JPH07131153A - Connecting method for substrate and conductive joining agent - Google Patents

Abstract

PURPOSE:To provide the connecting method of (an electrode of) a semiconductor substrate and (a connecting terminal of) a circuit substrate in a stable state. CONSTITUTION:The first soft conductive particles 7 in large particle diameter is blended with the second hard particles 6 in small particle diameter in an insulating bonding agent 5 to produce a conductive junction agent. This conductive junction agent is selectively provided on a connecting terminal 4 of a circuit substrate 3 by a method such as printing step, etc. Next, the whole surface of semiconductor substrate 1 whereon an electrode 2 is formed on the position corresponding to the connecting terminal 4 of the circuit substrate 3 is coated with an insulating bonding agent 5 to be opposed to the circuit substrate 3 for mutual pressurization. In such a state, the first conductive particles 7 on the circuit substrate 3 are deformed to make the area between electrodes conductive. Finally, the insulating bonding agent 5 is set so that both substrates 1, 3 may be fixedly connected in a specific thickness state by the second particles 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection between (an electrode of) a semiconductor substrate such as an IC chip or an LED chip and (a connection terminal of) a circuit substrate, and relates to a substrate connecting method and a conductive bonding agent. is there.

[0002]

2. Description of the Related Art Conventionally, as a method of connecting a semiconductor substrate and a circuit board, a method of adhering electrodes by using an anisotropic conductive adhesive has been studied as shown in JP-A-60-180132. . The anisotropic conductive adhesive is a mixture of conductive particles dispersed in an insulating adhesive. When connecting to a semiconductor substrate using this anisotropic conductive adhesive, the anisotropic conductive adhesive is mounted not only on the circuit board terminals but also between the connection terminals.

Then, when the connection terminal of the circuit board and the electrode of the semiconductor substrate are heated and pressed with an anisotropic conductive adhesive interposed, the insulation interposed between the connection terminal of the circuit board and the electrode of the semiconductor substrate. The conductive adhesive and the conductive particles flow between the connection terminals, and the connection terminals of the circuit board and the electrodes of the semiconductor substrate are directly connected to the conductive particles. That is, the anisotropic conductive adhesive has conductivity in the thickness direction in the bonded state,
This is an adhesive that has an insulating property in the surface direction and a conductive property.

Therefore, in the connection structure using this anisotropic conductive adhesive, it is possible to easily connect without using alignment when using the anisotropic conductive adhesive, and also to insulate between the connection terminals. Since the conductive adhesive is interposed, the bonding strength can be secured without filling the sealing resin after the bonding.

Further, as disclosed in Japanese Patent Laid-Open No. 3-131089, a photo-curable adhesive other than the electrode portion of the wiring pattern on the glass substrate is selectively cured to form conductive particles on the uncured electrode. It is also known that the glass substrate and the flexible substrate are connected by disposing them.

[0006]

In the connection structure between the semiconductor substrate and the circuit board using the above-mentioned anisotropic conductive adhesive,
It is an absolute requirement that the anisotropic conductive adhesive has conductivity in the thickness direction and has insulation in the plane direction. In order to have conductivity in the thickness direction, at least one conductive particle needs to be interposed between the connection terminal of the circuit board and the electrode of the semiconductor substrate. Further, in order to have an insulating property in the plane direction, it is necessary to maintain a distance at which no conductive particles are electrically connected to the adjacent conductive particles by an insulating adhesive.

However, in the anisotropic conductive adhesive, the intervals of the conductive particles dispersed in the insulative adhesive are not uniform but have a sparse portion and a dense portion. Therefore, it is a condition that one or more conductive particles should be positioned with respect to one connection terminal even in a sparse part and that adjacent conductive particles also have an insulating property in a dense part. By the way, when the electrode pitch to be used is narrow and small, in order to allow one or more conductive particles to ride on the electrode even in the sparse part, it is mixed in the insulating adhesive in order to increase the density of the sparse part. The number of conductive particles will be increased. Then, the density of the conductive particles in the dense portion further increases, and the possibility of short circuit increases.

Further, in the above-mentioned method of connecting (semiconductor) substrates using conductive particles, it is difficult to adhere a fixed number of conductive particles to the electrodes. Therefore, since the number of conductive particles attached to the electrode varies depending on the electrode, even if a constant pressure is applied, the load applied to the conductive particle varies and the crushing method also varies accordingly. Due to this variation, it is difficult to stabilize the connection resistance.

