JPH09153514A - Semiconductor unit and semiconductor element packaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the internal strain in a bonded part by impregnating in porous spaces of a conductive adhesive agent a liq. sealing resin to fill the gap between a semiconductor element and circuit board and hardening this resin to unify a sealing resin layer with a bonding layer of the adhesive agent. SOLUTION: In a bonding layer 10 of terminal electrodes 2 of a semiconductor element 1 and connecting electrodes 5 of a circuit board 4, porous spaces 13 are filled with a sealing resin, the gap between the element 1 and board 4 is filled with a sealing resin layer 9, and bonded part of the element 1 and board 4 is unified with the filled gap between the element 1 and board 4 whereby the internal strain caused in the bonded part can be reduced by dispersing it in the filled part of the resin, thus ensuring the bond of the element 1 to the board 4, improving the strength and adhesion of the bonded part with the adhesive agent between the element 1 and board 4 as well as the stability of the bond.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor unit in which a semiconductor element is mounted face down on a circuit board and a semiconductor element mounting method suitable for the semiconductor unit.

[0002]

2. Description of the Related Art Conventionally, soldering has been widely used when mounting a semiconductor element on a circuit board. However, in recent years,
Due to the miniaturization of the package of the semiconductor device and the increase in the number of connection terminals, the connection terminal spacing becomes narrower, and it has become increasingly difficult to cope with it by the conventional soldering technique.

Therefore, a method of directly mounting a bare semiconductor element on a circuit board to reduce the mounting area and use it efficiently has been devised. For example, when connecting a semiconductor element to a circuit board, a vapor deposition film of adhesion metal or diffusion prevention metal is formed on the terminal electrode of the semiconductor element in advance, and a solder layer formed by plating is further formed thereon to form the electrode. To do. Next, the semiconductor element is faced down and heated to a high temperature to fuse the solder to the connection electrode of the circuit board. This mounting method is said to be an effective method because the mechanical strength after connection is strong and the connection can be made all at once (for example, Industrial Research Society, published on January 15, 1980, edited by Japan Microelectronics Association). , "IC implementation technology").

Further, as disclosed in US Pat. No. 5,121,190 and Japanese Patent Application Laid-Open No. 6-61303, a mounting method and a semiconductor unit using an encapsulant have been proposed in order to secure the stability of a joint portion by soldering. ing. Hereinafter, with reference to FIG. 5, the conventional method of mounting a semiconductor element and a semiconductor unit mounted by the method will be described. FIG. 5 is a sectional view of an essential part of a conventional semiconductor unit mounted face down.

A conventional semiconductor unit mounted face down as shown in FIG. 5 includes a semiconductor element 1 and a semiconductor element 1.
Of the terminal electrode 2, the circuit board 4, the connection electrode 5 formed on the surface of the circuit board 4, the solder joint portion 15 in which the connection electrode 5 and the terminal electrode 2 are joined, and the sealing in which the semiconductor element 1 is sealed. It is composed of resin 16 and the like.

Next, a method of mounting a semiconductor element for forming the conventional semiconductor unit will be described. First, the semiconductor element 1 having solder bumps is mounted face down on the circuit board 4, and the solder bumps are aligned with predetermined positions of the connection terminals 5. Next, the solder is melted by heating to a high temperature of 200 to 300 ° C., the solder bumps and the connection terminals 5 are joined, and the semiconductor element 1 is connected to the circuit board 4 by the solder joints 15.
Fixed to After that, the liquid sealing resin 16 is filled in the gap between the semiconductor element 1 and the circuit board 4 and is heated and cured at about 120 ° C. to solidify the sealing resin 16. In this way, the mounting of the semiconductor 1 on the circuit board 4 is completed.

