JPH0779192B2 - How to join electronic components - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for joining electronic components in which electronic components are directly joined to a wiring board surface.

[Technical background of the invention]

As a method of attaching electronic components such as an LSI chip and a liquid crystal display panel to a wiring board, there is a method of directly bonding the electronic components to the wiring board surface.

In this method, conventionally, a plurality of electronic component connecting terminals corresponding to a plurality of external circuit connecting terminals formed on the wiring substrate connecting surface of the electronic component are arranged and formed on the electronic component connecting surface of the wiring substrate surface. , An electronically conductive adhesive is applied to the electronic component bonding surface of the wiring board from above each electronic component connecting terminal, and the electronic component is overlaid thereon, and in this state, the electronic component and the wiring board are relatively A method has been adopted in which the terminals of the electronic component and the wiring board are electrically connected to each other by being pressed so as to be adhesively joined.

The anisotropic conductive adhesive is a mixture of electrically conductive particles in an insulating adhesive in such a ratio that the conductive particles do not contact each other, and is made of this anisotropic conductive adhesive. Since the adhesive layer has conductivity in the thickness direction but has insulating property in the surface direction (lateral direction), the anisotropic conductive adhesive is interposed between the electronic component and the wiring board to form an electronic layer. When the component and the wiring board are relatively pressed, each terminal of the electronic component and each terminal of the wiring board are electrically connected (electrically connected via conductive particles).

[Problems of background technology]

However, in the method of adhesively bonding the electronic component and the wiring board with the anisotropic conductive adhesive, the electronic component can be attached to the wiring board in a short time.
Not all of the terminals of the electronic component and the terminals of the wiring board are all necessarily electrically connected, and there is the problem of poor reliability.

This is because the distribution of the conductive particles of the anisotropic conductive adhesive is irregularly distributed, whereas the electronic width of electronic parts such as LSI chips and liquid crystal display panels is very narrow, If the anisotropic conductive adhesive has a portion where the distance between the conductive particles is wider than the terminal width, and the terminal happens to correspond to this portion, the conductive portion between the electronic component and the wiring board is electrically conductive in this portion. The conductive particles are not interposed and the terminals in this portion are not electrically connected. If the mixing ratio of the conductive particles in the anisotropic conductive adhesive is increased, the distance between the conductive particles also becomes smaller, so that all the terminals can be almost surely conductively connected. If the mixing ratio of conductive particles in the one-way conductive adhesive is increased,
In a portion where the conductive particles are closely spaced, the conductive particles come into contact with each other and short-circuit adjacent terminals.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the invention is to efficiently and efficiently electronic parts in a short time comparable to the method of adhesively bonding electronic parts with an anisotropic conductive adhesive. To provide a method for joining electronic components, in which each of the terminals of the electronic component can be securely connected to each other on the surface of the substrate so that a defective conduction portion is generated. is there.

[Outline of Invention]

The method for joining electronic components according to the present invention is such that after applying an insulating adhesive to one of the joining surfaces of the electronic component and the wiring board, a mesh screen is overlaid on the insulating adhesive and conductivity is applied from above. Particles are scattered, and among the conductive particles, the conductive particles that have entered each opening of the mesh screen are pushed into the insulating adhesive to embed a large number of conductive particles in the insulating adhesive at equal intervals. After that, the electronic component and the wiring board are overlapped and relatively pressed to bond and bond the electronic component and the wiring board.

That is, according to the present invention, the electronic component and the wiring board are adhesively joined via the joining material in which the conductive particles are embedded in the insulating adhesive, so that the electronic component is adhesively joined by the anisotropic conductive adhesive. Similar to the method, it is possible to bond the electronic component to the wiring substrate in a state where both terminals are electrically connected to each other only by relatively pressing the electronic component and the wiring substrate to cure the adhesive. In addition, the conductive particles are provided with a large number of openings smaller than the width of a narrow terminal of both terminals of the electronic component and the wiring board and smaller than any terminal spacing between the electronic component and the wiring board. Is embedded in the insulating adhesive through a mesh screen formed at equal intervals with a width smaller than the width of the narrow terminals, so that at least one conductive particle must be interposed between all corresponding terminals. In the so that, those who lost the occurrence of poor conduction portion due to variation in the distribution of the conductive particles in the case of using an anisotropic conductive adhesive.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

