JPS62101042A - Loading structure to substrate of ic chip - Google Patents

Abstract

PURPOSE:To improve the workability of a loading process to a substrate of an IC chip by interposing anisotropic conductive adhesives between the IC chip and the substrate and bonding both the IC chip and the substrate. CONSTITUTION:A conductor pattern L on a circuit substrate B is covered with an insulating coverlet K. The coverlet K is removed only in a section connected to an IC in the conductor pattern. An IC pattern on an IC chip is covered with a passivation 10 (an insulating film) with the exception of a pad F section for connection. An insulating coat 20 is applied onto the circumferential side surface of the IC chip. The peripheral section of a resin as a mother material for an anisotropic conductive adhesive sheet C is protruded by pressing, thus realizing the sealing effect of the periphery of the IC.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a connection and termination method when an IC chip is mounted on a circuit board.

B. Conventional technology Conventionally, when attaching an IC chip to a substrate, the connection conductor pads of the IC chip and the conductor pattern on the substrate side are connected with metal wires, and tC sealing is performed in a completely separate process. was.

I\1 The problem that the invention aims to solve Conventionally, metal wires have been used to connect IC pads and conductor patterns on substrates, but the conditions for bonding between pads, etc. and wires are permissible. narrow range, IC
Since the conditions differ depending on the substrate, it is difficult to set the bonding conditions, and bonding the wires one by one is not efficient. However, the efficiency of mounting an IC chip onto a circuit board has been low.The present invention aims to improve the efficiency of mounting such an IC chip onto a circuit board.

21 Means for Solving Problems Recently, an anisotropically conductive adhesive sheet has been developed. This material is a sheet-like material that can be used to bond two objects together by sandwiching them between the two objects and applying heat and pressure.
Moreover, it has anisotropic conductivity, having conductivity in the thickness direction and no conductivity in the direction perpendicular to the thickness, that is, in the direction in which the sheet spreads.

The present invention simultaneously completes the connection and sealing of the IC chip to the circuit pattern in one step by placing the IC chip at a predetermined position of the circuit pattern via the anisotropically conductive adhesive sheet and applying heat and pressure. I did it like that.

The anisotropically conductive adhesive sheet has conductivity in the thickness direction as shown by the arrow in Figure 1, but it is an insulator in the direction parallel to the sheet surface, so as shown in Figure 1. two objects A and B
Two objects A and B are made by heating and pressing the sheet C between them.
When bonding the two objects A and B, the mutually opposing conductor patterns a1 and bl and a2 . b2 are electrically connected by sheets C, but the pair of al, bl and a2
．． The pair b2 remains insulated by the lateral non-conductivity of sheet C. In other words, the circuit patterns bl, b2 on the object B side and the conductor patterns at, a2 on the object A side are
The process of gluing A to B connects them all at once, and the two objects A and B are electrically connected by the adhesive properties of sheet C. The sealing is completed at the same time as the number of conductor patterns to be interconnected. It is easily understood that the arrangement, shape, etc. are arbitrary.

As shown in Fig. 2, the example anisotropically conductive adhesive sheet has conductive particles m dispersed in a synthetic resin matrix P, and when compressed in the vertical direction, the particle spacing in the thickness direction is reduced. The conductive particles and the upper and lower pressure bodies contact each other in the layer thickness direction of the resin P, and electrical continuity is obtained between the upper and lower pressure bodies, but there is no conductivity in the direction perpendicular to the layer thickness. Since the distance between the conductive particles is not compressed, contact between the conductive particles does not occur, and no conductivity occurs. As the conductive particles, carbon fibers (short ones), Ni, Au, metal fine particles such as solder are used, and the particle size is mainly about several tens of μm, but particles of several μm can be mixed in. The thickness of the adhesive sheet is several tens of microns.
It is about 100 μm from m. The spacing between adjacent conductor patterns that should be mutually insulated is determined by the diameter of the conductive particles used, and when the particle diameter is 10 μm, the spacing between the conductors is 25 μm.
~100 μm 1 The thickness of the adhesive sheet is about 20 μm. In order to obtain a moisture-resistant effect by sealing the IC chip, the thicker the adhesive sheet, the better, and it is usually desirable to have a thickness of about 200 to 500 μm. In order to increase the thickness of the adhesive sheet (and reduce the insulating distance between adjacent conductor patterns), conductive fiber wires are mixed into the resin base material parallel to the thickness direction (Fig. 3). An anisotropically conductive adhesive sheet as shown in the figure is used. In this figure, P is a resin and f is a conductive fiber. Any conductive fiber wire can be used, but precious metals or common metals can be used. If a material coated with a noble metal is used, the durability of electrical contact with the pad surface can be improved.

Figures 6A and 6B show examples of anisotropically conductive adhesive sheets used in this example, and Figure 6A shows conductive wires f placed in the thickness direction in a base material sheet P that exhibits softening adhesive properties when heated. The conductive wire f is buried in a resin sheet P with both ends thereof exposed on both the upper and lower surfaces of the resin sheet P, and an adhesive layer H is provided on the surface thereof. This adhesive layer may be prepared in advance with a layer of thermoplastic resin that exhibits adhesive properties by softening when heated, or it may be used as a separate sheet and then layered and heated and pressed when mounting the IC chip. Alternatively, in the mounting process, an adhesive may be applied to the surface of the IC or the surface of the sheet 2 and bonded under pressure.

FIG. 4 shows the IC chip mounted on the substrate. B
is a circuit board, and L is a conductor pattern on the board.

K is an insulating coverlay that covers the conductor pattern, and the coverlay is removed only from the part of the conductor pattern that is connected to the IC. ICh<IC chip, the IC pattern has passivation 10 (insulating film) except for the connection pad F.
covered with. Insulating coat 2 on the circumferential side of the IC chip
0 is applied. C is an anisotropic conductive adhesive sheet,
m is a conductive particle. When pressurized, the base resin of the adhesive sheet bulges around the periphery, achieving a sealing effect around the IC.

The embodiment shown in FIG. 5 is an example in which a part of the board B for mounting an IC is punched out, and a conductor pattern L to be connected to the IC is arranged around it, and an anisotropically conductive adhesive sheet C is used to attach the IC.
The circuit connection between C and the board 8 and the entire surface of the ICC chip are being corrected.

G. Effect: The method of the present invention completes the connection and sealing of the IC chip by simply interposing an anisotropically conductive adhesive between the IC chip and the substrate and crimping it. The workability of the loading process is significantly improved.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view in the thickness direction for explaining the method of the present invention, FIG. 2 is an enlarged cross-sectional view of an anisotropically conductive adhesive sheet, and FIG.
The figure is an enlarged cross-sectional view of another type of anisotropically conductive adhesive sheet.
5 is a cross-sectional view of another embodiment of the present invention, and FIG. 6 is an enlarged cross-sectional view of yet another type of anisotropically conductive adhesive sheet. Agent Patent Attorney Hiroshi Agata III Figure Δ jlZ Figure

Claims (1)

[Claims] An IC chip is mounted on a board on which the IC chip is mounted, with the IC pads and conductor patterns to be interconnected facing each other, and an anisotropically conductive adhesive is interposed between the IC chip and the board to bond them together. A structure for mounting an IC chip onto a substrate, which is characterized by adhesive bonding.