[0007]

However, the conventional semiconductor unit and semiconductor element mounting method described above has the following problems. First, the solder joint 15
Has high rigidity and lacks flexibility. Therefore, when the liquid sealing resin 16 filled in the gap between the semiconductor element 1 and the circuit board 4 is thermally cured, the semiconductor element 1 and the circuit board 4 are cured.
The thermal stress caused by the difference in the coefficient of thermal expansion of the solder joint 15
And a large internal distortion occurs. Secondly, when the semiconductor unit is used, thermal stress caused by the difference in thermal expansion coefficient between the semiconductor element 1 and the circuit board 4 is applied to the solder joint portion 15, and particularly when the semiconductor element 1 is used in a high temperature region. New thermal stress caused by the thermal expansion of the sealing resin 16 in the gap between the circuit board 4 and the circuit board 4 is applied to the solder joint portion 15. As a result, the reliability of the connection between the semiconductor element 1 and the circuit board 4 was low, and it was not so practical.

The present invention has been made to solve the above-mentioned problems of the conventional example, and provides a semiconductor unit and a mounting method of the semiconductor element in which the reliability of the connection between the semiconductor element and the circuit board is improved. It is an object.

[0009]

In order to achieve the above object, a semiconductor unit of the present invention comprises a semiconductor element mounted face down on a circuit board, wherein the terminal electrodes of the semiconductor element and the circuit board are mounted. A connection layer for electrically and mechanically connecting the connection electrode of, and a sealing resin layer filled in a gap between the semiconductor element and the circuit board, wherein the bonding layer is a porous conductive adhesive and The porous space of the electrically conductive adhesive is impregnated with the sealing resin and cured to be integrated.

In the above structure, it is preferable that a protruding electrode is provided on the terminal electrode of the semiconductor element. Further, in each of the above configurations, it is preferable that the bonding layer and the sealing resin layer have the same coefficient of thermal expansion.

Further, in each of the above constitutions, it is preferable that the sealing resin layer contains an inorganic filler larger than the porous space of the porous conductive adhesive.

On the other hand, the semiconductor element mounting method of the present invention is
A step of mounting a semiconductor element on a circuit board in a face-down state, the step of connecting the terminal electrode of the semiconductor element to a connection electrode of the circuit board in a face-down state by a porous conductive adhesive; A step of filling a liquid sealing resin in a gap between the liquid sealing resin and the circuit board; a step of impregnating the liquid sealing resin into a space of the porous conductive adhesive; and a step of curing the liquid sealing resin. Including steps.

In the above structure, it is preferable to include a step of providing a protruding electrode on the terminal electrode of the semiconductor element.
In each of the above configurations, it is preferable that the porous conductive adhesive be obtained by curing a solvent-type conductive adhesive containing at least a solvent, an organic resin, and a conductive filler.

Further, in each of the above constitutions, it is preferable that the liquid sealing resin has no solubility in the conductive adhesive after curing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A semiconductor unit and a semiconductor element mounting method suitable for the same according to the present invention include a semiconductor element and a circuit board, which are mounted face down on a circuit board using a porous conductive adhesive. The porous space of the conductive adhesive is impregnated with the liquid sealing resin that fills the gaps, and the liquid sealing resin is cured. Thereby,
The joint portion between the semiconductor element and the circuit board and the filling portion in the gap between the semiconductor element and the circuit board are integrated. As a result, it is possible to reduce the internal strain by dispersing the internal strain generated in the bonding portion to the filling portion of the sealing resin, and to ensure the bonding between the semiconductor element and the circuit board. Also,
Since the conductive adhesive at the joint portion fills the porous space with the sealing resin, the strength and adhesion of the joint portion due to the conductive adhesive between the semiconductor element and the circuit board are increased to improve the stability of the joint. Can be improved.

(First Embodiment) A first embodiment of a semiconductor unit and semiconductor element mounting method according to the present invention will be described below with reference to FIGS. 1 to 3. In FIG. 1, (a) to (d) are process drawings for explaining a mounting method of a semiconductor element in the first embodiment, and (d) is a sectional view showing a configuration of a semiconductor unit in the first embodiment. Is. Further, FIG. 2 is a cross-sectional view of a main part for explaining a bonding layer of a porous conductive adhesive, and FIG. 3 is a cross-sectional view of a main part for explaining a bonding layer of a conductive adhesive integrated with a sealing resin. .

