JPH06342795A - Flip chip mounting connection structure of ic - Google Patents

Abstract

PURPOSE:To obtain a flip chip mounting connection structure of an IC, wherein a micro joint is put in an electrical connection state even if cracks are generated inside bumps due to thermocompression. CONSTITUTION:The flip chip mounting connection structure of an IC is such that an IC element 1 is provided with metal electrode pads 5, and waste conductive fibers 5a or a bump 5 wherein bundled metal fibers or coiled metal fibers are enclosed is bonded to the metal electrode pad 5 by thermocompression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip-chip mounting connection structure of an IC, and more particularly to a flip-chip mounting structure of an IC which is electrically connected to a lead electrode of a substrate even if a bump is cracked during thermocompression bonding. Connection structure.

[0002]

2. Description of the Related Art With the demand for high functionality of electronic equipment, IC
Is being miniaturized. For example, "Electronic Packaging Technology (EL Electro Packaging Technology)
Noology), 1992.4 (Vol8 No4),
Flip mounting method shown in “Information Research Committee, Takashi Nukii, P29 to P35” will be described. FIG. 7 is a mounting conceptual diagram of a conventional flip chip method and another mounting method. In the figure, (a) is a flat package SMT mounting in which a metal electrode pad (hereinafter referred to as an electrode) of an IC element and a lead electrode of a substrate are connected by wire bonding. (B) is a molded TCP in which the lead electrode of the substrate and the electrode of the IC element are directly connected without wire bonding.
It is SMT mounting, and from flat package SMT,
It is miniaturized. (C) is a wire bonding COB in which the bonding of ceramics or the like is stopped and the IC element is directly wire bonded.
It is more compact than the implementation. (D) Bare chip TA
B / OLB mounting, which is smaller than wire bonding type COB mounting. (E) is a flip-chip type mounting, which can be dissolved and connected to a substrate or the like by bumps, and the mounting is the smallest in this drawing.

As described above, the mounting of IC elements tends to be miniaturized, and the pitch of the bumps thereof tends to be miniaturized. For example, three examples shown in Table 1 of the above document will be described.

[0004]

[Table 1]

In Example 1, as shown in Table 1, a conductive paste connection system was adopted. A copper bump was used as a core material on the IC chip side, and the surface of the copper bump was plated with Au to a thickness of about 5 μm. A bump having a height of 50 μm is formed, a conductive Pd-Ag paste is applied to the bonding portion (also referred to as a pad) on the Au, and the lead electrode on the glass substrate and the conductive Pd-Ag paste are used. I am trying to make an electrical connection. In Example 2, a microbump connection method is adopted, and an IC chip with bumps is aligned on a substrate onto which a photocurable resin has been dropped, and light is irradiated under pressure to cure and shrink the photocurable resin. The electrodes are electrically connected to each other.

In Example 3, the conductive particle intervening pressure welding method is adopted, in which conductive elastic particles serving as a connecting medium are mixed with an adhesive and placed on a panel electrode, and then an epoxy thermosetting adhesive is used. Then, the IC chip with the AL electrode as it is is faced down and heated and pressed to electrically connect the electrode and the bump.

However, since the minute bumps as described above are used, bumps are applied to the electrodes of the IC chip and the electrodes of the substrate (hereinafter collectively referred to as micro-joint portions) during thermocompression bonding. As the environment is changed (ambient temperature), the bumps are cracked due to the difference in coefficient of thermal expansion between the electrodes of the IC chip and the electrodes of the substrate and the electrical connection is broken. There was a point. The present invention has been made to solve the above problems, and provides a flip-chip mounting connection structure of an IC that electrically connects micro-joints even if cracks occur in bumps due to thermocompression bonding. The purpose is to

[0007]

According to the flip-chip mounting connection structure of an IC of the present invention, bumps in which conductive fibers are encapsulated are thermocompression bonded to an IC element having a plurality of metal electrode pads. It is a thing. In addition, an IC element in which a bump in which a conductive fiber is encapsulated is thermocompression bonded to a plurality of metal electrode pads is sandwiched between the bumps and thermocompression bonded to a lead electrode of the substrate. Further, the conductive fibers are at least scrap-like, net-like or coil-like or bundle-like.

[0008]

In the present invention, since bumps containing at least scrap-like, mesh-like, coil-like, or bundle-like conductive fibers encapsulated in an IC element having a plurality of metal electrode pads are thermocompression-bonded to the metal electrode pads, When thermocompression-bonded to the lead electrode of the substrate, even if a crack occurs in the bump, the metal electrode pad and the lead electrode are maintained in an electrically connected state.

[0009]

1 is a schematic structural diagram of a first embodiment of the present invention. In the figure, 1 is an IC chip, 2 is an IC electrode, 3
Is a substrate, 4 is a lead electrode on the side of the substrate, 5 is a bump of the first embodiment, and 5a is a conductive fiber of the first embodiment, which is scraped. The conductive fiber 5 of this first embodiment
For example, carbon is used as a. The conductive fiber 5a according to the first embodiment is spread over the entire bump 5. A case where a crack occurs in the AA cross section as shown in FIG. 1 in such a state will be described below. Figure 2
[FIG. 6] is an explanatory diagram when a crack is generated in the first embodiment. In the figure, 1 to 5a are the same as those in FIG. As shown in the figure, for example, when a crack is generated in the AA cross section, the conductive fiber 5a of the first embodiment is enclosed in the bump 5 in a scrap-like shape, and therefore A-A Even if a crack is generated in the cross section, an electrically connected state is secured between the electrode of the IC chip and the lead electrode of the substrate.

