JPH057866B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for electrically connecting a substrate having a conductive pattern and a semiconductor element such as an integrated circuit, and particularly to a method for reliably connecting a substrate at once on a substrate. It was made so that it could be done.

[Conventional technology]

Conventional electrical connection methods for mounting integrated circuits etc. on a substrate with a conductive pattern include pressure bonding, adhesion using conductive paste or conductive adhesive, connection using wire bonding, connection using film carrier, adhesion using flip-chip, etc.
Adhesion using anisotropically conductive materials was used.

Bonding using crimping, conductive paste, or conductive adhesive involves placing an integrated circuit on a conductive pattern and crimping it while applying heat or ultrasonic waves, or connecting it with a conductive paste such as solder. In this method, an electrode of a semiconductor element placed at a predetermined position on a substrate having a conductive pattern and a connection pad of the conductive pattern are crimped and connected using a wire made of gold or aluminum wire.

Connection using a film carrier uses a film having bumps formed at predetermined intervals as a carrier to transfer the bumps onto a substrate, and electrical connection is made face-down to electrodes of a semiconductor device through the bumps. Yes (refer to Japanese Patent Application Laid-Open No. 60-92648).For flip chip connection, a solder ball is formed on the electrode pad of the LSI chip, and soldered face-down to the connection pad on the board with a conductive pattern through the solder ball. This is the way to do it. These methods have the advantage that connection pads can be formed not only around the semiconductor device but also inside it, and that the connections are mechanically strong.

Connections using anisotropically conductive materials are made by sandwiching an anisotropically conductive film in which metal particles (e.g., solder, etc.) are mixed into an insulating film such as resin between a semiconductor element and a substrate having a conductive pattern, and then energizing both. It is used to make electrical connections.

[Problem that the invention seeks to solve]

However, each of the above techniques has the following problems.

Adhesion using pressure bonding, conductive paste, or conductive adhesive has problems in that reliability is low and that the connection pitch resulting from the spacing between conductive patterns is close to the limit of approximately 300 μm, making it impossible to miniaturize the device.

Bonding by wire bonding involves bonding for each electrode, so as the number of bonding points increases, the work time increases proportionally, and there are problems such as the connection pitch being limited to about 90 to 100 .mu.m.

Connections using film carriers and flip chips provide strong electrical connections, but require a large number of steps to connect, and since the electrodes of the semiconductor element are connected face-down (with the element surface facing downwards), the finished product may not be as good. There are problems such as a decrease in yield, an increase in the cost of the device, and a limit on the connection pitch of about 250 μm and about 100 μm, respectively.

Connections using anisotropic conductive materials are used for large currents because connecting an anisotropic conductive film to an integrated circuit can cause damage to semiconductor elements such as integrated circuits, and generate heat if the current density becomes too high. There were some problems, such as it being difficult to do so.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrical connection method that allows accurate electrical connections to be made on a conductive pattern on a substrate and to keep manufacturing costs low, in order to eliminate these problems. be.

[Means and actions for solving problems]

In the present invention, a plurality of metal protrusions are formed at electrical connection points of a substrate having a conductive pattern on the upper surface, and electrical connection is made through the metal protrusions.

By providing a plurality of conductive protrusions at the connection point to make electrical connection in this way, the connection can be made reliably even if there is some imperfection in the parallelism between the substrate and the semiconductor element such as an integrated circuit. I can do it.

〔Example〕

First, the principle of the present invention will be explained based on FIGS. 1 and 2.

In FIG. 1, 1 is a substrate having a conductive pattern, 2 is a connection pad on the conductive pattern, 3 is a conductive protrusion, and 4 is a semiconductor element that requires electrical connection, such as an integrated circuit element. 5 indicates the electrode portion.

First, as shown in FIGS. 1a and 1b, conductive protrusions 3 are formed in the height direction on a connection pad 2 on a substrate 1 having a conductive pattern on its upper surface by a metal forming process such as electrolytic or electroless plating. Form multiple pieces. Then, as shown in FIGS. 1c and d, after positioning the electrode 5 and the connection pad 2 on the substrate 1 with the surface of the semiconductor element 4 facing down, electrical connection is made by crimping or alloying.

Moreover, as shown in FIGS. 2a and 2b, the conductive protrusions 3
After forming, a resin film 6 such as a polymer is coated or dispersed on the surface of the protrusion, and as shown in FIG.
Connections can also be made to the semiconductor element 4. In this case, the resin acts as an adhesive, and at the time the electrical connection is made, the resin 6 on the conductive protrusion 3 flows and does not interfere with the electrical connection.

Several embodiments of the invention will be described with reference to FIGS. 3-8.

The same reference numerals in the figures represent the same parts.

FIG. 3 shows a first embodiment of the present invention, in which the left figure is a plan view of a part of the substrate 1, and the right figure is a plan view of a part of the substrate 1.
A cross-sectional view of C' (illustrated in a) is shown, in which 7 is a photoresist, 8 is an opening in the photoresist, and 9 is a resin ball.

