JPH04246839A - Ic mounting method - Google Patents

Abstract

PURPOSE:To mount the electrode pads of an IC chip on a circuit substrate using a conductive bonding agent by electrical connection method solving the problem of defect such as shortcircuit, etc., by spreading a bonding agent giving the intensive bond strength and the manhour cutting down effect during the thermosetting step. CONSTITUTION:An IC chip 1 is pressed on a circuit substrate 4 using the bump contacts 3 of electrode pads 2 on the IC chip 1 and the terminal electrodes 5 of the circuit substrate 4 as well as a conductive bonding agent 6 which is thermoset to mount the IC chip 1 on the circuit substrate 4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses a conductive adhesive to connect protruding contacts formed on input/output pads of electric microcircuit elements such as IC chips and electrode terminals formed on a circuit board. This invention relates to an IC mounting method for stable electrical connection.

0002

2. Description of the Related Art Conventionally, soldering has often been used to connect the contact area of an electric microcircuit element to an electrode terminal portion on a circuit board. However, in recent years, for example, due to the miniaturization of IC flat packages and the increase in the number of connection terminals, the distance between the connection terminals, that is, the pitch interval has become gradually narrower, making it difficult to cope with the problem using conventional soldering techniques. Recently, there has also been a movement to more efficiently use the mounting area of calculators, electronic watches, and liquid crystal displays by directly attaching bare IC chips to electrodes on glass substrates.
There has been a strong desire for an effective and fine electrical connection means to replace soldering.

[0003] A method for electrically connecting a bare IC chip to an electrode on a circuit board is to apply a conductive adhesive to the top of a conductive protruding contact formed on the electrode pad of the IC chip, and then attach it to the circuit board. There is a technique for electrically connecting an IC chip and a circuit board by aligning the electrode terminals with the electrode terminals and curing the adhesive (Japanese Patent Application Laid-Open No. 62-285446). In this conventional method, after an IC chip is mounted on a circuit board, the circuit board is placed in a separately prepared dryer to harden the conductive adhesive.

A conventional IC mounting method will be explained below with reference to the drawings. 7 to 11 show the steps in a conventional IC mounting method. In the figures, 1 is an IC chip, 2 is an electrode pad arranged on the IC chip 1 at a pitch of 150 μm, and 3 is an electrode pad on the electrode pad 2. After forming by wire bonding method using Au, approximately 4
A protruding contact formed flat with a height of 0 μm, 4 a circuit board, 5 a terminal electrode formed on the circuit board 4, 6 a conductive adhesive transferred and coated on the protruding contact 3, 7 a conductive An adhesive film, 8 an IC holding device, 9 a support, and 10 a dryer.

[0005] Next, the mounting process for the above structure will be explained. In FIG. 7, in order to transfer and apply the conductive adhesive 6 to the protruding contacts 3 of the IC chip 1, the IC chip 1 is adsorbed by an IC holding device 8 and moved onto a support 9 on which a conductive adhesive film 7 is formed, and the positioning is performed. After that, as shown in FIG. 8, the protruding contacts 3 of the IC chip 1 are bonded to a conductive adhesive film 7.
be immersed in FIG. 9 shows a state in which the conductive adhesive 6 is transferred and applied to the protruding contacts 3 of the IC chip 1.

Thereafter, as shown in FIG. 10, the protruding contacts 3 of the IC chip 1 on which the conductive adhesive 6 has been transferred and applied to the terminal electrodes 5 on the circuit board 4 are aligned and aligned with the terminal electrodes 5 on the circuit board 4. The protruding contacts 3 of the IC chip 1 are connected. Thereafter, as shown in FIG. 11, the conductive adhesive 6 is put into a dryer 10 and cured in units of several sheets in a batch manner, thereby completing the mounting.

[0007]

However, in the conventional IC mounting method described above, the conductive adhesive 6 is cured in the dryer 10 after the IC chip 1 is mounted on the circuit board 4. Since the adhesive 6 is placed in an uncured state, the connection becomes unstable, and if an external force such as vibration is applied to the circuit board 4 or IC chip 1, the IC chip 1 will come off from the terminal electrode 5 of the circuit board 4, resulting in an open state. Failures such as short circuits or short circuits occurred. In addition, if the amount of conductive adhesive 6 transferred and applied to the protruding contact 3 and connected to the terminal electrode 5 is large enough, the IC chip 1 and the circuit board 4 will be electrically connected to each other.
However, since the distance between the terminals is as narrow as 150 μm, the spread of the conductive adhesive 6 on the terminal electrode 5 is too large, causing a short circuit between the electrode terminals as shown in FIG. there were.

[0008] The present invention is intended to solve these conventional problems, and aims to provide an IC mounting method with excellent electrical connection reliability.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention applies a conductive adhesive to the protruding contacts of an IC chip, and then applies the conductive adhesive while pressing the IC chip onto a circuit board. It is cured by applying heat.

0010

[Operation] Therefore, according to the present invention, since heating starts immediately after the conductive adhesive transferred to the protruding contacts on the IC chip comes into contact with the circuit board, curing starts at the same time as the adhesive starts to spread, so that the adhesive The spread of the agent can be reduced, and at the same time, adhesive strength can be obtained.

[0011]

[Embodiment] (Example 1) Hereinafter, an embodiment of the present invention will be described. Parts that are the same as those in FIGS. 1 to 6 and FIGS. 7 to 11 are given the same numbers, detailed explanations will be omitted, and differences will be explained. explain.

