JPH0613432A - Connecting method for semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To provide an electrical connecting method, which reduces a deterioration rate with age in connection resistance between a circuit board and a semiconductor integrated circuit chip, and provides a stable characteristic against stress caused by a difference between coefficients of thermal expansion. CONSTITUTION:An elastic conductive particle or a conductive particle and an elastic non-conductive particle kneaded with an insulating adhesive are used to form a conductive connector 112. A connecting electrode 110 in a semiconductor integrated-circuit chip 102 and a circuit-board electrode 114 in a circuit board 116 are connected electrically through the conductive connector 112.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method of connecting a semiconductor integrated circuit device and a circuit board, after sealing the semiconductor integrated circuit device, the sealed semiconductor integrated circuit device is connected to the circuit board through a socket. In general, this method is used, or this socket is omitted and the sealed semiconductor integrated circuit device is directly soldered to the circuit board.

In the method of connecting by using a socket, the sliding portion of the connection portion of the socket or the mechanical deformation of the elongated foot pin portion of the semiconductor integrated circuit device component that has been sealed causes mechanical deformation.
Mechanical strain and stress due to the difference in thermal expansion coefficient between the circuit board and the semiconductor integrated circuit device are absorbed, and both mechanical connection and electrical connection are achieved.

Furthermore, the surface of the electrical contact portion of the socket is plated with gold to prevent a connection failure due to oxidation.

These mounting methods are excellent methods that have been used for many years. However, the volume required for mounting the semiconductor integrated circuit device and the circuit board is large, which is a bottleneck for downsizing the device.

As a method for solving the problem that the mounting volume is large, solder bump electrodes called bumps are formed on each connection electrode portion of a semiconductor integrated circuit piece (hereinafter referred to as an IC chip), and the solder bump electrodes are directly formed on the circuit board. A so-called flip chip method of soldering an IC chip has been proposed and put into practical use.

However, the IC chip and the circuit board are tens of μ
Since they are opposed to each other at a short distance of m and are mechanically fixed by using solder bumps having a large diameter of several tens of μm, deformation occurs due to the difference in the thermal expansion coefficient between the mechanical dimensions of the IC chip and the circuit board, which causes stress. There is no escape, which causes mechanical destruction.

In order to suppress this mechanical destruction, when a silicon IC chip and a circuit board made of an epoxy material are connected, the size of the IC chip is several mm, and the silicon IC chip and the glass material are used. When connecting to a circuit board, the maximum size of the IC chip is about 10 mm.

Instead of solder bumps, gold bumps are formed on an aluminum electrode, which is an external connection electrode of a semiconductor integrated circuit device, via a barrier metal layer, and a thin copper foil is formed on a thin insulating film to form a flexible pattern. A so-called TAB method has been proposed in which an IC chip is mounted on a flexible circuit board to absorb deformation and stress due to a difference in thermal expansion coefficient and to connect this flexible circuit board to a normal circuit board. It has been implemented.

However, in this TAB method, a mounting area for interposing a flexible circuit board becomes large, and a step for forming a barrier metal layer is added to a semiconductor integrated circuit device, and a gold bump is formed. There is a drawback of increased cost due to the use of precious metals.

Furthermore, the use of the noble metal in the connection portion between the IC chip and the flexible circuit board having the fine pattern is such that noble metal is eluted and recrystallized between the connection electrodes at a short distance in the simple moisture-proof resin sealing. There is a drawback in reliability in that an electrode short circuit accident due to is likely to occur.

Although there is some concern about reliability as one of inexpensive mounting methods, there is a method of directly mounting an IC chip on a circuit board using a conductive paste.

In order to electrically connect only the connection electrode portion of the IC chip to the circuit board, an aluminum electrode, which is an external connection electrode of the semiconductor integrated circuit device, is plated with gold called a bump. A large number of projecting electrodes of μm are formed. Further, by using a letterpress printing method known from old days, a conductive paste is applied only to the protruding electrode portion and connected to the circuit board.

The conductive paste for connecting the IC chip and the circuit board is a mixture of a two-liquid type or thermosetting adhesive and silver particles or palladium silver fine particles, and is mechanically and electrically connected. And at the same time.

In order to establish a connection using this conductive paste, the heights of a large number of protruding electrodes are made uniform, and the pitch dimension between the connecting electrodes is made sufficiently wide to allow the conductive paste to protrude from the connecting electrodes. It must be greater than the distance.

Further, also in the mounting method using this conductive paste, it is necessary to solve the problems of stress and deformation due to mechanical strain generated due to the difference in thermal expansion coefficient.