As shown in FIG. 1D, the semiconductor unit according to the first embodiment has a semiconductor element 1, a terminal electrode 2 formed on the semiconductor 1, a circuit board 4, and a surface of the circuit board 4. The connection electrode 5 formed on the substrate, the bonding layer 10 for electrically and mechanically connecting the terminal electrode 2 and the connection electrode 5, and the sealing resin layer 9 filled in the gap between the semiconductor element 1 and the circuit board 4. Etc. In addition, in FIG. 1 (a)-(c),
3 is a solvent-type conductive adhesive used for mounting the semiconductor element 1, 6 is a bonding layer of a porous conductive adhesive, 7 is a liquid sealing resin, and 8 is a liquid sealing resin 7 impregnated. It is a bonding layer of a conductive adhesive.

Next, a method of mounting the semiconductor element according to the first embodiment will be described. The solvent-type conductive adhesive 3 is applied to the terminal electrodes 2 of the semiconductor element 1 in advance.
The solvent-type conductive adhesive 3 has at least a solvent (for example, B
CA), an organic resin (for example, a phenoxy resin), and a conductive filler (for example, Ag powder). And
As shown in FIG. 1A, the semiconductor element 1 is placed face down (downward) on the connection electrodes 5 of the circuit board 4, and the semiconductor element 1 is mounted on the circuit board 4. Thereafter, as shown in FIG. 1B, the solvent-type conductive adhesive 3 is cured, and the terminal electrode 2 of the semiconductor element 1 and the connection electrode 5 of the circuit board 4 are bonded to each other by a porous conductive adhesive bonding layer 6 Electrically connected by. At this time, by curing the solvent-type conductive adhesive 3, the contained solvent evaporates, and as shown in FIG. 2, the conductive filler 11 and the organic resin 1
2 remains to form a porous conductive adhesive bonding layer 6 having a porous space 13.

Next, as shown in FIG. 1C, a liquid sealing resin 7 (for example, a bisphenol F type liquid resin, a curing agent of a phenol compound, and a silica filler) is filled in the gap between the semiconductor element 1 and the circuit board 4. The composition containing) is filled. At this time, the liquid sealing resin 7 is impregnated into the porous space 13 of the porous conductive adhesive bonding layer 6, and the conductive adhesive bonding layer 8 impregnated with the liquid sealing resin is obtained. At this time, in order to maintain the electrical connection by the conductive adhesive, a liquid sealing resin 7 that is not soluble in the conductive adhesive is used.

Then, the liquid encapsulating resin 7 is cured to form a cured encapsulating resin filling layer 9 in the gap between the semiconductor element 1 and the circuit board 4 as shown in FIG. 1D. At the same time, the bonding layer 10 of the conductive adhesive integrated with the sealing resin is obtained. At this time, in the conductive adhesive bonding layer 10 integrated with the sealing resin, as shown in FIG. 3, the porous space 13 of the porous conductive adhesive is impregnated with the sealing resin. Therefore, a semiconductor unit integrated with the filling layer 9 of the sealing resin can be obtained.

In the process of hardening the liquid sealing resin 7,
Porous space 1 of the bonding layer 6 of porous conductive adhesive
The liquid sealing resin impregnated in 3 and the liquid sealing resin 7 in the gap between the semiconductor element 1 and the circuit board 4 simultaneously undergo a curing reaction. At this time, the internal strain can be reduced by dispersing the internal strain generated in the bonding step during the curing process due to the difference in the thermal expansion coefficient between the semiconductor element 1 and the circuit board 4.
The bonding between the semiconductor element 1 and the circuit board 4 can be ensured.

