JP3596572B2

JP3596572B2 - Board connection method

Info

Publication number: JP3596572B2
Application number: JP8814796A
Authority: JP
Inventors: 直行塩沢; 伊都夫渡辺; 治渡辺; 賢三竹村
Original assignee: Hitachi Chemical Co Ltd; Showa Denko Materials Co Ltd; Resonac Corp
Current assignee: Resonac Corp
Priority date: 1996-04-10
Filing date: 1996-04-10
Publication date: 2004-12-02
Anticipated expiration: 2016-04-10
Also published as: JPH09283566A

Description

【０００１】
【発明の属する技術分野】
本発明は、基板間の電気的な接続方法に関するもので、例えばＡｕバンプを有するＩＣチップと接続端子を形成した基板の接続に関するものである。
【０００２】
【従来の技術】
従来より集積回路類の配線基板への接続、表示素子類と配線基板への接続などのように、接続端子が相対峙して細かいピッチで形成されている場合の接続方法として、相対峙する接続端子間に金属粒子等の導電性粒子と接着剤成分からなる異方導電性の接続部材層を設け、加圧または加熱加圧手段を講じることによって、回路間の電気接続と同時に隣接回路間に絶縁性を付与し、相対峙する回路を接着固定する方法が用いられている。
しかしながら、これらの方法においては、導電性粒子を分散させた異方導電性の接続部材層を流動させながら接続するので、相対峙する電極間に配置される導電性の粒子は、接着剤と共に流動しながら電極間に挟み込まれる。電極間の導通は主として複数個の導電材料によって得られるものであり、狭ピッチ、微小電極の接続において電極上に複数個の導電性粒子材料を分布させ、かつ隣接する電極間の絶縁を維持することが困難になってきている。
【０００３】
【発明が解決しようとする課題】
本発明はかかる状況に鑑みなされたもので、さらに微細な電極の接続を達成すべく検討の結果本発明に達したものであり、接続部の電気特性の向上した微細電極の接続方法を提供することを目的とするものである。
【０００４】
【課題を解決するための手段】
本発明は、突起電極を有する第１の基板と、前記突起電極と相対峙する突起電極を有する第２の基板上の少なくとも一方の突起電極面に絶縁性の接着剤を突起電極の高さと同じまたは突起電極の高さより厚く配置するとともに、前記第１の基板と前記第２の基板の間に絶縁性を有する接着剤中に導電性の粒子が分散された異方導電性接着剤を配置し、加圧または加圧加熱することにより、前記第１の基板と前記第２の基板の相対峙する突起電極が、導電性の粒子に接触することにより電気的に接続され、隣接する突起電極間は絶縁されて固定されることを特徴とする基板間の接続方法に関する。更に、本発明は、絶縁性を有する接着剤層が突起電極の高さと同じまたは突起電極の高さより厚く、かつ基板の突起電極部分を除いた形状であり、当該絶縁性接着剤層を異方導電性接着剤層の少なくとも片面に配置してなる多層接着剤を、突起電極を有する第１の基板と、前記突起と相対峙する導電性の突起を有する第２の基板間に配置し、加圧または加圧加熱することにより、前記第１の基板と前記第２の基板の相対峙する導電性の突起が、導電性の粒子に接触することにより電気的に接続され、隣接する突起電極間は絶縁されて固定されることを特徴とする基板間の接続方法に関する。
【０００５】
【発明の実施の形態】
本発明にかかる電極の接続プロセスを、実施例を示した図面を用いて以下に説明する。図１は、接続プロセスを示す模式図である。図１において２は第１の基板に設けられた突起電極であり、これに絶縁性の接着剤層３および異方導電性接着剤層５を配置し、もう一方の基板６の接続用突起電極７面にも同様に絶縁性の接着剤層３を設ける。両基板の導電性の突起が相対峙するように位置合わせを行い加熱、加圧することにより接着剤は流動し複数の導電性の粒子８が、突起電極２と突起電極７の間に接触固定することにより、充分な接触面積が得られる。
また、図２（ａ）において２は第１の基板に設けられた突起電極であり、これに突起電極２の部分を除く形状とした絶縁性の接着剤層３を加圧または加圧加熱により第１の基板１に転写し、さらに全面に異方導電性接着剤層５を転写する。もう一方の第２の基板６にも同様に突起電極７の部分を除く形状とした絶縁性の接着剤層３を転写する。
