JPH0927515A - Semiconductor mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor mounting method capable of obtaining the improved electric conduction of a semiconductor element on a mounting circuit substrate by uniform external-pressure connection in a semiconductor mounting field in a semiconductor package or a semiconductor module (for instance, a multichip module). SOLUTION: In a mounting method of electrically connecting a gold bump or a surface layer gold bump formed on the electrode of a semiconductor element 3 to a wiring connection part formed on a mounting circuit substrate 1, the semiconductor element 3 is temporarily fixed on the mounting circuit substrate 1 and after that, electric conduction is obtained by utilizing uniform shrinkage force from the outside of a tube-like thermal contractive molding body 8 containing a polycarbodiimide resin as a main component. The exchange and the replacement of the semiconductor element 3 can be easily and repeatedly performed by using the thermal contractive molding body 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in the field of semiconductor mounting in a semiconductor package or a semiconductor module (for example, a multi-chip module), obtains good electrical continuity by uniform external pressure connection of semiconductor elements on a mounting circuit board. The present invention relates to a semiconductor mounting method that makes it possible. A more preferable aspect relates to a semiconductor mounting method that allows easy exchange and replacement of semiconductor elements.

[0002]

2. Description of the Related Art As a semiconductor mounting method, a wire bonding method using metal bonding, a TAB method, and a flip chip method using solder bumps are known.
Since the solid phase diffusion mechanism or the solid phase-liquid phase reaction mechanism is used, the bonding temperature is generally in a high temperature region of 200 ° C. or higher, and a semiconductor element having a fine line width is likely to be damaged by thermal stress. There is a potential problem. Further, since these metal joints are permanent joints, a defective semiconductor element cannot be replaced when a connection failure occurs.

Further, in the metal joining method, IT of the liquid crystal display panel is used.
Since a semiconductor element cannot be mounted on an O (indium titanium oxide) transparent electrode, an anisotropic conductive film or a resin bonding method in which conductive particles are mixed is recently used as a mechanical bonding method. Since these methods are used by filling a thermosetting or photo-curable resin between the semiconductor element and the mounting substrate, conduction failure is likely to occur due to a decrease in adhesive strength due to deterioration of the resin over time. There is a drawback in that conduction failure is likely to occur due to partial peeling due to thermal stress or mechanical external stress. further,
In these methods, since a thermosetting or photocurable resin is filled between the semiconductor element and the mounting substrate, it is difficult to replace the defective semiconductor element, and there is a problem in replacement and replaceability.

[0004]

SUMMARY OF THE INVENTION The present invention is different from the conventional one for the purpose of permanent bonding by metal bonding method or resin bonding method, and is preferable for uniform external pressure connection of semiconductor elements on a mounting circuit board. It is an object of the present invention to provide a semiconductor mounting method capable of obtaining excellent electrical continuity, and a more preferable aspect is to provide a semiconductor mounting method capable of easily and repeatedly exchanging and exchanging semiconductor elements.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve the problems of the prior art, the inventors of the present invention have electrically mounted semiconductor elements such as IC, LSI and VLSI on a mounting circuit board. After temporary fixing for connection positioning, the tube-shaped heat-shrinkable molded article containing polycarbodiimide resin as a main component is coated from the outer peripheral portion, and the molded article is first shrunk by heating at 120 ° C. or lower, The contraction force provides electrical continuity between the semiconductor element and the mounting circuit board, and by further thermosetting this into a permanent-cured molded body film, a semiconductor mounting method with excellent reliability such as heat resistance and moisture resistance is provided. It was found that the present invention has been completed.

That is, the present invention is a mounting method for electrically connecting a gold bump or a surface layer gold bump formed on an electrode of a semiconductor element and a wiring connection portion formed on a mounting circuit board to mount the semiconductor element. A semiconductor mounting method characterized in that, after being temporarily fixed on a circuit board, electrical conduction is obtained by utilizing a uniform shrinking force from the outside of a heat-shrinkable molded body containing a tubular polycarbodiimide resin as a main component. The adhesive may be an ordinary adhesive as a temporary fixing means, but it is preferable to temporarily fix the bump and the wiring connecting portion with a conductive adhesive. Further, the conductive adhesive is more preferably composed of a conductive material such as metal powder or metal plated resin balls and a thermoplastic adhesive resin such as ethylene-vinyl acetate copolymer, polyamide, polyacrylate, polyester or polyurethane.

