrodes. CONSTITUTION:A sheet with conductive adhesive is composed of a carrier film 1 and heat reactivating conductive adhesive 2 applied to the carrier film 1. The whole surface of the sheet is coated with photoresist 3. Then the resist 3 is exposed and developed by photolithography so as to remove the parts of the resist 3 corresponding to transparent terminal electrodes 5 of a group of electrodes 5 formed on a glass substrate 4. After that, the resist 3 is made to face the substrate 4 on which the electrodes 5 are formed, which is prepared separately, and subjected to thermocompression bonding by hot rolls 6. Then, if the film 1 is removed, the adhesive 2 is transcribed precisely onto the electrodes 5 only. With this constitution, conductive material for electric contact can be applied to terminal electrodes which are formed with extra-fineness and extra high density selectively and precisely.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Field of Application The present invention provides an electrical method for connecting a chip-shaped electronic component, typified by an IC chip, to a group of terminal electrodes on a substrate. The present invention relates to a micro-forming method of electrical readout material in which connecting material is precisely formed only on terminal electrodes on a substrate.

Conventional technology In the past, soldering was often used to connect the 4A terminals of electronic components and the circuit pattern terminals on the board, but in recent years, with the miniaturization of IC flat packages and the increase in the number of connection terminals, soldering has become increasingly popular. , the so-called pitch interval between the contact and VT terminals has become progressively narrower, and it has become increasingly difficult to handle conventional soldering techniques. In addition, recently, in the case of calculators, electronic watches, liquid crystal displays, etc., there has been a movement to try to use the mounting area more efficiently by directly attaching bare IC chips to electrodes on glass substrates, replacing soldering. Effective and fine electrical connection means are highly desired. As a method for electrically connecting a bare IC chip to a transparent electrode on a glass substrate, there are various methods in which the particle size, particle shape, blending amount, etc. are appropriately adjusted, as shown in Japanese Patent Publication No. 51-114439. A conductive adhesive is obtained by uniformly dispersing metal powder in a thermosetting resin, and this is applied to the top surface of the glass electrode.The bumps of the IC chip are aligned with the transparent terminal electrodes, and then pressure bonded. A method has been proposed in which electrical connection is achieved by curing the conductive adhesive to make only the bump portions conductive.

Problems to be Solved by the Invention However, in such a method, the finer the electrodes and the higher the electrode density, the more likely current leakage occurs between adjacent transparent terminal electrodes or between electrodes on a chip. It was something. In order to avoid this current leak, it is possible to selectively print a conductive adhesive only on the transparent terminal electrode group using the conventional screen printing method, but since the IC chip is directly attached, A group of transparent terminal electrodes is formed into a 100 μm opening in the pad shape of an IC chip.
At present, it is considered that it is almost impossible to form with a 200 μm pinch using conventional printing technology.

The present invention has been made in view of the above-mentioned problems, and its purpose is to directly connect the electrode pads of electronic components and the electrode group on the board with high reliability in a fine and dense manner. The object of the present invention is to form a conductive connecting material with high reliability only on electrode groups of electronic components, or electrode pads of electronic components, such as IC chips.

Means for Solving the Problems In order to solve the above problems, the present invention forms a surface-inactive photopolymer layer on the conductive adhesive surface of a conductive adhesive film coated on a carrier film. After that, only the photopolymer corresponding to the fine terminal electrode group of the substrate on which the fine pitch and fine terminal electrodes are formed is removed by photolithography technology, and then the separately prepared fine pitch and fine terminal electrodes are formed. One surface of the substrate containing the fine terminal electrode group is aligned with the surface of the conductive adhesive-attached film on which the photopolymer layer is formed, and bonded by thermocompression.

Thereafter, a film with a conductive adhesive is applied to #I#, and the conductive adhesive is transferred only onto a group of fine terminal electrodes, thereby realizing micro-formation of an electrical connection material.

Function: According to the above-described method of the present invention, a photopolymer layer is formed on the conductive adhesive surface of the conductive adhesive-attached film, the surface of which is inactive except for the portion corresponding to the fine terminal electrode group. , micro-pinch the film with conductive adhesive,
Even if it is thermocompressed to a substrate on which fine terminal electrodes are formed, it will not be transferred to anything other than the fine terminal electrode group, and by using a photopolymer, fine and dense transfer is possible.
Since the transferred conductive adhesives exist independently, connection without current leakage is possible between adjacent electrodes.

EXAMPLE Hereinafter, a method for micro-forming an electrical connection material according to an example of the present invention will be described in detail with reference to the drawings.

1 to 5 are process sectional views showing a first embodiment of the invention, and FIGS. 6 to 11 are process sectional views showing a second embodiment of the invention. Further, FIGS. 12 and 13 show cross-sectional views when an IC chip is mounted on a substrate using the micro-forming method of electrical connection material of the present invention.

In the figure, l is a carrier film, 2 is a heat-reactivated conductive adhesive, 3 is a surface-inactive photoresist, 4 is a glass substrate, 5 is a transparent terminal electrode (ITO electrode), 6 is a hot roll, and 7 is a silicon wafer. , 8 is an electrode pad of an IC chip, and 9 is an IC chip.