The present invention focuses on the above problems,
The present invention was devised to effectively solve this problem, and the first feature thereof is that the conductive particles are formed only on the required electrode surface, and the amount of deformation of the conductive particles is independent of the number of the conductive particles. Is kept constant so that a stable connection state can always be obtained.

Further, the second characteristic is that a conductive bonding agent (adhesive) mixed with particles is formed only on a necessary electrode surface, and variations are absorbed by deformation of particles in the thickness direction during thermocompression bonding. With this, a stable connection state can always be obtained.

[0011]

In order to solve the above problems, according to the present invention, firstly, as shown in FIG. 1, for example, as shown in FIG. Small and hard second particles 6 are mixed in the insulating adhesive 5 to form a conductive bonding agent, and the conductive bonding agent is selectively printed on the connection terminals 4 of the circuit board 3 by a method such as printing. To form. Next, an insulating adhesive is applied to the entire surface of the semiconductor substrate 1 on which the electrodes 2 are formed at the positions corresponding to the connection terminals of the circuit board, and the insulating adhesive is opposed to the circuit board and pressed against each other. In this state, the first conductive particles 7 on the circuit board are deformed and connected. By the second particles 6, the insulating adhesive is cured and the both substrates are fixedly connected in a state of a constant thickness.

Further, secondly, as shown in FIG. 3, for example, the particles 9 are mixed in the conductive adhesive 7 and semi-cured to form a conductive bonding agent, and the conductive bonding agent is used for printing or the like. And selectively formed on the connection terminals 4 of the circuit board 3 by a method. Next, when the insulating adhesive 5 is applied to the entire surface of the semiconductor substrate 1 on which the electrodes 2 are formed at the positions corresponding to the connection terminals of the circuit board, the insulating adhesive 5 is made to face the circuit board, and pressure is applied to each other. The conductive adhesive 7 is deformed and connected. By the particles 9, the insulating adhesive is hardened and both substrates are fixedly connected in a state of a constant thickness.

[0013]

According to the above-described first substrate connecting method, the first conductive particles 7 are deformed and the second conductive particles 7 are deformed even if the load is varied due to the uneven distribution of the conductive particles on the circuit board. By supporting the first conductive particles 7 with the particles 8, the deformation amount of the first conductive particles 7 is kept constant, and a stable connection state can be obtained.

According to the above-mentioned second substrate connecting method,
Even if the heights of the connection terminals of the circuit board and the electrodes of the semiconductor substrate are varied, the particles 9 are deformed to absorb the variation in the thickness direction and the conductive adhesive 7 conducts the electrodes and the terminals. A stable connection state can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for connecting substrates and a conductive bonding agent according to the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 is a partial sectional view showing the structure of a substrate to which electrodes are connected according to the present invention. As shown in the figure, the circuit board 3 on which the connection terminals 4 are formed
Are electrically connected through the first conductive particles 7 and the second particles 6 in a state corresponding to the electrodes 2 of the semiconductor substrate 1, and these are fixed by the insulating adhesive 5.

The first conductive particles 7 have a large particle size and soft hardness, and have an outer shape of, for example, 3 to 30 μm. The second particles 6 have a small particle size and a high hardness, for example, 1
It has an outer shape of ˜15 μm. The first conductive particles 7 and the second particles 6 are mixed with the insulating adhesive 5. The size of the electrode 2 and the connection terminal 4 is 6
It is about 0 to 100 μm.

The material of the first conductive particles 7 is not particularly limited as long as it is a particle having conductivity at least on the outer peripheral surface, either a simple metal, an alloy of metal, or a resin coating on a resin ball. Preferably, a flexible material is used to stabilize the connection, and for example, nickel balls can be used. The second particles 6 are not particularly limited to conductive or non-conductive, but a material having a hardness of 3 to 10 times that of the conductive particles 7 having a hardness of 1 is preferable, and for example, silica can be used.

As described above, by changing the hardness of the particles, the first conductive particles 7 are crushed and the second particles 6 are not crushed at the time of pressurizing after alignment, and the thickness is maintained so that glass or chips can be obtained. It is possible to absorb the variation in thickness and to connect with a constant thickness.