Next, the present invention will be specifically described with reference to the drawings. FIG. 1 is a perspective view showing a state in which a semiconductor element is temporarily fixed on a mounting circuit board, and FIG. 2 is a sectional view taken along the line AA ′ of FIG.
In the upper wiring connection portion (connection terminal) 2, a gold bump provided on the electrode 4 of the semiconductor element 3 or a surface gold bump 5 having a metal such as copper or nickel as a core is electrically connected by a conductive adhesive 6. Temporarily fixed to align the connection. 7
Indicates a circuit pattern. FIG. 3 is a cross-sectional view showing a state in which the unit in which the semiconductor element is temporarily fixed on the mounting circuit board as shown in FIG. 2 is loaded in the tubular heat-shrinkable molded body 8 whose main component is polycarbodiimide resin. 4 is a cross-sectional view showing a semiconductor mounting state in which the above-mentioned tube-shaped heat-shrinkable molded body 8 is heated and brought into close contact with the unit, and further, this is thermally cured to form a permanent-cured molded body film. In the above description, one semiconductor element is mounted on the mounting circuit board, but a plurality of semiconductor elements may be mounted.

The tube-shaped heat-shrinkable molded article containing the polycarbodiimide resin as the main component used in the present invention is as follows:
A solution obtained by adding a colorant, a filler, etc. to a polycarbodiimide resin as needed is formed into a film by a known method (for example, a casting method), and then uniformly stretched to 150 to 400% at a temperature of 40 to 120 ° C to be heat-shrinkable. A film is produced, and the film is processed into a tube shape to obtain a heat-shrinkable tube. Alternatively, the film may be first processed into a tube or a tube-shaped film may be prepared, and then stretched by a known method such as a tubular stretching method. The film can be processed by a method such as heat sealing. When processing into a tube shape, the size when completely contracted is 1 more than the size of the mounting circuit board.
It is preferable to design so as to be reduced by about 0 to 50%. The area of the tube before contraction is preferably 10 to 50% larger than that of the mounted circuit board.

Next, the mounted circuit board on which the semiconductor element is temporarily fixed is loaded into the heat-shrinkable molded body (tube), and 4
Heat to 0-120 ° C. At this time the tube shrinks,
It is in close contact with the mounting circuit board and is temporarily sealed. At this point, the tube is not completely bonded to the mounted circuit board, so if a defective semiconductor element is found as a result of the continuity test, the defective semiconductor element can be replaced by cutting the tube. If the result of the continuity test is good, the heat-shrinkable mounted circuit board that has been temporarily sealed is further added to 150 to 30.
By subjecting the polycarbodiimide resin to a heat treatment at 0 ° C., preferably 200 to 250 ° C. for 1 minute to 2 hours, preferably 5 minutes to 1 hour, the polycarbodiimide resin is crosslinked and cured to form a highly reliable permanent cured film. Become. The sealing is completed by the above operation, and the film protects the entire semiconductor mounting substrate.

[0010]

According to the semiconductor mounting method of the present invention, when the gold bumps or surface layer gold bumps formed on the electrodes of the semiconductor element and the wiring connecting portions formed on the mounting circuit board are electrically connected, After the element is temporarily fixed on the mounting circuit board, the semiconductor element is connected because it is a connection method by external pressurization to obtain electrical continuity by utilizing the uniform shrinking force from the outside of the tubular heat-shrinkable molded body. Even if the size is increased, uniform pressurization is possible, and there is a feature that connection failures are less likely to occur. In addition, since the polycarbodiimide resin is used as the tube-shaped heat-shrinkable molded product, the molded product coating can be easily removed from the circuit board in the state before cross-linking and curing, so it is also possible to attach and detach and replace the semiconductor element. It is possible and economically superior. Furthermore, the molded film after cross-linking and curing can be used as a coating material for protecting the external environment, and high reliability such as moisture resistance can be obtained.

[0011]

EXAMPLES Next, the present invention will be specifically described by way of examples. In the following text, "parts" means "parts by weight". Example 1 10 parts of 4,4'-diphenylmethane diisocyanate in 100 parts of toluene together with 0.06 part of a carbodiimidization catalyst (3-methyl-1-phenylphosphorene).
The reaction was carried out at 0 ° C for 6 hours to obtain a polycarbodiimide resin solution. Cast this solution onto a glass plate and
Dry for 20 minutes with a hot air dryer at 10 ° C to a thickness of 70μ
A polycarbodiimide film of m was obtained. This film was stretched twice at 80 ° C, cooled to room temperature in that state to form a heat-shrinkable film, then formed into a tube having a diameter of 3.5 cm, and the ends were joined with a heat sealer, followed by heat treatment. A shrinkable tube was made.