First, the joining structure of electronic components will be described. In FIGS. 1 to 3, 1 is a wiring board, and a plurality of wirings 2, 2, ... Are provided on the surface of the wiring board 1 as shown in FIG. Has been formed. The wirings 2, 2, ... Are derived from the LSI chip joint portion of the wiring board 1, and the ends of the wirings 2, 2 ,. For forming a plurality of external circuit connection terminals 11, 11, ...
And corresponding LSI chip connection terminals 2a, 2a ,. The width of each terminal 2a, 2a, ... Is slightly narrower than the width of each terminal 11, 11 ,.

3 is a bonding material formed on the LSI chip bonding surface of the substrate 1 so as to cover all the LSI chip bonding terminals 2a, 2a, ..., and this bonding material 3 is formed on the LSI chip bonding surface. A large number of conductive particles 4, 4, ... Are embedded in an insulating adhesive 3a uniformly applied over the entire surface. The conductive particles 4, 4, ... Are the external circuit connection terminals 1 of the LSI chip 10.
, 1, and terminals 2a, 2a, ... for connecting LSI chips on the surface of the wiring board 1
And the narrow terminal (in this embodiment, the wiring board 1 surface
The width of the LSI chip connection terminals 2a, 2a, ..., And the particle size smaller than the interval between the external circuit connection terminals 11, 11, ... of the LSI chip 10 (for example, the terminal width and the interval are 50 to 250 μ). In this case, the particle size is 20-40μ).
4, are embedded in the insulating adhesive 3 at regular intervals smaller than the width of the terminals 2a, 2a ,. The conductive particles 4, 4, ... Are, for example, nickel particles plated with gold, solder particles, copper particles plated with gold or silver, or graphite particles.

Further, in FIG. 3, 2b, 2b, ... Are a plurality of external circuit connecting terminals 21 arranged on one side edge portion of the wiring board 1 on the wiring board joint surface (terminal arrangement portion) of the liquid crystal display panel 20. ,twenty one,
The display panel connection terminals are arranged correspondingly to the display panel connection terminals, and the display panel connection terminals 2b, 2b, .. The maximum particle size of the conductive adhesive is smaller than the width of the narrower one of the display panel connecting terminals 2b, 2b, ... And the external circuit connecting terminals 21, 21 ,. Is smaller than the width of the narrow terminals 2b, 2b, ... And the conductive particles are smaller than any of the terminal intervals of the display panel connecting terminals 2b, 2b, ... And the external circuit connecting terminals 21, 21 ,. The bonding material 3 is formed so as to be embedded at equal intervals with a small interval.

In the LSI chip 10, the external circuit connection terminals 11, 11, ... Are connected to the LSI chip connection terminals 2a, 2 on the surface of the wiring board 1.
By stacking on the bonding material 3 corresponding to a, ..., By relatively pressing the LSI chip 10 and the wiring substrate 1 and curing the insulating adhesive 3a of the bonding material 3 in that state, First
As shown in FIG. 2 and FIG. 2, each terminal 11,
, And the terminals 2a, 2a, ... Of the wiring board 1 are adhesively joined by the insulating adhesive 3a in a state in which they are electrically connected by the conductive particles 4, 4 ,.