At present, the size of the IC chip in the mounting method using the conductive paste is practically a few mm or less. With an IC chip of a size larger than this, peeling of the connection or breakage of the IC chip occurs due to mechanical strain.

Further, in the mounting method using the conductive paste, the cost is increased due to an additional step in the manufacturing process of the semiconductor integrated circuit for forming the bumps described above, and the IC chip for a large connecting electrode which is different from usual is formed. There is a decrease in area efficiency, and the unit price of the IC chip is increased.

That is, in the comprehensive evaluation of reliability, cost and mounting volume, the economic effect of directly mounting the IC chip on the circuit board is not necessarily large, and there is an unstable factor in reliability, and only the volume effect is present. Tends to depend on the superiority of.

However, downsizing of the device is a trend of the times,
IC chip mounting area, mounting volume reduction, and epoch-making reduction in connection cost of multiple connection terminals are strongly desired, and the emergence of effective technology is awaited.

For convenience of understanding the above, the sectional view of FIG. 7 shows a sectional structure including an IC chip and a circuit board in a conventional mounting method using a conductive paste.

As shown in FIG. 7, the IC chip 702 is
The protective film layer 708 is formed so that a part of the metal conductive layer 706 made of aluminum at the uppermost part of the active region 704 forming elements such as transistors and resistors and capacitors is exposed.
The connection hole is formed by etching. This metal conductive layer 70
Bumps 710 are provided on 6 via a barrier layer (not shown) made of a single layer film of chromium or titanium or a laminated film.

The bump 710 is made of copper, and a gold plating film is provided on the copper surface. The diameter of the bump 710 is hundreds of tens of μm.
The bump height is several tens of μm. Usually bump 71
The 0 height variation is about 10 μm.

The conductive paste 712 is the IC chip 702.
Since the gap between the circuit board 716 and the circuit board 716 is defined, the height error of the bump 710 is absorbed, and the conductive paste 7
The lateral protrusion amount of 12 has a degree of variation in the height of the bump 710, that is, a variation of about 10 μm.

For this reason, the bump-to-bump distance 748 requires a distance of at least twice the minimum protrusion amount of the conductive paste 712, for example, a dimension of 30 μm or more, so that adjacent electrodes do not short-circuit under the worst conditions.

Therefore, in reality, it is not possible to mount the electrode pitch of the IC chip 702 to be several tens of μm or less.

Further, the variation in height of the bumps 710 causes a short circuit accident to reduce the connection yield, and further, the temperature change causes a disconnection in the mounting area, which makes the connection resistance unstable.

Apart from the connection method using the conductive paste,
A structure has been proposed in which the height of the gold bump is lowered to several μm and the gold bump is directly pressed against the circuit board, and the IC chip and the circuit board are connected by an ultraviolet curable resin. However, it is impossible to absorb the bump height variation only by pressing pressure.

As another method for connecting the IC chip and the circuit board, a plastic ball coated with a conductive film is used.
Cover with a thinner film of heat-melting plastic,
There is also a proposal of a structure in which a gold bump having a height of m is adhered to a circuit board, and the circuit board and the IC chip are electrically connected by heat to escape a short circuit between electrodes in the lateral direction. Materials and conditions that allow for short circuit prevention are strict.

[0030]

As described above,
Problems to be solved by the conventional IC chip mounting method include reduction in cost of forming a protruding electrode for connection called a bump formed on the IC chip, reduction in electrode area, and metal elution recrystallization short circuit accident. The use of expensive noble metals that may cause this is eliminated, the connection is prevented from peeling off due to the difference in thermal expansion coefficient, and the IC chip is prevented from being destroyed.

An object of the present invention is to provide a new connection method for solving the above problems. More specifically, it is an object of the present invention to provide a connection method that is stable without using a precious metal, has excellent conductivity, and is unlikely to cause a metal-eluting recrystallization short circuit.

[0032]

In order to achieve the above object, the present invention employs the method described below.

In the method for connecting a semiconductor integrated circuit device according to the present invention, a semiconductor integrated circuit piece having a connection electrode and a circuit board having a circuit board electrode are made of elastic conductive particles, or elastic with conductive particles. A non-conductive particle having a certain amount is kneaded together with an insulating adhesive to form a conductive connecting body, and a circuit board electrode and a semiconductor integrated circuit piece are bonded at a particle diameter interval of the conductive particle or the non-conductive particle to form a semiconductor integrated circuit piece. The connecting electrode and the circuit board electrode of the circuit board are electrically connected using a conductive connector.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows one embodiment of a method for connecting a semiconductor integrated circuit device according to the present invention.