Further, FIGS. 2A to 2D are sectional views sequentially showing a method of connecting substrates according to the present invention. First, as shown in FIG. 3A, the first conductive particles 7 and the second particles 6 are mixed with the insulating adhesive 5 and the conductive adhesive is applied to the electrodes 4 of the circuit board 3 by a method such as printing. (5) is formed. As the adhesive, a thermosetting adhesive, a photocurable adhesive, or the like can be used. The optimum mixing ratio of the particles and the insulating adhesive is 40 to 70% by weight.

Next, as shown in FIG. 1B, the semiconductor substrate 1 is pressed onto the adhesive layer 5 of the adhesive supply tank 11 to adhere the insulating adhesive 5 to the surface of the semiconductor substrate. .

Further, as shown in FIG. 1C, the semiconductor substrate 1 coated with the insulating adhesive 5 is aligned with the connection terminals 4 corresponding to the electrodes 2 of the semiconductor substrate 1 on the formed circuit board 3. .

Then, as shown in FIG. 3D, pressure is applied after positioning. By this pressurization, the first conductive particles 7 are deformed while absorbing the variations, and the second particles 6 are
It is electrically connected while being kept at a constant thickness. By curing the insulating adhesive 5 in this state, connection and fixing of both substrates are completed.

As described above, according to the present invention, since the electrode of the semiconductor substrate is pressure-connected to the electrode of the corresponding circuit board through the conductive particles, the thickness of the substrate and the number of the conductive particles are limited. Without connection, the first conductive particles 7 are deformed and connected, and the second particles 6 support the pressure and suppress the thickness to a certain thickness, so that a stable connection can be obtained. Further, since the conductive particles are arranged in high density only in the electrode portion, stable electrode connection with a very small pitch is possible. Therefore, based on the above embodiment, the LED chip and L
When the LED array device is manufactured by connecting with the ED driving IC, the first conductive particles 7 and the second particles 6 are interposed in the connecting electrode portion, so that the brightness and the brightness decrease due to the variation in the connection resistance. There is no variation, and a stable connection state can be obtained.

In the above embodiment (method of connecting the boards), the case where the semiconductor substrate is connected to another circuit board has been described, but the invention is not limited to the semiconductor board and the present invention can be applied to other circuit boards. It can be carried out.

In the above-mentioned embodiment (conducting adhesive), the first conductive particles 7 and the second particles 6 are mixed with the insulating adhesive 5 as shown in FIG. However, the base material for mixing may be a simple bonding agent (resin or the like) instead of an adhesive agent.

(Embodiment 2) Next, another embodiment will be described. FIG. 3 is a partial sectional view showing the structure of a semiconductor substrate to which electrodes are connected according to the present invention. As shown in the figure, the circuit board 3 on which the connection terminals 4 are formed is, in a state corresponding to the electrodes 2 of the semiconductor substrate 1, a conductive material including particles 9 having an outer shape of 3 to 30 μm and a conductive adhesive 10. They are electrically connected to each other via a bonding agent for use and fixed by an insulating adhesive 8.

The material of the particles 9 is not particularly limited to conductive or non-conductive material, but the hardness is preferably a flexible material because it absorbs variations in the thickness direction. For example, nickel-plated resin balls are used. ing. And
After applying the conductive adhesive to the connection terminals 4, the conductive adhesive is semi-cured. By doing so, it is possible to break the insulating adhesive layer at the time of pressurizing after alignment and connect to the electrode 2. In addition, the mixed particles 9 absorb variations in the thickness of the electrodes, the connection terminals, etc., and a stable connection is possible.

FIG. 4 is a sectional view sequentially showing a method of connecting substrates according to the present invention. First, as shown in FIG. 1A, a conductive adhesive layer 10 is formed by printing a conductive bonding agent in which particles 9 are mixed with a conductive adhesive 10 on the connection terminals 4 of the circuit board 3. Then half cure.

Next, as shown in FIG. 3B, the semiconductor substrate 1 is pressed onto the insulating adhesive layer 8 of the adhesive supply tank 11 to adhere the insulating adhesive 8 to the surface of the semiconductor substrate. Let As the adhesive, a thermosetting adhesive, a photocurable adhesive, or the like can be used.