In FIG. 1 and FIG. 2, reference numeral 18 is a molding resin such as epoxy resin for molding the LSI chip 10 bonded to the wiring board 1, and the molding resin 18 is applied after the bonding of the LSI chip 10. . In addition, in FIG.
12 is the base material of the LSI chip 10 (here, N-type base material), 13 is P
The diffusion layers 13 and 14 are N-type diffusion layers.
An insulating film 15 made of silicon oxide (SiO ₂ ) is formed on the main surface of the chip where is formed, and a wiring 16 made of aluminum is formed thereon. The wiring 16 is electrically connected to a predetermined diffusion layer of the diffusion layers 13 and 14 in the opening provided in the insulating film 15, and the pad portion 16a formed at the lead-out end of the wiring 16 is externally exposed as it is. Circuit connection terminal 1
It is supposed to be 1. Reference numeral 17 denotes an insulating protective film made of silicon oxide that covers the wiring 16, and the protective film 17 is used for the terminal 2a.
It is formed on the entire surface of the chip except for the portion.

Further, in the liquid crystal display panel 20, the bonding material 3 whose wiring board bonding surface is formed on the display panel bonding surface of the wiring board 1 is used.
It is bonded and bonded to the wiring board 1 in the same manner as the LSI chip 10 by stacking and pressing on the above and curing the insulating adhesive 3a of the bonding material 3.

Next, the procedure for joining the electronic components to the wiring board 1 will be described below.
Bonding of the LSI chip 10 will be described with reference to FIG.

First, the wiring board 1 surface on which the wirings 2, 2, ..., LSI chip connecting terminals 2a, 2a, .. and display panel connecting terminals 2b, 2b ,. The adhesive 3a is applied to a uniform thickness as shown in FIG. Incidentally, this insulating adhesive 3a, the conductive particles 4, 4,
Depending on the particle size of the largest particle, for example, when the particle size of the largest particle is 40μ, the layer thickness on terminals 2a, 2a is 40-60μ
Apply so that it becomes the extent.

Next, on the coating layer of this insulating adhesive 3a, as shown in FIG.
The mesh screen 5 is placed as shown in FIG. The mesh screen 5 is made of resin fiber such as tetron or a thin plate of stainless steel or the like in which fine openings are formed by etching or the like.
Is larger than the particle diameter of the largest particle among the conductive particles 4, 4, ... And the external circuit connecting terminals 11, 11, of the LSI chip 10,
, And the narrower terminals of the LSI chip connection terminals 2a, 2a, ... on the wiring board 1 surface (in this embodiment, the LSI on the wiring board 1 surface
Width of chip connection terminals 2a, 2a,…) and each of these terminals 2a, 2
A large number of openings 5a, 5a, ..., Which are smaller than the intervals between a. In addition, this mesh screen 5
The thickness of is almost the same as the particle diameter of the conductive particles 4 having the maximum diameter,
Or slightly thicker than that.

After that, as shown in FIG. 4 (c), the conductive particles 4, 4, ...
Is sprayed to a substantially uniform thickness, and then, as shown in FIG. 4 (d), pressure is applied by a pressure jig such as a roller 6 to enter the openings 5a, 5a, ... Of the mesh screen 5. The conductive particles 4, 4, ... Are pushed into the insulating adhesive 3a.
In this case, if all the particle diameters of the conductive particles 4, 4, ... Are the maximum particle diameters, one conductive particle 4, 4, ... Is inserted in each opening 5a, 5a ,. One conductive particle 4,4, ... Is pressed into the insulating adhesive 3a at equal intervals, but making the particle size of the conductive particles 4,4 ,. Therefore, in this embodiment, the conductive particles 4, 4, ... Having a somewhat small diameter are also used. Therefore, when the conductive particles 4, 4, ... Are sprinkled on the mesh screen 5, the conductive particles 4 having the maximum diameter enter the openings 5a of the mesh screen 5 one by one and are pushed into the insulating adhesive 3a. A plurality of small-diameter conductive particles 4 enter the openings 5a of the mesh screen 5 and are pushed into the insulating adhesive 3a. Even in that case, the conductive particles 4,4, which are pushed into the insulating adhesive 3a, The intervals of ... become substantially equal.

After the conductive particles 4, 4, ... have been pushed into the insulating adhesive 3a in this way, the scattered conductive particles 4, 4, ... are sucked by vacuum suction and pushed into the insulating adhesive 3a. The conductive particles 4, excluding the conductive particles 4, 4, held by the insulating adhesive 3a
4, ... Are removed as shown in FIG. The removed conductive particles 4, 4, ... Are recovered and reused.