As shown in FIG. 1, the IC chip 102 is
An opening is formed in the protective film 108 so that the connection electrode 110 made of aluminum is exposed on the active region 104 in which active elements such as transistors, resistors and capacitors and passive elements are formed.

On the other hand, a circuit board electrode 114 is provided on the circuit board 116. In the case of a liquid crystal display device, the circuit board 116 is a glass substrate, and the circuit board electrode 114 is composed of a transparent electrode film.

The connection electrode 110 of the IC chip 102 and the circuit board electrode 114 are electrically connected by using the conductive connector 112.

Next, a description will be given of an embodiment in which the circuit board electrode of the circuit board and the connection electrode of the IC chip are connected using the conductive connector.

As shown in FIG. 2, the conductive connector has a conductive coating 212 of palladium silver or an oxide conductor formed on the surface of elastic insulating plastic particles 210 such as Tetron or polyimide. Further, it is configured by providing insulating particles 214 made of insulating plastic particles having a low softening point or wax particles. The size of the insulating particles 214 is 1 μm or less.

The IC chip 202 and the circuit board 206 are
The spacer members 230 in the adhesive 232 arranged on both sides of the IC chip 202 oppose each other at a constant interval, for example, 5 μm. At the same time, the insulating plastic particles 210 having conductivity are distorted to generate a connection pressure.

The surface of the insulating plastic particles 210 is
Although being electrically conductively coated with the electrically conductive coating 212, the insulating plastic particles 210 are strongly pressured in the vertical direction in FIG.
The insulating particles 214 on the surface of the substrate are buried in the insulating plastic particles 210 or are crushed by heat, so that the circuit board electrode 208 and the connection electrode 2 of the IC chip 202 are vertically arranged.
04 and conductive.

However, in the lateral direction of the electrodes, since there is a relief area for pressure, the insulating particles 214 are not buried or crushed, and conduction is not performed.

The particles that give continuity are uniformly applied to the IC chip 202 or the circuit board 206 with a planar density such that they do not adhere to each other.

However, the insulating plastic particles 2
Due to the presence of the insulating particles 214 on the surface 10, the electric conduction in the lateral direction of the electrode is alienated, and a strong pressure can be generated only in the vertical direction of the electrode so that the electric conduction occurs.

Since only the regions where the conductive connection electrodes 204 and the circuit board electrodes 208 are present on the top and bottom are conductive, unlike the conventional method of pattern printing by the relief printing method, a pattern of about 10 .mu.m pitch is used. Up to fine pitch electrode connection can be achieved.

FIG. 3 shows still another embodiment of the method for connecting a semiconductor integrated circuit device of the present invention.

As shown in FIG. 3, the conductive connecting member is a conductive particle 312 in which palladium silver or an oxide conductive film is formed on the surface of a flexible insulating plastic such as tetron or polyimide having a diameter of about several μm. And conductive particles 3
A non-conductive particle 310 made of an insulating plastic such as Tetoron or a polyimide having a particle size smaller than 12 is kneaded with an insulating adhesive 314 to be formed.

Two kinds of particles, that is, the conductive particles 312 and the non-conductive particles 310, are mixed and are in the vertical direction, that is, the IC.
Conductive particles 312 and non-conductive particles 310 are arranged in a layer between the connection electrode 304 of the chip 302 and the circuit board electrode 308 of the circuit board 306, and the conductive particles 312 and the non-conductive particles 312 are non-conductive in the lateral direction. The particles 310 are mixed and arranged.

Regarding the direction of the one-layer arrangement, by setting the size of the spacer member 330 mixed in the adhesive 332 to be smaller than the size of the conductive particles 312, a pressing pressure is generated on the conductive particles 312 and the connection electrode 304. And circuit board electrode 30
Conduction with 8 is obtained.

Since the conductive particles 312 and the non-conductive particles 310 are connected in series in the lateral direction of the electrode, the ratio of the conductive particles 312 to the non-conductive particles 310 is 1/7.
If it is set below, it becomes possible to make all the periphery of one conductive particle 312 the non-conductive particle 310, and the short circuit in the lateral direction of the electrode does not occur.

The diameter of the non-conductive particles 310 is set to be that of the conductive particles 3.
By making it slightly smaller than the diameter of 12, it is possible to prevent the conduction probability in the vertical direction of the electrode from decreasing, and prevent the conduction probability from decreasing.

However, if the diameter of the non-conductive particles 310 is set to 1/4 or less of the diameter of the conductive particles 312, the dimensional effect of preventing the non-conductive particles 310 from connecting in the lateral direction is reduced.

FIG. 4 shows still another embodiment of the present invention, showing a connecting method using an anisotropic conductive member.

