JP3505321B2 - Conductive fine particles and substrate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device such as a semiconductor,
The present invention relates to a substrate which is conductively bonded using conductive fine particles used for conductively bonding an electrode substrate or the like. 2. Description of the Related Art When manufacturing electronic devices such as liquid crystal display elements, conductive bonding has conventionally been performed in bonding an integrated circuit (LSI) semiconductor chip to a substrate having electrodes such as a liquid crystal display panel. Has been done. 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. JP, JP-A-62-161187, JP-A-62-161187
Japanese Patent No. 127194 discloses a material for conductively joining an electrode substrate and an electronic component such as a semiconductor chip by using solder. [0003] As a method for conducting conductive bonding using conductive fine particles, for example, Japanese Patent Application Laid-Open No. 62-41238 discloses a method in which nickel or nickel having a thickness of 0.1 to 5 µm is coated on the surface of a copper core. A conductive filler provided with a coating layer of an alloy is disclosed. Japanese Utility Model Application Laid-Open No. 62-86011 discloses solder-coated nickel particles. It is used as an adhesive when blended with molecular materials and paints. Japanese Patent Application Laid-Open No. 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, there has been proposed a method in which silver fine powder is mixed into an epoxy resin and conductive fine particles formed into a particle shape are used. In these techniques, metal spherical particles of copper, nickel or the like are used as a core, and fine particles whose surface is coated with a metal such as palladium or gold are used. However, when metal particles such as copper are used as the core, the conductive fine particles are hard and have poor elasticity, so that stress tends to concentrate on the joints, and there is a disadvantage that the reliability of the obtained electronic device is reduced. There are also problems such as the particle size distribution of the metal spherical particles that become the body being too wide, and the metal covering the surface being expensive. Further, when a mixture of silver fine powder in an epoxy resin is molded into particles and used, it is difficult to lower the electric resistance value. Further, at the time of joining, since an organic polymer material or the like is used as an adhesive, electrical connection is made by conductive fine particles, and mechanical connection is made by an organic polymer material or the like. The electronic components joined by the simple joining method have problems such as that when the temperature is high, the organic polymer material or the like thermally expands and the electrical connection becomes poor, and the electric resistance value increases. [0007] As a conductive bonding method without using an adhesive such as an organic polymer material, a ball grip array (B) is currently used.
GA), flip tics, etc., and solder particles are widely used as conductive fine particles. However, when the solder particles are joined by heating and melting, when the solder at the joining portion is easy to spread, the adjacent electrodes are easily short-circuited, and the gap between the electrode substrate and the electronic component such as a semiconductor chip changes, the solder particles are identified. There is a problem that a load is likely to be applied to the joint portion of the above. SUMMARY OF THE INVENTION In view of the above, the present invention satisfactorily performs bonding of elements such as an electrode substrate and a semiconductor chip, or of electrode substrates by a conductive bonding method such as BGA or flip tic. Can be, and conductive fine particles with excellent elasticity, as well as conductively joined using it,
An object of the present invention is to provide a substrate free from connection failure due to a thermal cycle. The above object can be achieved by conductive fine particles having a metal plating layer having solder wettability on the surface of base fine particles made of resin. Hereinafter, the present invention will be described in detail. The base particles used in the present invention are made of a resin. The resin is not particularly limited, for example, a phenol resin, an amino resin, an acrylic resin, a polyester resin, a urea resin, a melamine resin, an alkyd resin, a polyimide resin, a urethane resin, a cross-linked or non-cross-linked synthetic resin such as an epoxy resin. An organic-inorganic hybrid polymer and the like. The compression hardness (K value) of the base fine particles is 1
00-1000 kg / mm < ² > is preferable. 100kg /
If it is less than ² mm ^2, it is not practical and 1000 kg / m
If it exceeds m ² , it is too hard, and when used as conductive fine particles, stress is likely to be applied to the joint. Where K
The value is a value defined by the following equation (1), and represents universally and quantitatively the hardness of a sphere. K = (3 / √2) · F · S ^−3/2 / R ^−1/2 (1) In the formula, F represents a load value (kg) at 10% compressive deformation of the base fine particles, and S represents , The compression displacement (mm), R
Represents the radius (mm) of the particle. The average particle diameter of the base fine particles is 1 μm to
3 mm is preferred. If it is less than 1 μm, the electrode substrates may come into direct contact with each other to cause a short circuit, and if it exceeds 3 mm, it may be difficult to perform fine pitch electrode bonding. The conductive fine particles of the present invention 1 have a metal plating layer having solder wettability on the surface of the base fine particles. In the present specification, the solder wettability, the property of spreading the solder melted smoothly and smoothly without interruption, and, when heated, can form one liquid phase with the molten solder, It means a property that can be eutectic when cooled. The metal forming the metal plating layer having solder wettability is preferably a high melting point metal having good solder wettability.