FIGS. 1 to 6 show the steps in an embodiment of the present invention, and in the figures, 11 is a hot air generator;
2 is a heater installed inside the IC holding device 8.

[0013] Next, a method of implementing the above configuration will be explained. FIG. 1 shows an IC chip 1 being adsorbed by an IC holding device 8 to apply a conductive adhesive 6 to the protruding contacts 3 of the IC chip 1 on a support 9 on which a conductive adhesive film 7 is formed. 2 shows the process of moving and aligning the protruding contacts 3 of the IC chip 1, as shown in FIG.
When the conductive adhesive film 7 is dipped into the conductive adhesive film 7 and the IC holding device 8 is pulled up, the conductive adhesive 6 is transferred and applied to the protruding contacts 3 of the IC chip 1 as shown in FIG.

Thereafter, as shown in FIG. 4, the protruding contacts 3 of the IC chip 1 coated with the conductive adhesive 6 are aligned so as to match the terminal electrodes 5 on the circuit board 4, and as shown in FIG. The IC holding device 8 is pushed down to connect the terminal electrodes 5 on the circuit board 4 and the protruding contacts 3 of the IC chip 1. At the same time, the IC holding device 8 presses the IC chip 1 against the circuit board 4 while the hot air generator 11 is used to remove the IC. The conductive adhesive 6 is cured by applying hot air to the chip 1. By doing so, a strong adhesive strength can be obtained and the conductive adhesive 6 can be cured while preventing excessive spread, so that the adhesive can be connected by suppressing the spread of the adhesive to 100 μm, which was conventionally 120 μm.

(Embodiment 2) Next, a second embodiment of the present invention will be described.

The conductive adhesive 6 is transferred and applied to the protruding contacts 3 of the IC chip 1, and the protruding contacts 3 of the IC chip 1 and the circuit board 4 are bonded together.
The same steps as in Example 1 are performed until the terminal electrodes 5 are aligned with the terminal electrodes 5, and then the circuit board 4
The upper terminal electrode 5 and the protruding contact 3 of the IC chip 1 are connected, and at the same time, the IC chip 1 is pressed against the circuit board 4 by the IC holding device 8 and heated by the heater 12 built into the IC holding device 8, and the conductive adhesive is heated. 6 is cured. By doing so, as in Example 1, strong adhesive strength can be obtained, and the conductive adhesive 6 can be cured while preventing excessive spreading, and the same effects can be obtained.

According to the above embodiment, the conductive adhesive 6 is cured by the hot air generator 11 or the heater 12 at the same time as the IC chip 1 and the circuit board 4 are connected. This prevents excessive spread and provides a stable connection.

[0018]

Effects of the Invention As is clear from the above embodiments, the conductive adhesive of the present invention has already hardened by the time the IC holding device is separated from the IC chip after the IC chip is mounted on the circuit board. is in a stable state. In addition, the conventional curing process after mounting is no longer necessary.
Since electrical tests can be performed immediately, man-hours can be reduced.

[0019] Since the conductive adhesive is cured while it is being spread over the terminal electrode, even if the amount of transfer coating is larger than usual, the spread of the conductive adhesive on the terminal electrode is 100 μm or less. This has the effect that stable electrical connection can be achieved without causing defects such as short circuits.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional side view of an IC chip and a circuit board showing steps of an IC mounting method in a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional side view of an IC chip and a circuit board showing the steps of the IC mounting method in the first embodiment of the present invention.

[Figure 3]
Partial cross-sectional side view of an IC chip and a circuit board showing steps of an IC mounting method in a first embodiment of the present invention

FIG. 4 shows the steps of the IC mounting method in the first embodiment of the present invention.
Partial cross-sectional side view of C chip and circuit board

FIG. 5 is a partial cross-sectional side view of an IC chip and a circuit board showing the steps of the IC mounting method in the first embodiment of the present invention.

[Fig. 6] Second aspect of the present invention
Partial cross-sectional side view of an IC chip and a circuit board showing the heating process of the IC mounting method in the example of

[Figure 7] Conventional IC
Partial cross-sectional side view of an IC chip and a circuit board showing the steps of the mounting method

[Fig. 8] A partial cross-sectional side view of an IC chip and a circuit board showing the steps of a conventional IC mounting method.

[Fig. 9] A partial cross-sectional side view of an IC chip and a circuit board showing the steps of a conventional IC mounting method.

[Fig. 10] A partial cross-sectional side view of an IC chip and a circuit board showing the steps of a conventional IC mounting method.

[Fig. 11] A partial cross-sectional side view of an IC chip and a circuit board showing the steps of a conventional IC mounting method.

[Explanation of symbols]

1 IC chip 2　Electrode pad 3 Protruding contact 4 Circuit board 5 Terminal electrode 6 Conductive adhesive

Claims (3)

[Claims] 1. An IC mounting method in which protruding contacts formed on electrode pads on an IC chip are connected to terminal electrodes of a circuit board using a conductive adhesive, the IC mounting method comprising: connecting the IC chip to the circuit board; An IC mounting method in which the conductive adhesive is heated while being pressed to cure the conductive adhesive and connect the IC chip to the circuit board. 2. The IC mounting method according to claim 1, wherein the conductive adhesive is heated and cured using hot air. Claim 3: IC as a method for curing conductive adhesive
Claim 1: Heating is performed by a heater built into the holding device.
IC mounting method described.