JPH09306231A - Conductive particulate and substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bonding between semiconductor chips or electrode substrates and elasticity thereof and prevent contact failures due to a thermal cycle by using a conductive particulate in which a nickel plating layer is applied to the bonding face. SOLUTION: A ceramic plate 2 and a glass fiber reinforce epoxy plate 3 having Cu electrodes 3, respectively, are conducted and bonded using a conductive particulate 4 and constitutes a substrate. An LSI chip 1 is connected to the ceramic plate 2. A cream solder 5 is applied to the respective Cu electrodes 3, and the conductive particulate 4 are adhered therebetween. A bonding part between the LSI semiconductor chip 1 and the ceramic substrate 2 may be conducted and bonded using the conductive particulate 4. A nickel plating layer of 0.5 to 100μm in thickness may be applied to the surface of the conductive particulate 4. Further, a solder plating layer may be applied to that plating layer. In this case, there is no need for using the cream solder 5.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an element such as a semiconductor,
The present invention relates to conductive fine particles used for conductively bonding an electrode substrate and the like, and a substrate conductively bonded using the same.

[0002]

2. Description of the Related Art When manufacturing an electronic device such as a liquid crystal display element, conductive bonding has been conventionally performed for bonding an integrated circuit (LSI) semiconductor chip and a substrate having electrodes such as a liquid crystal display panel. . As a material used for conductive bonding, for example, JP-A-62-61204 discloses a conductive adhesive sheet obtained by kneading a solder alloy and a plastic material, and JP-A-62-61396. JP-A-62-161187, JP-A-62-1816
Japanese Patent No. 127194 discloses a material for conductively bonding an electrode substrate and an electronic component such as a semiconductor chip by using solder.

Further, as a method for conductively bonding by using conductive fine particles, for example, in JP-A-62-41238, nickel or nickel having a thickness of 0.1 to 5 μm is formed on the surface of a core body made of copper. A conductive filler provided with an alloy coating layer is disclosed, and Japanese Utility Model Laid-Open No. 62-86011 discloses solder-coated nickel particles. Used as an adhesive by blending with molecular materials and paints.

JP-A-62-199611 discloses a conductive composition containing spherical particles having a conductive outer surface made of a metal selected from platinum, palladium and gold. JP-A-246705 and JP-A-1-246706 disclose a conductive paste containing spherical fine particles having a layer made of an oxidation resistant metal such as silver, nickel, gold or palladium on the surface of copper particles. . In addition to this, a method has also been proposed in which fine silver powder is mixed in an epoxy resin and conductive fine particles formed into particles are used.

In these techniques, spherical particles of metal such as copper and nickel are used as a core, and fine particles whose surface is coated with metal such as palladium and gold are used. However, when metal particles such as copper are used as the core body, the conductive fine particles are hard and have poor elasticity, so that stress is likely to be concentrated at the joint portion, and there is a drawback that the reliability of the obtained electronic device is deteriorated. There are also problems that the particle size distribution of the metallic spherical particles forming the body becomes too wide, and that the metal coating the surface is expensive. Further, if a mixture of fine silver powder in an epoxy resin is molded into particles and used, it is difficult to reduce the electric resistance value.

Furthermore, since an organic polymer material or the like is used as an adhesive at the time of joining, the conductive fine particles make an electrical connection, and the organic polymer material or the like makes a mechanical connection. The electronic components joined by various joining methods have problems that the organic polymer material or the like thermally expands at a high temperature to cause a poor electrical connection or an increase in the electrical resistance value.

As a conductive bonding method which does not use an adhesive such as an organic polymer material, a ball grip array (B
GA) and flip-ticking are performed, and solder particles are widely used as conductive fine particles. However, when the solder particles are heated and melted to be joined, the solder at the joining portion is likely to spread, the adjacent electrodes are easily short-circuited, and the distance between the electrode substrate and the electronic component such as the semiconductor chip is changed. However, there is a problem that a load is likely to be applied to the joint portion of.

[0008]

In view of the above, the present invention can satisfactorily bond elements such as an electrode substrate and a semiconductor chip, or electrode substrates to each other by a conductive bonding method such as BGA or flip tic. , And conductive fine particles having excellent elasticity, and conductively bonded using the same,
It is an object of the present invention to provide a substrate that does not have a connection failure due to thermal cycles.