In this way, a large number of conductive particles 4,
After the bonding material 3 in which 4, ... Is embedded is formed, the mesh screen 5 is removed, and the LSI chip 10 and the external circuit connection terminals 11, 11 ... The LSI chip connection terminals 2a, 2a, ... on the surface are overlapped with each other and the LSI chip 10 and the wiring board 1 are relatively pressed (for example, L
The SI chip 10 is pressed) to electrically connect the terminals 11 and 2a of both the LSI chip 10 and the wiring board 1 by the conductive particles 4, and the insulating adhesive 3a is cured in this pressed state. The LSI chip 10 is adhesively bonded to the wiring board 1.

Although the method of joining the LSI chips 10 has been described here, the liquid crystal display panel 20 is also joined by the same method as described above.

The insulating adhesive 3a may be a room temperature curing type,
It may be a thermoplastic adhesive that is generally called a hot melt type, a thermosetting type, or a UV ink.If a room temperature curing type adhesive or UV ink is used as the insulating adhesive 3a, insulation Particles in conductive adhesive 3a
Immediately after the bonding material 3 is formed by embedding the bonding material 4, 4, ... The protective paper may be protected and the release paper may be peeled off at the time of joining the electronic parts to join the electronic parts immediately. When a thermoplastic adhesive or a thermosetting adhesive called hot melt type is used as the insulating adhesive 3a, the insulating adhesive is formed by a hot air drying oven or infrared rays after forming the bonding material 3. 3a to 70
It may be dried at a temperature of ˜130 ° C., and at the time of joining the electronic components, the electronic components may be overlaid on the bonding material 3 and heated and pressed at a temperature of 100 to 150 ° C. by a press jig or a pressure roller. .

Thus, in the above-mentioned joining structure, the electronic component such as the LSI chip 10 and the liquid crystal display panel 20 and the wiring board 1 are bonded to each other by the bonding material 3 in which the conductive particles 4, 4, ... Are embedded in the insulating adhesive 3a. Since they are adhesively bonded to each other by simply pressing the electronic component and the wiring board 1 relatively to cure the insulating adhesive 3a, the electronic component is electrically connected to the wiring board 1 at both terminals thereof. Therefore, the electronic components can be efficiently attached in as short a time as the method of adhesively joining the electronic components with the anisotropic conductive adhesive. Further, in this joint structure, the maximum diameter of the conductive particles 4, 4, ... Is smaller than the width of a narrow terminal of both terminals of the electronic component and the wiring board 1, and the electronic component and the wiring are It is made smaller than any terminal interval with the substrate 1, and the conductive particles 4, 4, ... Are embedded in the insulating adhesive 3a at equal intervals smaller than the width of the narrow terminal. Therefore, at least one conductive particle 4 is inevitably interposed between all corresponding terminals, and therefore conduction is caused by the uneven distribution of the conductive particles as in the case of using the anisotropic conductive adhesive. Since no defective portion is generated, each terminal of the electronic component can be surely electrically connected to each terminal of the wiring board 1 without generating a defective portion. Further, in the above-mentioned joining method, the mesh screen 5 is laid on the insulating adhesive 3a applied to the surface of the wiring substrate 1, and the conductive particles 4, 4, ... Of the particles 4, 4, ..., the openings 5a, 5a of the mesh screen 5
Since the conductive particles 4, 4, ... Entered inside are pushed into the insulating adhesive 3a to form the bonding material 3, the insulating adhesive is
It is possible to surely make the distribution of the conductive particles 4, 4, ... In 3a evenly spaced.

In the above embodiment, the bonding material 3 for adhesively bonding the electronic components is formed on the wiring board 1 side. However, as shown in FIG. 5, the bonding material 3 is bonded to the electronic components, for example, the wiring board of the LSI chip 10. The external circuit connection terminals 11, 11, ... Of the LSI chip 10 may have a bump 16b formed by plating gold or the like on the pad portion 16a shown in FIG. Fifth
The structure shown in the figure may be used.

