JPS61174643A - Method of connection for wiring substrate - Google Patents

Abstract

PURPOSE:To extremely lessen the conductive resistance of a wiring substrate and to enable to perform a highly reliable connection of the wiring substrate with a semiconductor integrated circuit chip by a method wherein a bonding agent layer obtainable by dispersing low-melting point metal particles in an insulative bonding agent is provided between the conductive patterns and the conductive materials to corespond to the conductive patterns, both of the conductive patterns and the conductive materials are pressed and heated and are electrically connected, and after that, both of the conductive patterns and the conductive materials are cooled to the prescribed temperature in a state being pressed. CONSTITUTION:A release sheet is peeled off from a coupling sheet and a bonding agent layer 5 using the release sheet as its supporting material is placed on parts of the surfaces of conductive leads 4, 4... on a substrate, where the conductive leads 4, 4... should be at least connected with the bonding pads 2, 2... of a semiconductor integrated circuit chip 1, in such a way as to be continuously placed on the parts as one layer. Then, the integrated circuit chip 1 is placed on the bonding agent layer 5 in such a way that the bonding pads 2, 2... are superposed on the parts, where the bonding pads 2, 2... should be mutually connected with the conductive leads 4, 4... to correspond to the bonding pads 2, 2..., through the bonding agent layer 5, and both of the bonding pads 2, 2... and the conductive leads 4, 4... are heated and pressed. Accordingly, solder metal particles 7 are fused and crushed and both of the bonding pads 2, 2... and the conductive leads 4, 4... are soldered and are electrically connected. After that, both of the bonding pads and the conductive leads are cooled in a state that the pressing to both thereof is continued intact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wiring board connection method suitable for use, for example, in connecting a semiconductor integrated circuit chip to a wiring board such as a film carrier tape.

[Conventional technology]

In general, a semiconductor integrated circuit chip (1) is relatively small, for example, a square with 51 sides as shown in FIG. ing. Conventionally, bonding pads (2), which are electrodes of such a semiconductor integrated circuit chip (1), and, for example, external leads (4) of a film carrier tape have been connected by a wire ending method. This wiring method uses Au wire or aA wire.
This is a method of connecting the mounting I# of the semiconductor integrated circuit chip (1) with the external leads using extremely thin wires such as I wires, but this mounting requires skill and is not easy to work with. prone to hindrance (
There were drawbacks such as poor yield.

Therefore, the applicant of the present application previously proposed a connection method using an adhesive in which low-melting point metal particles are dispersed in an insulating adhesive, as shown in Japanese Patent Application No. 58-250786.

To explain the case where this semiconductor integrated circuit chip (1) is placed on a film carrier tape, this film carrier tape is adhered to a flexible substrate (3) made of polyimide as shown in FIGS. 1 and 5. thickness 18
A Cu foil with a thickness of μm is selectively etched and notarized to form a plurality of binding pads (2), (21...K) on a semiconductor integrated circuit chip (1), which are electrically connected in correspondence with each other. Conductive lead (41, (41...
... was formed.

To connect and fix this semiconductor integrated circuit chip (1) on the film carrier tape, an adhesive layer (5
) Prepare a connecting sheet coated with

The adhesive layer (5) of this connection sheet used a paint in which solder metal particles (7) were dispersed in a hot melt type insulating adhesive (6). The insulating adhesive (6) had the following composition.