[0009]

The above-mentioned object is to provide conductive fine particles (hereinafter referred to as “conductive fine particles (1) which have a nickel plating layer having a thickness of 0.5 to 100 μm) on the surface of base fine particles made of resin. ) ”.) Can be achieved. The above object can also be achieved by conductive fine particles (hereinafter, referred to as "conductive fine particles (2)") having a solder plating layer on the surface of the conductive fine particles (1). Hereinafter, the present invention will be described in detail.

The base fine particles used in the present invention are made of resin. The resin is not particularly limited, and examples thereof include cross-linked or non-cross-linked synthetic resins such as phenol resin, amino resin, acrylic resin, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, urethane resin, and epoxy resin. An organic-inorganic hybrid polymer and the like can be mentioned.

The compression hardness (K value) of the base fine particles is 1
It is preferably from 00 to 1000 kg / mm ² . 100kg /
If it is less than mm ^2, it is not practical and 1000 kg / m
When it exceeds m ² , it is too hard and when used as conductive fine particles, stress tends to be applied to the joint portion. Here, the K value is a value defined by the following formula (1), which universally and quantitatively represents the hardness of a sphere. K = (3 / √2) · F · S ^−3/2 / R ^−1/2 (1) In the formula, F represents the load value (kg) at 10% compressive deformation of the base fine particles, and S is , Compression displacement (mm), R
Represents the radius (mm) of the particle.

The average particle diameter of the base fine particles is from 1 μm to
3 mm is preferred. If it is less than 1 μm, the electrode substrates may directly contact each other to cause a short circuit. If it exceeds 3 mm, it may be difficult to bond the fine pitch electrodes.

The conductive fine particles (1) of the present invention 1 have a thick nickel plating layer on the surface of the base fine particles. The nickel plating layer has a thickness of 0.5 to 100 μm.
If it is less than 0.5 μm, when used for conductive bonding,
The heating may cause the plating layer to peel off from the surface,
In addition, the conductive plating layer may have a small thickness, so that preferable conductivity may not be obtained. On the other hand, when it exceeds 100 μm, the thickness of the conductive plating layer becomes too thick and the mechanical properties of the base fine particles may be lost, so the range is limited to the above range.

The method of forming the nickel plating layer is not particularly limited, and examples thereof include electroless plating, hot dipping,
Diffusion plating, electroplating, thermal spraying, vapor deposition and the like can be mentioned.
The nickel plating layer can be formed by using these methods alone or by combining these methods. For example, first, electroless nickel plating is performed on the base fine particles to form a nickel plating layer having a thickness of 0.01 to 0.3 μm, and then electric nickel plating is performed,
Examples include a method of forming a nickel plating layer having a thickness of 0.5 to 100 μm.

Since the conductive fine particles (1) of the present invention 1 use resin particles as the base fine particles, they are excellent in elasticity and are less likely to be stressed at the joint portion when used for conductive joining. In addition, since the base material fine particles have a nickel thick film plating layer on the surface, the resin forming the base material fine particles does not affect the electric resistance value, and conductive bonding of elements such as LSI semiconductor chips and electrode substrates is achieved. Can be suitably used.

The conductive fine particles (2) of the present invention 1 have a solder plating layer on the surface of the conductive fine particles (1). The thickness of the solder plating layer is preferably 5 to 30 μm.
If it is less than 5 μm, the conductive fine particles may not be sufficiently bonded to the element or the electrode substrate, and if it exceeds 30 μm,
Excessive solder may spread during heating and melting, resulting in a short circuit of the electrodes.

The method for forming the solder plating layer is not particularly limited, and examples thereof include electroplating.

Since the conductive fine particles (2) of the present invention 1 have a solder plating layer on the surface of the conductive fine particles (1), when used for conductive bonding of an element such as an LSI semiconductor chip or an electrode substrate, Even if the joint surface is not suitable for screen-printing solder, the element and the electrode substrate or the electrode substrates can be well joined.