In a first embodiment of the present invention, a heat reactivable conductive adhesive 2 is first applied on a carrier film 1 as shown in FIG.
A second layer was applied to the entire surface of the sheet with conductive adhesive formed to a thickness of 30 μm.
The surface is coated with a non-active photoresist 3 as shown in the figure. The photoresist 3 used at this time is surface-inactive, such as silicone resin, and an example thereof is KJR-803O3 (manufactured by Shin-Etsu Silicone Co., Ltd.). However, it is not necessary to limit it to a silicone resin type, and other resin types can be used as long as the photoresist 3 is surface-inactive.

Next, as shown in FIG. 3, by exposing and developing the photoresist 3 using photolithography technology, for example, TTOt with a pitch of 200 μm and a width of 100 μm is formed.
The photoresist 3 corresponding to the ITO electrode 5 of the glass substrate l on which the electrode group is formed is removed. Thereafter, as shown in FIG. 4, a separately prepared glass substrate 1 on which the ITO electrode 5 is formed is placed facing the surface of the photoresist 3 and bonded by thermocompression using a hot roll 6. Thereafter, as shown in FIG. 5, when the carrier film 1 is peeled off, the heat-reactivated conductive adhesive 2 is microtransferred only onto the ITO electrode 5.

In addition, the second embodiment shows a method of micro-transferring a conductive adhesive onto a silicon wafer 7 containing a large number of IC chips instead of a substrate. As shown in FIG. 7, the entire surface of a sheet with a conductive adhesive, in which a heat-reactivated conductive adhesive 2 is formed to a thickness of 20 to 30 μm on a carrier film 1, is coated with a surface inactivation layer as in the first embodiment. Coat with photoresist 3. Next, as shown in FIG. 8, the photoresist 3 is exposed and developed using a photolithography technique, thereby removing the photoresist 3 corresponding to the electrode pad 8 of the IC chip having a diameter of 100 μm. Next, as shown in FIG. 9, a silicon wafer 7 containing a large number of IC chips is
The above-mentioned photoresist 3 is placed facing the photoresist 3 and bonded by thermocompression using a hot roll 6. Thereafter, as shown in FIG. 10, when the carrier film 1 is peeled off, the heat-reactivated conductive adhesive 2 is microtransferred only onto the electrode pads 8 of the IC chip.

Note that when the heat-reactivated conductive adhesive 2 formed on the transparent terminal electrode 5 on the glass substrate 4 obtained in the first example and the electrode pad 8 of the IC chip 9 are faced and thermocompressed, the first 1
The IC chip and the glass substrate can be connected as shown in Figure 2.

In addition, the silicon wafer 7 with the thermally reactivated conductive adhesive 2 on the electrode pad 8 of the IC chip obtained in the second example was cut along the dotted line as shown in FIG. 11 to form individual IC chips 9. It can be connected to a glass substrate as shown in FIG.

Effects of the Invention As explained above, according to the method of micro-forming an electrical connection material of the present invention, a conductive material can be formed on a substrate or on an electrode part of an electronic component, such as an IC chip, by transfer. It is possible to selectively and accurately form conductive materials for electrical connections on ultra-fine and ultra-densely formed terminal electrode groups, which was impossible with printing, and it is possible to form conductive materials for electrical connections with high precision by scratching 1 on the glass substrate of an IC chip. Not only in connection but also in the electrical connection of various electronic components to various substrates, soldering is effective for ultra-fine connections that are difficult to connect, so it has a high practical value.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are process sectional views showing the first embodiment, and FIGS. 6 and 7. 8, 9, 10, and 11 are process cross-sectional views showing the second embodiment, and FIGS. 12 and 13 are IC chips based on the first and second embodiments, respectively. FIG. DESCRIPTION OF SYMBOLS 1... Carrier film, 2... Heat-reactivated conductive adhesive, 3... Surface inactive photoresist, 4... Glass substrate, 5・・・・・・
Transparent terminal electrode (ITOt electrode), 6... Heat roll, 7... Silicon wafer, 8... I
C chip 1! 9...IC chip. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 2 f”l 3.
-&I! D Shizuo + raw rJ7. Figure 3 Figure 5 Figure 6 Figure 10

Claims (1)

[Claims] The process of forming a surface-inactive photopolymer layer on the conductive adhesive surface of the conductive adhesive film coated on the carrier film, and the fine terminal electrode group of the substrate on which the fine pitch and fine terminal electrodes are formed. A step of removing only the photopolymer corresponding to the above using a photolithography technique, and applying the conductive adhesive to one side of the separately prepared substrate on which the fine pitch and fine terminal electrodes are formed, including the fine terminal electrode group. The process includes the steps of thermally pressing the film to the surface on which the photopolymer layer is formed, and peeling off the conductive adhesive-attached film and transferring the conductive adhesive only onto the fine terminal electrode group. Characteristic micro-forming method for electrical connection materials.