In this bump forming process, for example, a conventional bump is melted, scraped conductive fibers are put into the melted bump, the mixture is stirred, sucked up with a dropper, etc., taken out from the dropper, and formed into a ball shape. Get the bump of. Then, the ball-shaped bumps containing the conductive fibers are arranged on the electrodes of the IC chip and the lead electrodes of the substrate and soldered. FIG. 3 is a schematic structural diagram of the second embodiment. In the figure, 1 to 4 are the same as above. 6 is the bump of the second embodiment, and 6a is the conductive fiber of the second embodiment, which is formed into a bundle. This second
For example, carbon or the like is used as the conductive fiber 6a in this embodiment. In such a state, a case where a crack (crack) occurs in the AA cross section as shown in FIG. 3, for example, a case where a crack (crack) occurs in the AA cross section will be described below.

FIG. 4 is an explanatory view when a crack is generated in the second embodiment. In the figure, 1 to 6a are the same as those in FIG. As shown in the figure,
For example, when a crack is generated in the AA cross section, it means that the conductive fiber 6a of the second embodiment is encapsulated in a bundle in the bump 6, so that the crack is generated in the AA cross section. Also, the electrically connected state is secured between the electrodes of the IC chip and the lead electrodes of the substrate. FIG. 4 is a schematic structural diagram of the third embodiment. In the figure, 1 to 4 are the same as above. Reference numeral 7 is a bump of the third embodiment, and 7a is a conductive fiber of the third embodiment, which is coiled.
For example, carbon or the like is used for the conductive fiber 7a of the third embodiment. A case where a crack occurs in the AA cross section as shown in FIG. 4 in such a state will be described below.

FIG. 5 is an explanatory view when a crack is generated in the third embodiment. In the figure, 1 to 7a are the same as those in FIG. As shown in the figure,
For example, when a crack is generated in the AA cross section, it means that the conductive fiber 7a of the third embodiment is enclosed in the bump 7 in a bundle shape, so that the crack is generated in the AA cross section. Also, the electrically connected state is secured between the electrodes of the IC chip and the lead electrodes of the substrate. The conductive fibers are not limited to carbon fibers, but other metal fibers, metal coats, conductive glass fibers, conductive polymers (those having conductivity in the structure itself, or conductive fillers were mixed). Materials) and the like may be used. Further, the conductive fibers are not limited to be in the form of scraps or bundles, but may be in the form of nets, chains or the like.

[0013]

As described above, according to the present invention, an IC element having a plurality of metal electrode pads is provided with bumps in which at least scrap-like, net-like, coil-like, or bundle-like conductive fibers are encapsulated, and the bumps are provided with the metal electrodes. By thermocompression bonding to the pad,
Even if a crack occurs in the bump when it is thermocompression-bonded to the lead electrode of the substrate, the metal electrode pad and the lead electrode of the substrate are maintained in an electrically connected state, so that it is possible to use it as it is. Has been obtained. In addition, since the bumps are filled with metallic fibers, the electrical connection is maintained even if the thermal expansion coefficient of the lead electrode of the substrate is far from that of the metal electrode pad of the IC. The effect that it is possible is obtained.

[Brief description of drawings]

FIG. 1 is a schematic structural diagram of a first embodiment.

FIG. 2 is an explanatory diagram when a crack occurs in the first embodiment.

FIG. 3 is a schematic structural diagram of a second embodiment.

FIG. 4 is an explanatory diagram when a crack is generated in the second embodiment.

FIG. 5 is a schematic structural diagram of a third embodiment.

FIG. 6 is an explanatory diagram when a crack is generated in the third embodiment.

FIG. 7 is a mounting conceptual diagram of a conventional flip chip method and another mounting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 IC chip 2 IC electrode 3 Substrate 4 Lead electrode on the substrate side 5 Bump 5a of the first embodiment 5a Conductive fiber of the first embodiment 6 Bump 6a of the second embodiment 6a Conductive fiber of the second embodiment 7 Bumps of the third embodiment 7a Conductive fibers of the third embodiment

Claims (3)

[Claims] 1. A connection structure for flip-chip mounting of an IC, wherein bumps in which conductive fibers are encapsulated are thermocompression bonded to the metal electrode pads on an IC device having a plurality of metal electrode pads. 2. A flip of an IC, wherein an IC element in which a bump in which a conductive fiber is encapsulated is thermocompression bonded to a plurality of metal electrode pads is thermocompression bonded to a lead electrode of a substrate with the bump interposed therebetween. Chip-mounted connection structure. 3. The connection structure for flip-chip mounting of an IC according to claim 1, wherein the conductive fibers are at least scrap-like, net-like, coil-like, or bundle-like.