両基板の突起電極が相対峙するように位置合わせを行い加熱、加圧することにより接着剤は流動し複数の導電性の粒子８が、突起電極２及び７に接触することにより、両基板の電気的接続がはかられる。
図２（ｂ）は別の実施例を示したもので、突起電極部分を除く形状とした絶縁性の接着剤層３を異方導電性の接着剤層５の両面に貼りあわせた多層接着剤層とし、これを突起電極同士を相対峙するように両基板間に配置し、加熱、加圧することにより接続するようにしてもよい。
【０００６】
第１の基板の材料としては、例えばＩＣチップ類のシリコン、ガリウムヒ素等がある。これらＩＣチップは例えば、導電性の突起電極としてＡｌ等の電極上にＣｕ、Ｎｉ、Ａｕ、はんだ等の突起（バンプ）を設けたものであり、これらのバンプの表面にはＳｎ、Ａｕ、はんだ等の表面層を形成することもできる。
酸化シリコン、ホウケイ酸ガラス、チッ化けい素、チッ化アルミニウム、チッ化ホウ素、ポリイミド、テフロン等の絶縁層が突起電極以外を覆っていることが、導電性の粒子とＩＣチップの素子との接触を完全に防止できるので好ましい。第２の基板としては、例えばガラス基板またはセラミック基板、ポリイミド等のフィルム基板やガラスエポキシ基板等の配線板の表面に、突起電極としてＩＴＯ、Ａｌ、Ｎｉ、Ａｕ等の薄膜電極やＣｕ箔や、Ａｇ、Ｎｉ等を含む導電性ペースト類の電極を設けたものであり、これら電極の表面にはＳｎ、Ａｕ、はんだ等の表面層を形成することもできる。また、これらの電極は基板面より凸状であることが導電性の粒子と電極との接触の点で好ましく、電極の高さは後述する導電性の粒子の径よりも大きな２μｍ以上が好ましく、電極表面には凹凸があることから３μｍ以上がより好ましい。電極の高さばらつきは導電性の粒子の粒径よりも小さい方が好ましく、導電性の粒子に均一に圧力を加えるためには、３μｍ以下がより好ましい。
【０００７】
異方導電性接着剤の導電性の粒子は、例えばＡｕ、Ａｇ、Ｃｕやはんだ等の金属の粒子であり、ポリスチレン等の高分子の球状の核材にＮｉ、Ｃｕ、Ａｕ、はんだ等の導電層を設けたものがより好ましい。さらに導電性の粒子の表面にＳｎ、Ａｕ、はんだ等の表面層を形成することもできる。粒径は基板の隣接する電極の最小の間隔よりも小さいことが必要で、電極の高さばらつきがある場合、高さばらつきよりも大きいことが好ましく、３〜５μｍが好ましい。また、加圧または加熱加圧により変形する方がより好ましい。絶縁性の接着剤層は、突起電極の高さと同じか厚くし、導電性の粒子を分散した絶縁性の接着剤の厚みは、導電性の粒子の直径の２倍以内が好ましく、導電性の粒子の直径と同じであることがより好ましい。接着剤は、加圧または加圧加熱時に流動することが必要である。さらに熱または光等で反応するエポキシ、アクリル樹脂等の反応性樹脂が好ましい。
【０００８】
【実施例】
実施例１
以下に、本発明の実施例を図に基づいて説明する。図３は、本発明に関する基板間の接続プロセスを示す模式図である。ＩＣチップとガラス基板の接続に適用した場合を示す。
ＩＣチップ１１（バンプ高さ１５μｍ）の表面にエポキシ樹脂を主体とした絶縁性の接着剤層１３（膜厚２０μｍ）を、加圧加熱（９０℃、１Ｍｐａ）により転写し、ガラス基板１６にエポキシ樹脂を主体とした絶縁性接着剤中に導電性の粒子を分散した異方導電性接着剤層１５（膜厚７μｍ）を加圧加熱（９０℃、１Ｍｐａ）により転写した。次いでＩＣチップ１１のバンプ１２とガラス基板１６の透明電極１７との位置合わせを行い、加圧加熱（１８０℃、１００Ｍｐａ、２０秒）することにより接続した。
ガラス基板側からバンプ上に配置された導電粒子を顕微鏡で観察、粒子数を計測した。
【０００９】
実施例２
図４は、ＩＣチップとガラス基板の接続に適用した場合を示す模式図である。ガラス基板３６にエポキシ樹脂を主体とした絶縁性接着剤中に導電性の粒子を分散した異方導電性接着剤層３５（膜厚７μｍ）を加圧加熱（９０℃、１Ｍｐａ）により転写する。さらにＩＣチップ３１（バンプ高さ１５μｍ）のバンプ３２を除くＩＣチップ内部に配置できるように切断したエポキシ樹脂を主体とした絶縁性の接着剤層３３（膜厚２０μｍ）を、ＩＣチップ３１のバンプ３２の相対峙するガラス基板３６の透明電極３７部分以外に加圧（１Ｍｐａ）転写する。ＩＣチップ３１側に転写してもよい。
ＩＣチップ３１のバンプ３２とガラス基板３６の透明電極３７との位置合わせを行い、加圧加熱（１８０℃、１００Ｍｐａ）し接続した。ガラス基板側からバンプ上に配置された導電粒子を顕微鏡で観察、粒子数を計測した。
なお、本実施例に用いたＩＣチップの突起電極のピッチは８０μｍでバンプ１個あたりの面積は０．０４５ｍｍ^２である。
一方、従来の異方導電性接着剤（膜厚２５μｍ）のみを用い、実施例１と同じ接続条件で接続したものとのバンプ上の粒子数を比較した結果を次に示す。