The sheet-shaped anisotropic conductive member is obtained by bending a thin wire of a shape memory alloy slightly by cold working and fixing it in a soft medium such as insulating plastic. The shape memory alloy fine wire is preferably plated with silver or palladium in order to enable orientation in a magnetic field by a plating treatment with iron or nickel and further reduce the connection resistance. There is also an advantage that it is easy to make a method in which the shape memory alloy fine wires are previously coated with an insulating coating and then bundled and fixed with an insulating adhesive.

As shown in FIG. 4, a shape memory alloy fine wire 404 is covered with an insulating adhesive 402 by a sheath 406 made of soft plastic to form a sheet, which is used as an anisotropic conductive member.

The shape memory alloy exhibits plasticity below a certain temperature, but loses plasticity when the temperature rises above a certain temperature and returns to the shape at high temperature.

Therefore, the shape memory alloy thin wire 4 obtained by bending the shape memory alloy thin wire 404 which is straight at high temperature by cold working.
04 by using an insulating adhesive 4 between the IC chip and the circuit board.
When the IC chip is mounted, the shape-memory alloy thin wire 404 is stretched straight when it is heated after being fixed by using 02.
The contact pressure for connection, which has been reduced due to buckling or deformation, is restored and the mounting connection resistance can be stably secured.

The sheath 406 is effective in preventing short circuit due to electrical contact between the shape memory alloy thin wires 404 and forming an insulating sheet of the anisotropic conductive member. Further sheath 40
When 6 is made of a heat softening material such as wax, the connection pressure is easily generated due to the shape recovery of the shape memory alloy fine wire 404 during heating.

The insulating adhesive 402 is used not only for fixing the shape memory alloy fine wire 404 into a sheet shape, but also for fixing the IC chip and the circuit board.

FIG. 5 shows an example of the structure of the conductive particles of the present invention.

FIG. 5A shows a shape memory alloy thin wire 502 which is cooled and rounded into small pieces, and FIG. 5B shows a shape memory alloy thin wire and a plastic material or a wax material which are rounded into spherical conductive particles 504. Fig. 5
(C) is a shape-memory alloy thin wire ball 5 expanded by heating.
06 are shown respectively.

The rounded shape memory alloy fine wires 502 tend to be entangled with each other by themselves, and it is difficult to form an anisotropic conductive structure such as plastic particles whose surfaces are conductively coated.

However, the spherical conductive particles 504 obtained by kneading the shape memory alloy fine wire 502 together with a wax material or a plastic material can be made into a dumpling shape and can be handled as conductive particles while preventing entanglement.

Further, in the spherical conductive particles 504, the shape memory alloy fine wire swells in the molten wax sphere after the heating process after mounting, and the shape memory alloy fine wire ball 506 shown in FIG. The conductive particles made of a plastic material have an advantage over the conductive particles made of a plastic material.

Alternatively, a flexible thin wire, or a flexible insulating thin wire coated with a metal oxide film or a metal film to have conductivity and kneaded with wax at a low temperature is a shape memory alloy. In the same manner as above, since it expands in a basket shape in the high temperature heating step to generate a connection pressure, it can be used similarly to the conductive particles shown in FIG.

FIG. 6 shows an embodiment of a chip-on-glass mounting method in which the semiconductor integrated circuit device connection method of the present invention is applied to the connection between the wiring on the glass substrate forming the liquid crystal display element and the IC chip.

As shown in the sectional view of FIG. 6, a liquid crystal layer 600 is provided between a glass substrate 604 and a glass substrate 606 which form a liquid crystal display device. This liquid crystal layer 600 is a sealing material 6.
It is enclosed by the glass substrate 604 between the glass substrate 604 and the glass substrate 606.

Deflection plates 624 and 626 are provided on the glass substrates 604 and 606, respectively, for defining the directions of the vibration planes of light.
To provide.

Further, the respective glass substrates 604, 60
6 is provided with transparent electrode films 630 and 632 for displaying.

Further, a liquid crystal driving IC chip 602 for driving the liquid crystal display device is mounted on the glass substrate 604 by a conductive connector 608 using the connection method of the present invention.

A signal and a power source for controlling the liquid crystal driving IC chip 602 are supplied from a circuit board connecting electrode 614 which is connected to the glass substrate 604 by using a thermosetting conductive adhesive 612.

As shown in FIG. 6, the transmitted light 628 is modulated as it passes through the liquid crystal layer 600, and the deflection plates 624 and 626 are modulated.
Is changed to amplitude modulation.