In the semiconductor unit formed as described above, in the bonding layer 10 between the semiconductor element 1 terminal electrode 2 and the connection electrode 5 of the circuit board 4, the porous space is filled with the sealing resin, and A sealing resin layer 9 is filled in the gap between the semiconductor element 1 and the circuit board 4.
Therefore, the strength and adhesion of the joint between the semiconductor element 1 and the circuit board 4 by the conductive adhesive are increased, and a semiconductor unit with a highly reliable connection between the semiconductor element 1 and the circuit board 4 can be obtained. At this time, in the sealing resin, the bonding layer 10 of the conductive adhesive integrated with the sealing resin, the sealing resin layer 9 in the gap between the semiconductor element 1 and the circuit board 4 have the same thermal expansion coefficient. It is desirable to adjust the compounding amount of the silica filler.

(Second Embodiment) Next, a first embodiment of a method of mounting a semiconductor unit and a semiconductor element according to the present invention will be described with reference to FIG. FIG. 4 is a main-portion cross-sectional view showing the structure of the semiconductor unit according to the second embodiment. Compared to the case of the first embodiment, the difference is that the protruding electrode 14 is formed on the terminal electrode 2 of the semiconductor element 1.
The other configuration is substantially the same as that of the first embodiment, and thus the description is omitted.

Au or the like is used as the material of the bump electrodes 14. By forming the protruding electrode 14 on the terminal electrode 2,
In addition to the effects of the first embodiment, the spread of the conductive adhesive 3 when the semiconductor element 1 is mounted on the circuit board 4 can be restricted, and the bonding can be performed at a fine pitch. Further, the gap between the semiconductor element 1 and the circuit board 4 can be widened by the height of the bump electrode 14, and the thermal stress can be further alleviated.

In each of the above embodiments, the conductive adhesive 3 is applied to the semiconductor element 1 side.
The same effect can be obtained by applying the conductive adhesive 3 to the connection electrode 5 side of the circuit board 4. Further, the conductive adhesive 3 is not limited to the solvent-type conductive adhesive, and may be any one as long as it has a porous space and has electrical continuity after curing. Furthermore, if the size of the inorganic filler such as silica to be mixed in the sealing resin layer 9 to adjust the thermal expansion coefficient is larger than the porous space 13 of the porous conductive adhesive, the effect is further enhanced. Can be demonstrated.

[0026]

As described above, the semiconductor unit of the present invention is one in which a semiconductor element is mounted face down on a circuit board, and the terminal electrodes of the semiconductor element and the connection electrodes of the circuit board are electrically connected. It has a connection layer for mechanical and mechanical connection and a sealing resin layer filled in the gap between the semiconductor element and the circuit board, and the bonding layer is sealed in a porous space between the conductive adhesive and the conductive adhesive. Since they are integrated by being impregnated with the stop resin and then cured, the joint portion between the semiconductor element and the circuit board and the filling portion in the gap between the semiconductor element and the circuit board are integrated. As a result, it is possible to reduce the internal strain by dispersing the internal strain generated in the bonding portion to the filling portion of the sealing resin, and to ensure the bonding between the semiconductor element and the circuit board. In addition, since the conductive adhesive at the joint is filled with the porous space by the sealing resin, the strength and adhesion of the joint due to the conductive adhesive between the semiconductor element and the circuit board are increased to stabilize the joint. It is possible to improve the sex.

Further, by providing the protruding electrodes on the terminal electrodes of the semiconductor element, it is possible to restrict the spread of the conductive adhesive when the semiconductor element is mounted on the circuit board, and it is possible to join at a fine pitch. Become. Further, the gap between the semiconductor element and the circuit board can be widened by the height of the protruding electrode, and the thermal stress can be further alleviated. Further, by making the thermal expansion coefficient of the bonding layer and the sealing resin layer the same,
It is possible to prevent peeling or cracking at the interface between the bonding layer and the sealing resin layer. Further, by including an inorganic filler larger than the porous space of the porous conductive adhesive in the sealing resin layer, it becomes easy to adjust the thermal expansion coefficient of the bonding layer and the sealing resin layer.