Next, as shown in FIG. 1C, the semiconductor substrate 1 coated with the insulating adhesive 8 is replaced with the electrode 2 of the semiconductor substrate 1.
Are aligned on the circuit board 3 on which the connection terminals 4 corresponding to are formed.

After that, pressure is applied as shown in FIG. By this pressurization, the semi-cured conductive adhesive breaks the insulating adhesive layer (8) to establish electrical connection, and the particles 9 are deformed while absorbing the variation in the thickness direction and electrically connected. In this state, the conductive adhesive 10 and the insulating adhesive 8 are cured to complete the connection and fixing of both substrates.

As described above, according to the present invention, since the electrode of the semiconductor substrate is pressure-connected to the electrode of the corresponding circuit substrate through the conductive adhesive containing particles, the circuit board connecting terminal and the semiconductor electrode are connected. With respect to variations in the thickness and the like, the particles are deformed in the thickness direction at the time of connection to absorb and support the variations, so that a stable connection can be obtained. Further, since the conductive adhesive is disposed only on the electrode part, stable electrode connection with a very small pitch is possible. Therefore, also in this embodiment, by interposing the conductive adhesive 10 and the particles 9 in the electrode portion to be connected, there is no decrease in brightness or variation in brightness due to, for example, the dispersion of connection resistance in the LED array device, and a stable connection state is obtained. can get.

In the above embodiment, the case where the semiconductor substrate is connected to another circuit board has been described, but the invention is not limited to the semiconductor substrate and the present invention can be implemented in other circuit boards.

[0035]

As described above, according to the present invention, the first connection is made regardless of the thickness of the substrate and the number of conductive particles.
Since the conductive particles are deformed and become conductive, and the second particles support the pressure to suppress the thickness to a constant value, a stable connection can be obtained.

Further, according to the present invention, the variation in the thickness of the connection terminal and the electrode is supported by absorbing and supporting the variation due to the deformation of the particles in the thickness direction at the time of connection, so that a stable connection can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of a substrate connecting method according to the present invention, and is a partial cross-sectional view showing a configuration of a substrate to which electrodes are connected.

2A to 2D are sectional views sequentially showing a method of connecting the substrates of FIG. 1 according to the present invention.

FIG. 3 is a view for explaining another embodiment of the board connecting method according to the present invention, and is a partial cross-sectional view showing the structure of the board to which electrodes are connected.

4A to 4C are sectional views sequentially showing a method of connecting the substrates of FIG. 3 according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor substrate, 2 semiconductor substrate electrode, 3 circuit board, 4 circuit board connection terminal (electrode), 5 insulating adhesive (bonding agent), 6 2nd particle, 7 conductive 1st particle, 8 insulation Adhesive (bonding agent), 9 particles, 10 conductive adhesive, 11 insulating adhesive supply tank.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display part // G02F 1/1345

Claims (5)

[Claims] 1. A method for connecting a first substrate having an electrode and a second substrate having an electrode, wherein conductive first particles having a large particle size and soft second particles having a small particle size are used. The conductive bonding agent mixed in the bonding agent is interposed between the electrodes of the first and second substrates to be pressure-bonded, and the conductive material interposed between the first and second substrates. The first particles of are squeezed in the thickness direction to conduct electricity between the electrodes,
Also, the second particles keep the substrate spacing constant,
A method of connecting substrates, wherein the first and second substrates are connected to each other. 2. A method for connecting a first substrate having an electrode and a second substrate having an electrode, wherein a conductive bonding agent in which particles having a predetermined particle size are mixed in a conductive bonding agent is used. The first and second substrates are interposed between the electrodes and pressure-bonded, and the electrodes are electrically connected by the conductive bonding agent interposed between the first and second substrates, and the particles are The substrate connecting method is characterized in that the first and second substrates are connected while keeping the substrate spacing constant. 3. The first substrate is a semiconductor substrate having electrodes,
3. The method of connecting a substrate according to claim 1 or 2, wherein the second substrate is a circuit substrate provided with connection terminal electrodes to which electrodes of the semiconductor substrate are respectively connected. 4. The method for connecting substrates according to claim 1 or 2, wherein the bonding agent is an adhesive. 5. A conductive first having a large particle size and a soft hardness.
And a second particle having a small particle diameter and a high hardness are mixed in an insulating bonding agent, and a conductive bonding agent for connecting to a substrate.