(1) First, an opening 8 is formed in the photoresist 7 by photolithography at a predetermined position on the connection pad 2 on the substrate 1 having a conductive pattern on the upper surface. In this case, for example, a 100 μm square connecting pad 2
It shows a structure with five openings each having a diameter of 20 μm at the top [Figure 3a].

(2) Next, nickel or gold was grown to a height of about 5 μm as a conductive protrusion 3 in the opening 8 of the connection pad 2 using electrolytic plating technology [Fig. 3b].

(3) A resin with low viscosity was placed on the surface of the substrate 1 as a thermoplastic resin film 6 using a dip, and was applied so that the thickness of the coating film was uniform and thin by applying centrifugal force due to spin. [Figure 3c].

(4) Next, a thermoplastic resin ball 9 with a diameter of about 5 μm is placed in the gap between the conductive protrusions 3 on the connection pad 2. If this is simply dispersed, it can be sufficiently moved laterally if pressure is applied, and there is no problem even if it flows into areas other than the connection pad 2 (Fig. 3d).

(5) Align the connection point on the connection pad 2 of the substrate 1 with the electrode 5 of the semiconductor element 4 such as an integrated circuit facing down, and then heat-press it, and then cool it while applying pressure to complete the connection. do. At the time of thermocompression bonding, the applied resin film 6 and resin spheres 9 melt and cause damage between the substrate 1 and the semiconductor element 4, or between the substrate 1 and the conductive protrusion 3, or between the conductive protrusion 3 and the semiconductor element 4 which is a connected member. The space between the two is covered with a resin film 9' having further improved adhesion. Note that 9'' indicates air bubbles that remain after crimping [Fig. 3e].

In this embodiment, after the conductive protrusions 3 are formed, the resin film 6 is
Although the resin bulb 9 is arranged on the connection pad 2, the present invention is not limited to this.
After coating, the thermoplastic resin sphere 9 is connected to the semiconductor element 4 by thermocompression bonding or the like (see Fig. 4), or conversely, the thermoplastic resin sphere 9 is placed directly without applying the resin film 6 (Fig. 5a). A similar effect can be obtained even if the element 4 is connected (FIG. 6b).

Further, after forming the conductive protrusions 3, without applying the resin film 6 or arranging the thermoplastic resin balls 9, a pressure jig is used on the semiconductor element 4 so that pressure is constantly applied between the two, and contact connection is made by crimping. It is also possible to do this (Figure 6).

In the previous embodiment, an example was explained in which nickel or gold was used as the material for the conductive protrusion 3.
After forming the conductive protrusions 3, a coating made of a material that easily alloys with the electrodes 5 of the semiconductor element 4, such as aluminum, is formed on the surface thereof, and when an electrical connection is formed between the two, the semiconductor element is formed on the surface of the conductive protrusions 3. 4 For example, a portion 3' alloyed with an aluminum electrode of an integrated circuit may be formed [Fig. 7a], or the conductive protrusion 3 itself may be formed of a material capable of forming an alloy [Fig. 7b] ].

Although the shape of the conductive protrusion was explained as being cylindrical in the above embodiment, the present invention is not limited to this.
As shown in FIG. b-3, the substrate 1 is formed into an atoll shape and has a thermoplastic resin sphere 9 interposed in the center thereof.
It is also possible to improve the adhesiveness between the connecting member 4 and the connected member 4.

〔Effect of the invention〕

According to the present invention, since a connection is made to a semiconductor element, which is a connected member, through a plurality of conductive protrusions provided on a conductive pattern of a substrate, the connected member is connected to a substrate whose surface is not necessarily parallel. In any case, there is an effect that the connection is reliably performed by any one of the protrusions, and reliability increases as well as mechanical strength.

In addition, there is no risk of damage to the semiconductor element due to contact between the substrate and the semiconductor element, and it is a relatively short process that uses conventional technology without using complicated processes such as transferring connection bumps as in the film carrier method. Since the connection is performed in a single step, the working time can be shortened and the cost of the entire device can be kept low.

Furthermore, the connection pitch can be shortened to, for example, about 100 μm, which facilitates miniaturization of the device.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams explaining the principle of the present invention;
The figures are process explanatory diagrams of the first embodiment of the present invention, and Figs.
FIG. 8 shows other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Connection pad, 3... Conductive protrusion, 4... Semiconductor element, 5... Electrode, 6... Resin film, 9... Resin ball.

Claims (1)

[Claims] 1. In a method for electrically connecting a substrate having a conductive pattern and an electrode portion of a semiconductor element,
A substrate characterized in that a plurality of conductive protrusions smaller than the area of the area are formed in an electrical connection area on the substrate, and electrical connection is made by overlapping electrode portions of connected members via these protrusions. Electrical connection method with semiconductor elements.