10 parts by volume of low melting point solder metal particles (7) were dispersed in 100 parts by volume of the solid content of the insulating adhesive K having this composition. These metal particles are added to the Pb-8n alloy with sb and Bi.
The average particle size was 20μ with the melting point of 140C.
The solder metal particles of the book were used. Insulating adhesive (
6) An adhesive paint in which K low melting point solder metal particles (7) were dispersed was applied onto a release sheet using a coater so that the thickness after drying was 20 μm to obtain a connection sheet. The release sheet of the connection sheet thus obtained is peeled off and connected to at least the I/IF leads (2) of the semiconductor integrated circuit chip (1) on each conductive lead (4) on the substrate (3). Place the adhesive layer (5) over the desired area, and place the integrated circuit chip (K) on top of this as shown in Figure 2.
1) are placed on the conductive leads (4) corresponding to the conductive leads (2) so that the parts to be connected to each other overlap via the adhesive layer (5), and both are bonded at 170°C.
Pressure bonding was carried out under C for 15 seconds at 50 ky/chip. In this way, since the adhesive in the adhesive layer (5) becomes fluid when heated, pressure is applied, especially since the adhesive in the adhesive layer (5) substantially protrudes from the mutually facing surfaces of the substrate (3) and the integrated circuit chip (1). Much of the insulating adhesive (6) interposed between the conductive lead (4) on which the wire is hung and the corresponding indexing 74 (2) is pushed out to the side, and these conductive leads (4) The solder metal particles (7) are heated and pressurized between the sharpening/nding pad (2) and the third
As shown in the figure, it is melted and crushed, and the conductive lead (4) and the connecting wire (2) are soldered to electrically connect them.

In this case, by heating and pressurizing, the insulating adhesive (6) in a highly fluid state is extruded outward from between the conductive lead (4) and the danding/IP lead (2),
The two are well fused together by the solder metal, and the insulating adhesive (6) pushed out of the connection area wraps the conductive metal particles (7) well, and this adhesion is maintained between the adjacent connection areas. Due to the presence of a large amount of the agent (6), the substrate (3) and the semiconductor integrated circuit chip (1) are firmly fixed to each other.

[Problem that the invention seeks to solve]

However, the conduction resistance between the gendering/mother wire (2) and the corresponding conductive lead (4) varied widely, with an average of 100 or more. The present inventor has conducted various studies on this and found that this conduction resistance is relatively large when the pressure is stopped while heating to 170C, for example, when the Aj sputtering surface is 14° (2). It was found that this is because the so-called "1 wetting" of the solder metal particles (7) to the solder metal particles (7) was not very good, and as the solder metal particles (7) were cooled thereafter, the contact area of the solder metal particles (to the A1 side of the force) became smaller.

In view of this point, the present invention is designed to reduce the conductive resistance value between the semiconductor integrated circuit chip (11) and the conductive leads (4) of a film carrier tape, for example, to improve reliability. The purpose is to enable high-quality connections.

[Means for solving problems]

The method of connecting the wiring board of the present invention is as shown in FIG. 4),
(41...K) has a plurality of electrically connected conductors (2), (21...!...),
These conductive/# turns (4), (4)... and the corresponding conductors (21, (21...) are superimposed and an insulating adhesive (6) is applied between them. An adhesive layer (5) in which low-melting point metal particles (7) are dispersed is placed on the surface of the adhesive layer (5), and the conductive/4' turns (4), (4) are heated under pressure.
...and the corresponding conductor (2), (2) song...
* and are electrically connected by melting the metal particles (7), and are then cooled down to a predetermined temperature while maintaining this pressurized state.

[Effect]

According to the present invention, the conductive patterns (41, (41...
An adhesive layer (5) in which low melting point metal particles (7) are dispersed in an insulating adhesive (6) is arranged between the song and the corresponding conductor (21, (2+...), The conductive no-turns (41) are melted by applying pressure and heating between these metal particles (7).
, (41. (7) and conductive/mother turn (4), (41/curve/and conductor (2+
, (21...) are the same as when the metal particles (7) are melted, and the conductive turns (4), (4)... and the conductors (2+, ( 2)...
The conductive resistance between the cable and the cable is extremely small, for example, less than 1Ω, allowing a highly reliable connection.

〔Example〕

An embodiment of the wiring board connection method of the present invention will be described below with reference to the drawings.

In this example, as shown in FIGS. 1 and 5, there are a plurality of ending nodes (2), (2
) is the conductive lead (4) of the film carrier tape.

(4)...K connection is performed as described below. As mentioned above, this film carrier tape is made by selectively etching a 18 μm thick Cu foil adhered to a flexible substrate (3) made of monoimide to form a semiconductor integrated circuit chip (1). A plurality of conductive leads (4) , (4
)...is what the song was formed from.

