JPH09293759A - Semiconductor device mounting method and circuit mounting board used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a bare chip mounting method which can be carried out independent of bumps that are not uniform in height. SOLUTION: Bumps 9 provided onto the connection terminal 4 of a semiconductor device 1 are formed of a conductive material which is easily plastically deformed so as to eliminate the influence of a lack of uniformity in their height. When the semiconductor device 1 is pressed down against a circuit mounting board 2, the high bumps 9 are deformed, so that the low bumps 8 can be bonded enough. Uncured thermosetting resin or photosetting resin 10 is used so as to firmly bond the device 1 and the circuit mounting board 2 together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor device on a circuit board.

[0002]

2. Description of the Related Art In recent years, laptop computers, mobile phones, PH
There is an increasing need for high-density mounting in mobile information terminal devices such as S and PDAs, and mobile video devices such as movies and cameras. In order to cope with this, the so-called bare chip mounting method in which the element is directly mounted on the substrate is becoming the mainstream for mounting the semiconductor element from the conventional method for mounting the packaged product.

Conventionally, as a method for directly mounting a semiconductor element on a circuit board, (1) a semiconductor element is first bonded face-up to a substrate, and then a connection terminal of the board and a connection terminal of the semiconductor element are made of gold or aluminum. (2) Wire bonding method for connecting with wires (2), (2) A semiconductor element having solder bumps formed on connection terminals is mounted face down on a substrate and then connected by reflow. Finally, a method of filling a resin between the semiconductor element and the substrate (Fig. 2), (3) Attaching an anisotropic conductive film (having conductive particles dispersed in resin) to the substrate, and then connecting terminals There is a method (FIG. 3) of face-down thermocompression bonding of a semiconductor element on which gold bumps are formed.

[0004]

Among the above-described semiconductor mounting methods on a circuit board, the wire bonding method (1) is a technique established by a proven method for inner lead bonding of a semiconductor package. Since it is necessary to provide the connection terminals on the outside of the mounting area of the semiconductor element on the substrate, the actual occupied area becomes large, which is inferior to the other two methods in terms of high-density mounting. Also,
The solder bump method of (2) has a problem that a man-hour for mounting is required because resin filling is required between the semiconductor element and the substrate for ensuring reliability, and solder is used as a connecting member. Therefore, there is a drawback that it is not possible to cope with a narrow connection pitch and connection of a multi-pin semiconductor element. The anisotropic conductive film method of (3) has a small mounting man-hour, a narrow connection pitch,
Although this method can be applied to the connection of multi-pin semiconductor elements, there is a problem that it is difficult to connect all the bumps uniformly when the height variation of the gold bumps formed on the semiconductor element is large.

[0005]

The method of the present invention devised to solve the above-mentioned problems of the conventional method is as follows: (1) First, a bump is formed on a connection terminal of a semiconductor element with a conductive material that can be easily plastically deformed. (FIG. 4 (a)).

(2) Next, an uncured thermosetting resin or its film or a photo-curing resin is supplied to the connection terminal portion on the substrate (FIG. 4 (b)).

(3) The semiconductor element and the substrate are aligned and then thermocompression bonded (FIG. 4 (c)).

In this method, (1) the occupied area on the substrate required for mounting is only the area corresponding to the size of the semiconductor element, and high-density mounting is possible as compared with the conventional wire bonding method. Also, the mounting man-hour is smaller than that of the conventional solder bump method. Further, the connection pitch can be made smaller than that of the solder bump method. Also. By forming the bumps with a conductive material that can be easily plastically deformed, there is an advantage that defects due to bump height variations, which are problems of the conventional anisotropic conductive film method, do not occur.

The conductive material which can be easily plastically deformed for use in the present invention includes (1) flexible metal such as indium, lead (FIG. 5 (a)), and (2) metal coated plastic (FIG. 5). (b)), (3) a conductive adhesive containing a thermoplastic resin as a binder (FIG. 5 (c)), and (4) a conductive polymer (FIG. 5 (d)) can be used. Flexible metal bumps such as indium are manufactured by plating and photolithography processes. For a plastic bump with a metal film, first, a metal film such as gold is deposited on the element connection terminals by patterning by a film forming method such as vapor deposition, sputtering, plating, etc. and a photolithography method, and then a plastic film is formed on a part of the metal film. To do. Finally, electroless plating is performed to form a metal film on the entire surface of the plastic. The conductive adhesive bumps using the thermoplastic resin as a binder and the conductive polymer bumps are pattern-formed on the element connection terminal portion by high-precision printing.

Generally, since the total area of the connection bumps is extremely smaller than the area of the semiconductor element, it is difficult to simply thermocompress the semiconductor element and the circuit board and secure the connection reliability only by the bonding force of the bump portion. Therefore, in the present invention, in order to firmly bond the semiconductor element on which the bump is formed and the circuit board, the element and the board are bonded with resin. To obtain sufficient connection reliability, a thermosetting resin such as an epoxy resin or a photocurable resin such as an acrylic resin is used as this resin. A thermoplastic resin has a large coefficient of thermal expansion and a large water absorption, so that sufficient connection reliability cannot be obtained. As a form of using these resins, a liquid resin can be supplied to the substrate connecting terminal portion by a dispenser or the like, but using a film-shaped uncured resin is superior in workability.

Bonding is performed by a pressure bonding method. When an uncured thermosetting resin is used, heating and pressing are performed simultaneously by using a heated pressing head. When a photo-curable resin is used, ultraviolet rays are radiated from the gap between the element and the substrate when applying pressure. In the case of a glass substrate, ultraviolet rays are emitted from the back surface of the substrate.