Further, in the above embodiment, the bonding material 3 is interposed on the entire bonding surface between the wiring board 1 and the electronic component. However, the bonding material 3 may be interposed only in the terminal array portion. , Instead of applying to the wiring board 1 or electronic parts,
It may be formed into a sheet shape in advance and sandwiched between the wiring board 1 and the electronic component.

〔The invention's effect〕

According to the present invention, since the electronic component and the wiring board are adhesively joined via the joining material in which the conductive particles are embedded in the insulating adhesive, the electronic component is adhesively joined by the anisotropic conductive adhesive. The electronic component can be efficiently attached to the wiring board in a short time as long as the method, and the conductive particles have the narrow width of the terminals of both the electronic component and the wiring board and the narrow width terminal. By embedding a large number of openings, which are smaller than the intervals between them, in an insulating adhesive through mesh screens formed at equal intervals at intervals smaller than the width of the narrow terminals, at least between all corresponding terminals. Since one conductive particle is always interposed, the occurrence of defective conduction due to uneven distribution of conductive particles when an anisotropic conductive adhesive is used is eliminated, and each terminal of an electronic component is eliminated. It can be reliably conductively connected without causing conduction failure portions to the terminals of the substrate surface.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention.
1 is an enlarged sectional view taken along line BB in FIG. 3, FIG. 2 is an enlarged sectional view taken along line AA in FIG. 1, FIG. 3 is a perspective view of a wiring board and electronic parts, FIG. 4 is a sectional view taken along the terminal arrangement line of the wiring board, showing the method of joining electronic components in the order of steps.
FIG. 5 is a sectional view taken along the terminal arrangement line of the wiring board and the electronic component showing another embodiment of the present invention. 1 ... Wiring board, 2 ... Wiring, 2a ... LSI chip connection terminal, 2b ... Display panel connection terminal, 3 ... Bonding material, 3a
Insulating adhesive, 4 conductive particles, 5 mesh screen, 5a opening, 6 roller, 10 LSI chip, 11 external circuit connection terminal, 20 liquid crystal display Panel, 21 ... External circuit connection terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hisashi Masaki Hisashi Masaki 3-2-1, Sakaemachi, Hamura-cho, Nishitama-gun, Tokyo Casio Computer Co., Ltd. Hamura Technical Center (72) Inventor Yoshio Akita Sakae-cho, Hamura-cho, Nishitama-gun, Tokyo 3-2-1, Casio Computer Co., Ltd., Hamura Technology Center (72) Inventor Yoshinori Atsumi 3-2-1, Sakaemachi, Hamura-cho, Nishitama-gun, Tokyo Casio Computer Co., Ltd., Hamura Technology Center (72) Inventor Tamaki Toshiharu 3-2-1 Sakaemachi, Hamura-cho, Nishitama-gun, Tokyo Casio Computer Co., Ltd., Hamura Technical Center (56) References JP-A-51-21192 (JP, A)

Claims (1)

[Claims] 1. An electronic component having a plurality of external circuit connecting terminals formed on a joint surface with a wiring board is directly attached to a wiring substrate surface having a plurality of electronic component connecting terminals corresponding to the respective terminals of the electronic component. In a method of joining electronic components to be joined, after applying an insulating adhesive to one of the joining surfaces of the electronic component and the wiring board, both the electronic component and the wiring board on the insulating adhesive A plurality of openings smaller than the width of the narrow terminals and smaller than any terminal spacing between the electronic component and the wiring board are formed at equal intervals smaller than the width of the narrow terminals. The mesh screens are overlapped, and the conductive particles are sprayed on the mesh screens. The conductive particles in the openings of the mesh screen among the conductive particles are pushed into the insulating adhesive to form the insulating adhesive. Multiple leads to Embedded sex particles at equal intervals, the joining method of the electronic component, characterized in that by relatively pressing superposed and said wiring board and the electronic component after the bonding bonding the wiring board and the electronic component.