To connect and fix this semiconductor integrated circuit chip (1) on the film carrier tape, an adhesive layer (5
) Prepare a connecting sheet coated with The adhesive layer (5) of this connection sheet is made of a hot-melt type insulating adhesive (6) with solder metal particles (7) dispersed in the same manner as described above.

Peel off the release sheet of this connection sheet to remove the conductive leads (4), (4)... Place the adhesive layer (5) over the parts to be connected to (2), (2)..., and place the second adhesive layer on top of this.
As shown in the figure, an integrated circuit chip (1) is connected to each other on a corresponding conductive lead (41, (4)... The parts to be bonded are placed on top of each other with the adhesive layer (5) interposed between them, and both are heated and pressed for 15 seconds using 17or:, 5oky/chip.In this case, the insulating adhesive in the adhesive layer (5) is heated. The conductive leads (41) exhibit fluidity and are therefore subject to pressure, especially since they substantially protrude from the mutually facing surfaces of the substrate (3) and the integrated circuit chip (1).
, (4)... and the corresponding landing pad (2), (21...), much of the insulating adhesive (6) is pushed out to the side. These conductive leads (4).

(4)...... and Gending's arm (21, (
As shown in FIG. 3, the solder metal particles (]) are melted and crushed between the conductive leads (4) by heating and pressurizing them between the conductive leads (4).

(4)...and? landing pad (2),
(2) . . . are soldered to electrically connect them.

In this example, after that, while the pressure of 50 kf/f between the two is continued, the pressure is increased to 60 kf/f, for example.
Cool until it reaches 11.

Landing pad (2), (2)
... Curved conductive lead (41, (41...) The conduction resistance at the connection part with the bend was less than 1Ω, and the insulation resistance between adjacent connection parts was 109Ω or more.

In this way, the conduction resistance at the connection part is made sufficiently small,
The reason why the insulation resistance between the connecting parts can be made sufficiently high is that the insulating adhesive (6), which has been made highly fluid by heating and pressurizing, has a conductivity of +7 w (41, (41・
·····and? Ending/Marriage (2), (21
The insulating adhesive (6) is extruded outward from between the two, and the two are well fused together by the solder metal, and the insulating adhesive (6) extruded out of the connection is bonded to the conductive metal particles (7).
), and if there is a large amount of this insulating adhesive (6) between adjacent connection parts, the substrate (3)
) and the semiconductor integrated circuit chip (1) are firmly fixed.

In this case, in this example, the conductive leads (41, (41・
...... and Danding Pad (21, (2)
After the solder metal particles (7) have successfully fused the .
Solder metal particles (7) and conductive leads (4), (41
...and Gonding/Datsud (2).

(2)... The contact area with this conductive lead (
41, (41...... and danding pad (21
, (2) . . . can be made extremely small, and all of the connecting portions can be, for example, 1Ω or less, and a highly reliable connection can be achieved.

In addition, the heating temperature during the above-mentioned bonding, in other words.

The melting point of the metal particles is 50C to 350C1, preferably 800C
~260C. The heating temperature, that is, the melting point of the metal particles, is selected to be 50C or higher, preferably 80C or higher, because the integrated circuit device is mounted in, for example, an electronic device, that is, in use, and is lower than 50C, preferably lower than 80C. At an ambient temperature of In order to avoid this, selecting a temperature of 350C or less, preferably 260C or less makes it difficult to select a substrate material that can withstand heat treatment exceeding this temperature, and the heating means and work become complicated, which is an industrial disadvantage. It depends on what is happening.

Further, in the above example, the temperature was cooled to 60C, but this temperature was below the melting point of the low melting point metal particles (7), and the insulating adhesive (60C) was cooled to 60C.
) loses its fluidity, which is actually a predetermined temperature of 80C or less, up to room temperature.

In addition, the metal particles have a particle diameter of 70 mm, which corresponds to the distance between the conductive leads (4) and the connecting nodes (2), that is, the distance between adjacent conductive leads (4), and the distance between adjacent conductive leads (4). It is desirable that the distance between the indentation and armpit (2) be selected to be less than or equal to the distance between the two.
It has been confirmed that accidents such as short circuits between adjacent connections due to metal particles can be reliably avoided.