【００１０】
【発明の効果】
本発明によれば、相対峙する微細な突起電極間の多数の接続を一括して行え、導電性の粒子が接続時の樹脂の流動初期に突起電極に挟まれ微小電極上に数多く配置でき、かつ隣接する電極間の導電性の粒子は、接続時の樹脂の流動により分散されるので、接続抵抗が低く、電気特性に優れた微細電極の電気的接続が行える。
【図面の簡単な説明】
【図１】本発明の接続プロセスを示す模式図である。
【図２】本発明の実施例であるＩＣチップとガラス基板の接続プロセスを示す模式図である。
【図３】本発明の別の実施例であるＩＣチップとガラス基板の接続プロセスを示す模式図である。
【図４】本発明の別の実施例であるＩＣチップとガラス基板の接続プロセスを示す模式図である。
【符号の説明】
１第１の基板２突起電極
３絶縁性接着剤４セパレータ
５異方導電性接着剤６第２の基板
７突起電極８導電性の粒子[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrical connection method between substrates, for example, to a connection between an IC chip having Au bumps and a substrate on which connection terminals are formed.
[0002]
[Prior art]
Conventionally, as a connection method when connection terminals are formed at a fine pitch facing each other, such as a connection of an integrated circuit to a wiring board, a connection between a display element and a wiring board, etc. By providing an anisotropic conductive connecting member layer composed of conductive particles such as metal particles and an adhesive component between terminals, and by applying pressure or heating / pressing means, electrical connection between circuits can be performed simultaneously between adjacent circuits. A method has been used in which insulation is imparted and opposing circuits are bonded and fixed.
However, in these methods, since the anisotropic conductive connection member layer in which the conductive particles are dispersed is connected while flowing, the conductive particles disposed between the opposing electrodes flow together with the adhesive. While being sandwiched between the electrodes. The conduction between the electrodes is mainly obtained by a plurality of conductive materials, and a plurality of conductive particle materials are distributed on the electrodes in the connection of the fine pitch and minute electrodes, and the insulation between the adjacent electrodes is maintained. Things are getting harder.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and has been accomplished as a result of studies to achieve connection of finer electrodes. The present invention provides a method of connecting fine electrodes with improved electrical characteristics of a connection portion. It is intended for that purpose.
[0004]
[Means for Solving the Problems]
According to the present invention, an insulating adhesive is applied to at least one of the first substrate having the protruding electrodes and the second substrate having the protruding electrodes opposed to the protruding electrodes at the same height as the height of the protruding electrodes. Alternatively, an anisotropic conductive adhesive in which conductive particles are dispersed in an adhesive having an insulating property is disposed between the first substrate and the second substrate while being disposed thicker than the height of the protruding electrode. By pressurizing or heating, the opposing protruding electrodes of the first substrate and the second substrate are electrically connected to each other by contacting conductive particles. The present invention relates to a method for connecting substrates, which is insulated and fixed. Furthermore, the present invention, the adhesive layer having an insulating property is greater than the height of the same or protruding electrodes and the height of the bump electrode, and a shape excluding the protruding electrode portion of the substrate, anisotropic said insulating adhesive layer a conductive adhesive multilayer adhesive formed by arranging at least one side of the layer, disposed between the second substrate having a first substrate having a protruding electrode, a conductive protrusion of the projection and faced each other, pressurizing When pressure or pressure is applied, the opposing conductive protrusions of the first substrate and the second substrate are electrically connected to each other by contacting conductive particles, and are electrically connected between adjacent protrusion electrodes. The present invention relates to a method for connecting substrates, which is insulated and fixed.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
An electrode connection process according to the present invention will be described below with reference to the drawings showing examples. FIG. 1 is a schematic diagram showing the connection process. In FIG. 1, reference numeral 2 denotes a projection electrode provided on a first substrate, on which an insulating adhesive layer 3 and an anisotropic conductive adhesive layer 5 are arranged, and a connection projection electrode of the other substrate 6. Similarly, an insulating adhesive layer 3 is provided on the seven surfaces. By positioning and heating and applying pressure so that the conductive protrusions of both substrates face each other, the adhesive flows and a plurality of conductive particles 8 are fixed between the protrusion electrodes 2 and the protrusion electrodes 7. Thereby, a sufficient contact area can be obtained.
In FIG. 2A, reference numeral 2 denotes a projecting electrode provided on the first substrate, on which an insulating adhesive layer 3 having a shape excluding the projecting electrode 2 is pressed or heated under pressure. The image is transferred to the first substrate 1, and the anisotropic conductive adhesive layer 5 is further transferred to the entire surface. Similarly, the insulating adhesive layer 3 having a shape excluding the protruding electrode 7 is transferred to the other second substrate 6.
By positioning and heating and applying pressure so that the protruding electrodes of both substrates face each other, the adhesive flows and a plurality of conductive particles 8 come into contact with the protruding