On the other hand, the semiconductor element mounting method of the present invention is
A semiconductor element is mounted face down on a circuit board, the step of connecting the terminal electrodes of the semiconductor element to the connection electrodes of the circuit board in a face down state with a porous conductive adhesive, and the semiconductor element and the circuit board. Since it includes a step of filling a liquid sealing resin in a gap between the liquid sealing resin, a step of impregnating the liquid sealing resin into the space of the porous conductive adhesive, and a step of curing the liquid sealing resin, It is possible to easily manufacture a semiconductor unit having.

As a porous conductive adhesive, a solvent-type conductive adhesive containing at least a solvent, an organic resin, and a conductive filler is cured to easily form a porous space by volatilizing the solvent. be able to.
Further, by using a liquid encapsulating resin that is not soluble in the conductive adhesive after curing, it is possible to prevent damage to the bonding layer once formed by the injection of the encapsulating resin. .

[Brief description of the drawings]

1A to 1D are process diagrams showing a first embodiment of a semiconductor element mounting method of the present invention, and further, FIG.
Also serves as a main-portion cross-sectional view showing the configuration of the first embodiment of the semiconductor unit of the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining a bonding layer of a porous conductive adhesive according to the first embodiment.

FIG. 3 is a cross-sectional view of essential parts for explaining a bonding layer of a conductive adhesive integrated with a sealing resin according to the first embodiment.

FIG. 4 is a main-portion cross-sectional view showing the configuration of the second embodiment of the semiconductor unit of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing the configuration of a conventional semiconductor unit mounted face down.

[Explanation of symbols]

 1: Semiconductor element 2: Terminal electrode 3: Solvent-type conductive adhesive 4: Circuit board 5: Connection electrode 6: Porous conductive adhesive bonding layer 7: Liquid sealing resin 8: Liquid sealing resin Bonding layer of conductive adhesive impregnated with 9: Sealing resin layer after curing 10: Bonding layer of conductive adhesive integrated with sealing resin 11: Conductive filler 12: Organic resin 13: Porous space 14: Projection electrode 15: Solder joint 16: Sealing resin

Claims (8)

[Claims] 1. A semiconductor unit in which a semiconductor element is mounted on a circuit board in a face-down state, the connection layer electrically and mechanically connecting a terminal electrode of the semiconductor element and a connection electrode of the circuit board, A sealing resin layer filled in a gap between the semiconductor element and the circuit board, the bonding layer impregnating the sealing resin into a porous conductive adhesive and a porous space of the conductive adhesive, and curing A semiconductor unit that is integrated as a result. 2. The semiconductor unit according to claim 1, wherein a protruding electrode is provided on the terminal electrode of the semiconductor element. 3. The semiconductor unit according to claim 1, wherein the bonding layer and the sealing resin layer have the same thermal expansion coefficient. 4. The semiconductor unit according to claim 1, wherein the sealing resin layer contains an inorganic filler larger than a porous space of the porous conductive adhesive. 5. A semiconductor element mounting method for mounting a semiconductor element on a circuit board in a face-down state, wherein a terminal electrode of the semiconductor element is face-down to a connection electrode of the circuit board with a porous conductive adhesive. A step of connecting with, a step of filling a liquid sealing resin in the gap between the semiconductor element and the circuit board, a step of impregnating the liquid sealing resin into the space of the porous conductive adhesive,
A method for mounting a semiconductor element, comprising the step of curing the liquid sealing resin. 6. The method of mounting a semiconductor element according to claim 5, including a step of providing a projection electrode on a terminal electrode of the semiconductor element. 7. The semiconductor according to claim 5, wherein the porous conductive adhesive is obtained by curing a solvent-type conductive adhesive containing at least a solvent, an organic resin and a conductive filler. Device mounting method. 8. The method for mounting a semiconductor element according to claim 5, wherein the liquid encapsulating resin has no solubility in a cured conductive adhesive.