Glass substrate 604 which constitutes a liquid crystal display element
Transparent conductive films 630 and 632 made of indium tin oxide mixture thin films are formed on the surfaces of the glass substrate 606 and a driving voltage is applied to the liquid crystal layer 600.

The transparent conductive films 630 and 632 are arranged so as to face each other with a narrow gap of several μm, and the liquid crystal layer 600 oriented in a certain direction is sandwiched therebetween.

The mechanical strain due to the difference in thermal expansion coefficient between the glass substrate 604 and the liquid crystal driving IC chip 602 due to the temperature change is absorbed by the use of the conductive connector 608,
The connection pressure for electrical connection is stably maintained by the connection method of the present invention, and the problem of electrical connection does not occur.

[0076]

As is apparent from the above description, in the method of connecting a semiconductor integrated circuit device of the present invention, since the IC chip and the circuit board are connected without using a precious metal, the characteristic of the precious metal is provided. The metal elution short circuit accident can be suppressed. Further, unlike the conductive paste used conventionally, the conductive connector used in the connecting method of the present invention is physically and chemically stable.

Therefore, the electrode pitch is about 10 μm, which makes it possible to mount the IC chip with a smaller dimension than the conventional one. Further, since a time-consuming and troublesome process such as a letterpress printing process for forming the conductive paste is not required, the process cost can be significantly reduced. From the viewpoint of connection stability, the shape memory alloy effect ensures a stable connection pressure against temperature thermal expansion and aging, and is excellent in connection stability and reliability. Further, since no precious metal is used, the material cost is excellent.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of connecting a semiconductor integrated circuit device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a method of connecting a semiconductor integrated circuit device according to an embodiment of the invention.

FIG. 3 is a sectional view showing a method of connecting a semiconductor integrated circuit device according to an embodiment of the present invention.

FIG. 4 is a perspective view showing an anisotropic conductive member used in a method for connecting a semiconductor integrated circuit device according to an example of the present invention.

FIG. 5 is a perspective view showing a conductive connector used in a method for connecting a semiconductor integrated circuit device in an example of the present invention.

FIG. 6 is a sectional view showing an embodiment in which the method for connecting a semiconductor integrated circuit device of the present invention is applied to a liquid crystal display device.

FIG. 7 is a cross-sectional view showing a method of connecting a conventional semiconductor integrated circuit device.

[Explanation of symbols]

 102 semiconductor integrated circuit piece (IC chip) 110 connection electrode 112 conductive connection body 114 circuit board electrode 116 circuit board

Claims (7)

[Claims] 1. A semiconductor integrated circuit piece having a connection electrode,
A circuit board having a circuit board electrode, conductive particles having elasticity, or conductive particles and non-conductive particles having elasticity are kneaded together with an insulating adhesive to form a conductive connector, and the conductive particles or non-conductive particles are used. The circuit board electrode and the semiconductor integrated circuit piece are adhered to each other at particle diameter intervals of the conductive particles, and the connection electrode of the semiconductor integrated circuit piece and the circuit board electrode of the circuit board are electrically connected using a conductive connector. Method for connecting semiconductor integrated circuit device. 2. The semiconductor integrated circuit according to claim 1, wherein the circuit board is a liquid crystal element substrate in which a transparent conductive film is formed on glass, and the semiconductor integrated circuit piece is a liquid crystal driving integrated circuit element. Device manufacturing method. 3. The method of manufacturing a semiconductor integrated circuit device according to claim 1, wherein the conductive connector is a micro spring structure formed of a shape memory alloy. 4. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the conductive connector is a minute elastic plastic spring structure whose surface is conductively coated. 5. The conductive connecting body is a fine elastic plastic body having a conductive coating on the surface thereof, and further has a structure in which insulating thermoplastic fine powder is applied onto the elastic plastic body. Item 2. A method for manufacturing a semiconductor integrated circuit device according to item 1. 6. The semiconductor according to claim 1, wherein the conductive connector is a composite of cold-compressed shape memory alloy strips solidified with plastic, and has a structure in which the compression can be released by a temperature rise. Manufacturing method of integrated circuit device. 7. An anisotropic conductive member is used to connect the connection electrode of the IC chip and the circuit board electrode of the circuit board, and the anisotropic conductive member is formed by cold working deformation of a shape memory alloy. A spring structure, the side surface of the spring structure is covered with an insulating sheath, a large number of spring structures are bundled to form an anisotropic conductive member, and the semiconductor integrated circuit piece and the circuit board are anisotropically conductive members. A method for connecting a semiconductor integrated circuit device, comprising: fixing the semiconductor integrated circuit device by sandwiching it and heating it to generate a connection pressure for electrical connection in the anisotropic conductive member.