The present invention 2 is directed to an element and an electrode substrate, or 2
It is a substrate formed by conductively bonding at least one electrode substrate.
The element is not particularly limited, and examples thereof include an LSI semiconductor chip and a capacitor chip. The electrode substrate is not particularly limited, and examples thereof include a glass plate, a ceramic plate, a synthetic resin plate, etc., on the surface of which electrodes are formed of ITO or the like.

In the conductive bonding, the bonding portion between the element and the electrode substrate or the bonding portion between the two or more electrode substrates is connected through the conductive fine particles (1) or the conductive fine particles (2). It is joined. The conductive bonding method is not particularly limited, and examples thereof include BGA and flip-tic. The conductive bonding can be performed as follows, for example. 50-80 μm of cream solder on the joint of LSI semiconductor chip
Screen print with the thickness of. On top of that, the conductive fine particles (1) or the conductive fine particles (2) of the present invention 1 are arranged, and the electrode substrate having the cream solder screen-printed on the bonding portion is laid on it in the same manner as the above-mentioned LSI semiconductor chip.
Heat and bond at 0 ° C.

Alternatively, the conductive particles (2) of the present invention 1 may be placed directly on the bonding portion of the LSI semiconductor chip, the electrode substrates may be overlapped and heated to about 300 ° C. to conduct the conductive bonding.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Here, the substrate of the present invention 2 will be described in detail with reference to the drawings. FIG. 1 shows a substrate in which a ceramic plate 2 having a Cu electrode 3 and a glass fiber reinforced epoxy plate 6 having a Cu electrode 3 are conductively bonded using conductive fine particles 4. The LSI semiconductor chip 1 is connected to the ceramic plate 2. The conductive fine particles 4 are bonded by the cream solder 5 between the Cu electrode 3 on the ceramic plate 2 side and the Cu electrode 3 on the glass fiber reinforced epoxy plate 6 side. Also, not only the electrode substrates but also L
The connection part between the SI semiconductor chip 1 and the ceramic plate 2 is also
It may be conductively bonded by using the conductive fine particles 4.

In FIG. 1, the conductive fine particles 4 have a nickel thick film plating layer on the surface, but in the present invention, as the conductive fine particles, a nickel thick film plating layer is formed on the nickel thick film plating layer. Further, one having a solder plating layer may be used. In this case, it is not necessary to use cream solder.

Since the substrate of the present invention 2 does not use more solder than necessary at the portion where the element such as the electrode substrate or the LSI semiconductor chip comes into contact with the conductive fine particles, the solder at the joint portion does not spread and is adjacent to each other. It does not short the electrodes.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

EXAMPLE 1 Copolymerized crosslinked fine particles of divinylbenzene and tetramethylolmethane tetraacrylate (weight ratio 1/1) were used as base fine particles (average particle size 650 μm,
Standard deviation 19 μm). 0.18 by electroless plating
A nickel layer having a thickness of μm was formed as a base plating layer.
Using 50 g of these fine particles, nickel thick film plating was performed by the electroplating apparatus shown in FIG. The plating bath was an aqueous solution of nickel sulfate, and the bath voltage was 25 V and the current density was 1.
As a result of plating for 24 minutes under the condition of 0 A / dm ² , conductive fine particles having a nickel layer with a thickness of 5 μm were obtained.

Cream solder having a thickness of 80 μm was formed on the Cu electrode portion of the glass fiber reinforced epoxy resin electrode substrate shown in FIG. 1 by screen printing. Then, the above conductive fine particles were arranged on this. Similarly,
The ceramic electrode substrates coated with cream solder were placed one on top of the other with their electrode parts facing each other, and joined while heating at 300 ° C. The conductive connection between both substrate electrodes is good, and the thermal cycle test at -40 ° C / 120 ° C
No performance deterioration was observed after 000 cycles.

Example 2 The nickel plating bath had a bath voltage of 26 V and a current density of 1.3.
Plating was performed in the same manner as in Example 1 except that A / dm ² and the energization time were 37 minutes. As a result, conductive fine particles having a nickel layer with a thickness of 12 μm were obtained. As a result of carrying out a substrate bonding test similar to that of Example 1 using these fine particles, the conductive bonding state between both substrate electrodes was good, and -40
No deterioration in performance was observed even after 1000 cycles of the heat cycle test of ° C / 120 ° C.