Point solder is used. The melting point of the high melting point solder is 3
It is 00 ° C or higher. The thickness of the metal plating layer is 0.01 to 5
00 μm is preferred. When the thickness is less than 0.01 μm, when used for conductive bonding, the metal plating layer may be peeled off from the surface by heating, and furthermore, a preferable conductivity cannot be obtained because the thickness of the conductive plating layer is thin. is there.
On the other hand, if it exceeds 500 μm, the thickness of the conductive plating layer becomes too large, and the mechanical properties of the base particles may be lost. When a high melting point solder is used as the metal forming the metal plating layer, the thickness of the metal plating layer is set to 0.1 mm.
It is preferably from 01 to 100 μm. The method for forming the metal plating layer is not particularly limited, and examples thereof include electroless plating, hot dipping, diffusion plating, electroplating, thermal spraying, and vapor deposition. The metal plating layer can be formed by using these methods alone or by combining them. The conductive fine particles according to the first aspect of the present invention include the above-described metal mesh.
It has an underlying plating layer. The metal forming the base plating layer is not particularly limited, and examples thereof include nickel. Since the conductive fine particles of the present invention 1 use resin particles as the base fine particles, they have excellent elasticity, and when used for conductive bonding, stress is not easily applied to the bonding portion. The distance between the substrates and the like can be kept constant. Further, it is possible to reduce a shear stress due to a relative position shift between the electrodes due to thermal expansion and contraction of the electrode substrate and the element due to a temperature change. Further, the conductive fine particles of the present invention 1 have a metal plating layer having solder wettability on the surface of the base fine particles. Since the conductive fine particles of the present invention 1 are sufficiently adhered to the electrode substrate and the like to which the crystal solder permeates and are bonded, the contact resistance value can be kept at an extremely low level. The present invention 1 provides a device and an electrode substrate, or 2
This is a substrate formed by conductively bonding at least one electrode substrate.
The element is not particularly limited, and examples 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, and the like, on the surface of which an electrode is formed with ITO or the like. In the conductive bonding, a bonding portion between the element and the electrode substrate or a bonding portion between the two or more electrode substrates is bonded via the conductive fine particles. The method of the conductive bonding is not particularly limited, and examples thereof include BGA and flip tic. The conductive joining can be performed, for example, as follows. The cream solder is screen-printed on the bonding portion of the LSI semiconductor chip with a thickness of 50 to 80 μm. The conductive fine particles of the present invention 1 are placed thereon, and an electrode substrate on which cream solder is screen-printed is bonded to the bonding portion in the same manner as the above-mentioned LSI semiconductor chip, and heated at about 300 ° C. for bonding. Here, the substrate of the present invention 1 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. An LSI semiconductor chip 1 is connected to the ceramic plate 2. The conductive fine particles 4 according to the present invention 1
Conductive fine particles. Between the Cu electrode 3 on the ceramic plate 2 side and the Cu electrode 3 on the glass fiber reinforced epoxy resin plate 6 side, conductive fine particles 4 are adhered by eutectic solder 5. In addition, not only the electrode substrates but also the connection between the LSI semiconductor chip 1 and the ceramic plate 2 may be conductively bonded using the conductive fine particles 4. In the substrate according to the second aspect of the present invention, the contact portion between the element such as an LSI semiconductor chip or the electrode substrate and the conductive fine particles is sufficiently bonded by eutectic solder, so that the contact resistance value is kept at an extremely low level. It is possible to prevent the adjacent electrodes from being short-circuited without spreading the solder at the joint. 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 Crosslinked copolymer fine particles comprising divinylbenzene and tetramethylolmethanetetraacrylate (weight ratio: 1/1) were used as base particles (average particle diameter: 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 27 g of the fine particles, high melting point solder plating was performed by the electroplating apparatus shown in FIG. As the plating bath, an aqueous solution having a composition of 11.5 g / L of lead and 3.5 g / L of tin was used, a bath voltage of 11.6 V, and a current density of 2 A / dm.