According to the connection method of the present invention, when a semiconductor element having a bump height variation is connected by a material, a load is first applied to a bump having a high height, but the bump is easily deformed. Even if there are low bumps, there is no connection failure (FIGS. 6A, 6B, 6C, and 6D), and bare chip mounting is possible with high yield.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments.

[Example 1] The members used are described below.

Semiconductor device: The device size is 4.0 × 4.
0 mm, connection terminal size 80 × 80 μm, pitch 1
It was 30 μm.

Circuit board: Glass was used as a board material, and ITO was used as a connection terminal and a wiring material. The size and pitch of the connection terminals were the same as those of the semiconductor element.

The wiring between the element and the substrate was designed so that the connection resistance could be measured by the 4-terminal method. Indium bumps were formed on the connection terminals of the semiconductor element by sputtering and photolithography. The height of the indium bumps was 29 μm on average. The maximum bump height is 36μ in one device.
m, and the minimum value was 25 μm. An uncured epoxy resin film having a thickness of 30 μm was attached to the connection terminal portion of the circuit board. Next, after aligning the element and the substrate,
It was thermocompression bonded for 30 seconds at a temperature of 200 ° C. and a load of 50 MPa.
As a result, a bump connection resistance of 2 mΩ or less was obtained.

[Example 2] The same members as in Example 1 were used. Gold was formed on the connection terminal portion of the semiconductor element by a sputtering or photolithography method. Next, a photo-curable low-elasticity resin was formed on a part of the gold film by a photolithography method. Next, a portion other than the connection terminal portion was protected with a resist to form an electroless nickel plating film only on the surface of the low elasticity resin. The height of the entire bump was 23 μm on average. The maximum value of the bump height was 28 μm and the minimum value was 21 μm in one element. An uncured photocurable resin having a thickness of about 25 μm was applied to the connection terminal portion of the circuit board. Next, after aligning the element and the substrate, from the back surface of the substrate, 20 mW / cm ²
While irradiating the ultraviolet ray having the intensity of (wavelength 365 nm), the pressure was applied for 60 seconds under a load of 100 MPa. With this, 10m
A bump connection resistance of Ω or less was obtained.

[Example 3] The same members as in Example 1 were used. Silver paste containing urethane resin as a binder was printed on the connection terminals of the semiconductor element. 10 degrees Celsius
It was dried at 0 degrees for 1 hour. Average height of bumps is 3
It was 6 μm. The maximum value of the bump height in one device was 45 μm, and the minimum value was 23 μm. On the other hand, an uncured epoxy resin film having a thickness of 45 μm was attached to the connection terminal portion of the circuit board. Next, after aligning the element and the substrate, 30 degrees Celsius and a load of 40 MPa are used.
It was heated and pressed for seconds. As a result, a bump connection resistance of 2 mΩ or less was obtained.

[Example 4] The same members as in Example 1 were used. A polyaniline film doped with camphorsulfonic acid was formed on the connection terminal portion of the semiconductor element by a photolithography method. The height of the entire bump was 21 μm on average. The maximum bump height is 26μ in one device.
m, and the minimum value was 19 μm. An uncured photocurable resin having a thickness of about 20 μm was applied to the connection terminal portion of the circuit board. Next, after aligning the element and the substrate, pressure was applied for 60 seconds under a load of 20 MPa while irradiating ultraviolet rays having an intensity of 20 mW / cm ² (wavelength 365 nm) from the back surface of the substrate. As a result, a bump connection resistance of 10 mΩ or less was obtained.

[0021]

According to the present invention, it is possible to solve the problems of the conventional method in a bare chip mounting method for directly mounting a semiconductor element on a circuit board, and to achieve high density, high yield, and short steps of the element. Can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a conventional wire bumping method.

FIG. 2 is an explanatory diagram showing a conventional solder bump method.

FIG. 3 is an explanatory view showing a conventional anisotropic conductive film method.

FIG. 4 is an explanatory diagram showing a mounting method of the present invention.

FIG. 5 is an explanatory diagram showing a bump structure of the present invention.

FIG. 6 is an explanatory view showing a bump connection structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor element, 2 ... Circuit board, 4 ... Connection terminal of circuit board, 9 ... Bump formed by the conductive material which can be easily plastically deformed, 10 ... Unhardened thermosetting resin or photocurable resin.

Claims (6)

[Claims] 1. A semiconductor element having a bump formed with a conductive material which is easily plastically deformed on a connection terminal portion and a circuit board are subjected to thermocompression bonding or ultraviolet irradiation with an uncured thermosetting resin or photocurable resin interposed. A method for mounting a semiconductor element, characterized in that they are connected by joint crimping. 2. The method for mounting a semiconductor element according to claim 1, wherein the conductive material is a metal selected from indium and lead. 3. The method for mounting a semiconductor element according to claim 1, wherein the conductive material has a structure in which a metal film is formed on plastic. 4. The method for mounting a semiconductor element according to claim 1, wherein the conductive material is a conductive adhesive containing a thermoplastic resin as a binder. 5. The method for mounting a semiconductor element according to claim 1, wherein the conductive material is a conductive polymer. 6. A circuit mounting board, wherein a semiconductor element having bumps formed of a conductive material that is easily plastically deformed on a connection terminal portion is bonded to a circuit board with a photocurable resin or a thermosetting resin.