This heat-shrinkable tube was cut into a length of 4 cm, and a semiconductor element having 120 mushroom-type gold bumps was made into a conductive adhesive (ethylene-vinyl acetate copolymer resin in which nickel particles having a diameter of 10 μm were dispersed). ), The ceramic circuit board of 4 cm × 4 cm and 3 mm in height temporarily fixed to the wiring connection part is loaded into the tube, and heated at 100 ° C. for 2 minutes to shrink the tube to completely adhere the film surface to the circuit board. It was In addition, this circuit board
The film was cured by heating at 1 ° C for 1 hour to obtain a permanent cured film. As a result of evaluating the connection characteristics of the semiconductor element of this circuit board, good electrical conduction was obtained, and no conduction failure due to peeling occurred. Also, regarding this substrate, 150
A high temperature storage test was performed at 1000C for 1000 hours, but no change was observed in the film.

Example 2 A heat-shrinkable tube was prepared in the same manner as in Example 1,
A ceramic circuit board of the same size to which a semiconductor element was temporarily fixed was loaded as in Example 1, and heated at 100 ° C. for 2 minutes to shrink the tube, and the film surface was brought into complete contact with the circuit board. Here, as a result of evaluating the connection characteristics of the semiconductor element,
This semiconductor element was found to be defective. Then, the film is cut with a cutter and removed, and the film of Example 1 is again used.
Using the heat-shrinkable tube, the film surface was brought into complete contact with the circuit board in the same manner as in. As a result of evaluating the connection characteristics and peeling of the semiconductor element of this circuit board, good electrical conduction was obtained, and no conduction failure due to peeling occurred. Then, this substrate was heat-treated at 230 ° C. for 1 hour to cure the film, thereby forming a permanent cured film. About this substrate 150 ℃
After conducting a high temperature storage test for 1000 hours, no change was observed in the film.

Comparative Example 1 Instead of the polycarbodiimide resin of Example 1, a polypropylene heat shrinkable tube having a diameter of 3.5 cm was used. This heat-shrinkable tube was cut into a length of 4 cm, a ceramic circuit board of the same size in which a semiconductor element was temporarily fixed was loaded in the same manner as in Example 1, and the tube was shrunk by heating at 100 ° C. for 2 minutes to form a film. The surface was completely attached to the circuit board. As a result of evaluating the connection characteristics and peeling of the semiconductor element of this circuit board, good electrical conduction was obtained, and no conduction failure due to peeling occurred. However, about this board 15
When a high temperature storage test was performed at 0 ° C., the film deteriorated within several hours.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a unit in which a semiconductor element is temporarily fixed on a mounting circuit board according to the present invention.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1 and viewed in the direction of the arrow.

FIG. 3 is a cross-sectional view showing a state in which the unit in which the semiconductor element of FIG. 2 is temporarily fixed on a mounting circuit board is loaded into a tubular heat-shrinkable molded body containing a polycarbodiimide resin as a main component.

FIG. 4 is a cross-sectional view showing a semiconductor mounted state in which the tube-shaped heat-shrinkable molded body of FIG. 3 is heated and brought into close contact with a unit, and further this is heat-cured to form a permanent-cured molded body film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mounted circuit board 2 Wiring connection part 3 Semiconductor element 5 Gold bump 6 Conductive adhesive 8 Tube-shaped heat-shrinkable molded body

Claims (3)

[Claims] 1. A mounting method for electrically connecting a gold bump or a surface layer gold bump formed on an electrode of a semiconductor element and a wiring connection portion formed on the mounting circuit board, wherein the semiconductor element is mounted on the mounting circuit board. After being temporarily fixed to, a semiconductor mounting method characterized in that electrical conduction is obtained by utilizing a uniform shrinking force from the outside of a tubular heat-shrinkable molded body containing a polycarbodiimide resin as a main component. 2. The semiconductor mounting method according to claim 1, wherein the semiconductor mounting method is temporary fixing with a conductive adhesive. 3. The semiconductor mounting method according to claim 2, wherein the conductive adhesive comprises a conductive material and a thermoplastic adhesive resin.