Example 3 The conductive fine particles having a nickel layer of 5 μm thick obtained in Example 1 were again formed with a solder layer on the outer periphery thereof by the electroplating apparatus shown in FIG. The plating conditions at this time are
26 g of fine particles were used, the current density was 2 A / dm ² , and the energization time was 8 minutes. The solder composition was 60 wt% Sn and 40 wt% Pb. As a result, conductive fine particles having a solder layer with a thickness of 11 μm on the outer periphery of the nickel layer of 5 μm were obtained. As a result of carrying out a substrate bonding test similar to that of Example 1 using these fine particles, the conductive bonding state between both substrate electrodes is good, and even after 1000 cycles of the −40 ° C./120° C. thermal cycle test, No performance deterioration was observed.

Comparative Example 1 Copolymerized crosslinked fine particles composed of divinylbenzene and tetramethylolmethane tetraacrylate (weight ratio 1/1) were used as base material fine particles (average particle diameter 650 μm,
Standard deviation 19 μm). 0.35 by electroless plating
A μm thick nickel layer was formed. Using these fine particles, cream solder having a thickness of 80 μm was formed on the Cu electrode portion of the glass fiber reinforced epoxy electrode substrate shown in FIG. 1 by screen printing. Then, the above nickel-coated fine particles were arranged on this. Similarly, the ceramic electrode substrates coated with cream solder were superposed on each other such that their electrode portions face each other, and joined while heating at 300 ° C. The conductive connection between both board electrodes is poor,
When the cause was investigated, it became clear that the nickel plating layer was peeled from the substrate surface due to the action of the flux in the cream solder during heating.

Comparative Example 2 The fine particles having a nickel layer having a thickness of 0.35 μm obtained in Comparative Example 1 were formed with a solder layer on the outer periphery thereof by the electroplating apparatus shown in FIG. The plating conditions used at this time were 30 g of fine particles, a current density of 2 A / dm ² and an energization time of 1
0 minutes. The solder composition was 60 wt% Sn and 40 wt% Pb. As a result, 0.35 μm
Conductive fine particles having a solder layer with a thickness of 12 μm on the outer periphery of the nickel layer were obtained. Using these fine particles, a substrate joining test was conducted in the same manner as in Comparative Example 1. The conductive joint state between both board electrodes is poor, and when the cause was investigated,
By the action of the flux in the cream solder during heating,
It was clear that peeling of the nickel plating layer from the surface of the base material occurred.

[0032]

EFFECTS OF THE INVENTION Since the conductive fine particles and the substrate of the present invention have the above-mentioned constitution, the electrode substrate and the element, or the electrode substrates can be satisfactorily bonded to each other, and there is no connection failure due to the thermal cycle. It can be suitably used for manufacturing a liquid crystal display element or the like in which an electronic component such as a semiconductor chip and an electrode substrate are conductively joined.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a substrate of the present invention.

FIG. 2 is a cross-sectional view of an electroplating apparatus used when producing the conductive fine particles of the present invention.

[Explanation of symbols]

 1 LSI Semiconductor Chip 2 Ceramic Plate 3 Cu Electrode 4 Conductive Fine Particles 5 Cream Solder 6 Glass Fiber Reinforced Epoxy Plate 10 Electroplating Device 11 Anode 12 Cathode 13 Plating Liquid Supply Pipe 14 Electrode 15 Rotating Shaft 16 Plating Liquid Discharge Pipe 17 Filter 18 Units Wood particles

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H05K 3/36 H05K 3/36 A

Claims (3)

[Claims] 1. A conductive fine particle comprising a base fine particle made of a resin and having a nickel plating layer having a thickness of 0.5 to 100 μm on the surface. 2. A conductive fine particle having a solder plating layer on the surface of the conductive fine particle according to claim 1. 3. An element and an electrode substrate, or a substrate in which two or more electrode substrates are conductively bonded, wherein the conductive bonding is a bonding portion of the element and the electrode substrate, or
The joint portion of the two or more electrode substrates is formed according to claim 1 or 2.
A substrate which is bonded via the conductive fine particles described in the above.