Under the conditions of ² , plating was performed for 5 minutes. As a result, 5μ
Conductive fine particles having a m-thick solder layer were obtained. A cream solder having a thickness of 80 μm was formed by screen printing on the Cu electrode portion of the glass fiber reinforced epoxy resin electrode substrate shown in FIG. Next, the conductive fine particles were disposed thereon. Similarly,
The electrode substrates made of ceramic to which cream solder was applied were overlapped with each other so that the electrode portions faced each other, and were joined while being heated to 300 ° C. The conductive bonding state between both substrate electrodes was good, and a heat cycle test at -40 ° C / 120 ° C
No performance degradation was observed after 000 cycles. Example 2 Example 1 except that the nickel plating time was 9 minutes.
The plating was carried out under the same conditions as described above. As a result, conductive fine particles having a solder layer having a thickness of 11 μm were obtained. As a result of performing a substrate bonding test in the same manner as in Example 1 using these fine particles, the conductive bonding state between the two substrate electrodes was good, and −40.
Even after 1000 cycles of the thermal cycle test of 120 ° C./120° C., no deterioration in performance was observed. Comparative Example 1 Crosslinked copolymer fine particles comprising divinylbenzene and tetramethylolmethanetetraacrylate (weight ratio: 1/1) were used as base particles (average particle diameter: 650 μm,
Standard deviation 19 μm). 0.18 by electroless plating
A nickel layer having a thickness of μm was formed. Using these fine particles, a 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, on this,
The nickel-coated fine particles were arranged. Similarly, a ceramic electrode substrate to which cream solder was applied was overlapped in an arrangement in which the electrode portions face each other, and joined while heating to 300 ° C. The conductive bonding state between the two substrate electrodes was poor, and the cause was investigated. It was found that the nickel plating layer was peeled off from the substrate surface due to the action of the flux in the cream solder during heating. Was. 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 substrate can be joined well, and the connection failure due to the heat cycle is reduced. Therefore, the present invention can be suitably used for manufacturing a liquid crystal display element or the like in which an electronic component such as an LSI semiconductor chip and an electrode substrate are conductively joined.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view illustrating 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. [Description of Signs] 1 LSI semiconductor chip 2 Ceramic plate 3 Cu electrode 4 Conductive fine particles 5 Eutectic solder 6 Glass fiber reinforced epoxy resin plate 11 Cover 12 Electrode 12a anode 13 Rotating shaft 14 Cover 15 Container 16 Plating solution supply pipe 17 Plating Liquid discharge pipe 18 Opening 21 Bottom plate 22 Contact ring (cathode) 23 Porous ring

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-242010 (JP, A) JP-A-7-50104 (JP, A) JP-A-5-36306 (JP, A) JP-A-7-104 157720 (JP, A) JP-A-62-177082 (JP, A) JP 2000-507047 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 1/00, 5 / 00 H01L 23/12 H01R 11/01 H05K 3/32-3/36

Claims (1)

(57) Claims 1. An element and an electrode substrate, or a substrate formed by conductively bonding two or more electrode substrates, wherein the conductive junction is formed by the element and the electrode substrate. The junction, or
The bonding portion of the two or more electrode substrates is a conductive fine particle having a base plating layer and a metal plating layer having solder wettability on the surface of a base fine particle made of a resin, wherein the metal plating layer Wherein the substrate is joined by eutectic solder formed at the joint portion via conductive fine particles, which are high melting point solder layers having a melting point of 300 ° C. or higher.