Furthermore, the mixing ratio of the adhesive and metal particles in the adhesive layer that is pre-formed into a sheet or that is pre-coated on the substrate to be interposed between the conductive leads and the corresponding bonding pads is determined by the adhesive layer. (Solid content) 0.5 to 50 parts by volume of metal particles is selected for 100 parts by volume. If this is less than 0.5, low resistance connection may be insufficient.
According to K, if the amount exceeds 50 parts by volume, the insulation between the metal particles other than the connection portion may become incomplete or the mechanical adhesion strength may become insufficient.

In addition, the insulating adhesive used for this purpose is an adhesive that has at least m-flow properties under the pressure and heating conditions during bonding described above, such as a rubber-based adhesive or an ethylene-vinyl acetate-based adhesive. A hot-melt type adhesive or a thermosetting adhesive based on a thermosetting resin that undergoes thermal crosslinking can be used.

Further, in the above-mentioned example, a plurality of conductive leads and corresponding conductive leads to be connected are layered by interposing an adhesive layer formed in advance into a sheet, or
By applying an adhesive layer on the conductive leads or pasting them together, and applying heat and pressure to the conductive leads through the adhesive layer, a large amount of insulation can be created between the conductive leads and the bonding pad that overlap each other. The adhesive is expelled to other parts by its fluidity, and the metal particles provide good conductivity - bonding/welding between the leads and the four terminals, and the insulating adhesive pushed out of the connection part becomes conductive. The presence of a large amount of this adhesive between adjacent joints allows for a strong mechanical fixation, but this phenomenon is not effective. k, which makes the conduction resistance 0.1Ω or less and the insulation resistance 107Ω or more, preferably 109Ω, is M@F@I (melt flow index) during heat bonding of the insulating adhesive, and is 0.001. The above is preferably o, oos or more. This M@F・■ is ASTM, D1238 A
law or JIS.

This is a book that shows the number of grams of resin that flows out of an oriice (hole) in 10 minutes when a load of 2160 f is applied at a predetermined compression temperature using a device specified by Method A of K7210. Further, the thickness of the insulating adhesive layer is 10 to 300% of the space volume generated between each connection part, preferably 30 to 2%.
00%, and its thickness is preferably 5 to 200 μm.

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, the conductive pattern (41, (4)...
... and the corresponding conductor (21, (21...
Insulating adhesive (6) k Low melting point metal particles (7)
are dispersed, a nine adhesive layer (5) is arranged, and the metal particles (7) are melted by applying pressure and heating between the two equal parts, thereby making the conductive particles (4), (4)... conductive. Body (2),
(2) ...... and then cooled to a predetermined temperature in this pressurized state, so that the low melting point metal particles (7) and the conductive I4 turns (4), ( 4)
...and conductor (2).

(2)...What contact area is this metal particle (7)
This conductive mother turn (41,
(4)... and conductor (2+, (2+...
... The conductive resistance between the two is extremely small, for example, 1Ω or less, which has the advantage of allowing highly reliable connections.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are diagrams for explaining an embodiment of the wiring board connection method of the present invention, FIG. 4 is a bottom view showing an example of a semiconductor integrated circuit chip, and FIG. FIG. 3 is an enlarged plan view of main parts of the wiring board. (1) is a semiconductor integrated circuit chip, (2) is a metal bonding motherboard, (3) is a substrate, (4) is a conductive lead, (5)
) is an adhesive layer, (6) is an insulating adhesive, and (7) is a solder metal particle. Figure 4 Figure 5

Claims (1)

[Claims] It has a substrate on which a plurality of conductive patterns are arranged, and a plurality of conductors that are electrically connected in correspondence with the plurality of conductive patterns, and the conductive patterns and the corresponding conductors are overlapped. An adhesive layer having low melting point metal particles dispersed in an insulating adhesive is placed between the two, and the conductive pattern and the corresponding conductor are heated under pressure.
A method for connecting wiring boards, comprising electrically connecting by melting the metal particles, and then cooling to a predetermined temperature while maintaining the pressurized state.