electrodes

2 and 7, so that the electric potential of both substrates is reduced. Connection is established.
FIG. 2B shows another embodiment, in which a multi-layer adhesive in which an insulating adhesive layer 3 having a shape excluding a protruding electrode portion is bonded to both surfaces of an anisotropic conductive adhesive layer 5. A layer may be arranged between the two substrates so that the protruding electrodes face each other, and the layers may be connected by heating and pressing.
[0006]
Examples of the material for the first substrate include silicon and gallium arsenide of IC chips. These IC chips are, for example, provided with protrusions (bumps) of Cu, Ni, Au, solder, etc. on electrodes of Al or the like as conductive protrusion electrodes, and Sn, Au, solder on the surface of these bumps. Etc. can be formed.
The contact between the conductive particles and the IC chip element is that the insulating layer of silicon oxide, borosilicate glass, silicon nitride, aluminum nitride, boron nitride, polyimide, Teflon, etc. covers other than the protruding electrodes. This is preferable since it is possible to completely prevent As the second substrate, for example, a glass substrate or a ceramic substrate, a thin film electrode such as ITO, Al, Ni, Au or the like, a Cu foil, An electrode of a conductive paste containing Ag, Ni, or the like is provided, and a surface layer of Sn, Au, solder, or the like can be formed on the surface of these electrodes. Further, these electrodes are preferably convex from the substrate surface in terms of contact between the conductive particles and the electrodes, and the height of the electrodes is preferably 2 μm or more, which is larger than the diameter of the conductive particles described below, Since the electrode surface has irregularities, it is more preferably 3 μm or more. The height variation of the electrode is preferably smaller than the particle size of the conductive particles, and more preferably 3 μm or less in order to uniformly apply pressure to the conductive particles.
[0007]
The conductive particles of the anisotropic conductive adhesive are, for example, metal particles such as Au, Ag, Cu, and solder, and the conductive particles such as Ni, Cu, Au, and solder are attached to a polymer spherical core material such as polystyrene. Those having a layer are more preferred. Further, a surface layer of Sn, Au, solder or the like can be formed on the surface of the conductive particles. The particle size needs to be smaller than the minimum distance between adjacent electrodes on the substrate, and when there is a height variation of the electrodes, it is preferably larger than the height variation, and more preferably 3 to 5 μm. Moreover, it is more preferable to deform by pressurization or heat and pressure. Insulating adhesive layer is either equal to the height of the bump electrode thickness comb, the thickness of the conductive insulating adhesive in which particles are dispersed, the conductive is preferably within 2 times the diameter of the particles, the conductive More preferably, it is the same as the diameter of the particles. The adhesive needs to flow when pressed or heated under pressure. Further, a reactive resin such as an epoxy resin or an acrylic resin which reacts by heat or light is preferable.
[0008]
【Example】
Example 1
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a schematic diagram showing a connection process between substrates according to the present invention. This shows a case where the present invention is applied to connection between an IC chip and a glass substrate.
An insulating adhesive layer 13 (film thickness: 20 μm) mainly composed of epoxy resin is transferred to the surface of the IC chip 11 (bump height: 15 μm) by pressurizing and heating (90 ° C., 1 Mpa), and epoxy-coated on a glass substrate 16. An anisotropic conductive adhesive layer 15 (7 μm thick) in which conductive particles were dispersed in a resin-based insulating adhesive was transferred by pressure and heat (90 ° C., 1 Mpa). Next, the bump 12 of the IC chip 11 and the transparent electrode 17 of the glass substrate 16 were aligned, and connected by applying pressure and heating (180 ° C., 100 Mpa, 20 seconds).
The conductive particles placed on the bumps from the glass substrate side were observed under a microscope, and the number of particles was counted.
[0009]
Example 2
FIG. 4 is a schematic diagram showing a case where the present invention is applied to a connection between an IC chip and a glass substrate. An anisotropic conductive adhesive layer 35 (7 μm thick) in which conductive particles are dispersed in an insulating adhesive mainly composed of an epoxy resin is transferred to a glass substrate 36 by pressurizing and heating (90 ° C., 1 Mpa). Further, an insulating adhesive layer 33 (film thickness: 20 μm) mainly made of epoxy resin cut so as to be arranged inside the IC chip except for the bump 32 of the IC chip 31 (bump height: 15 μm) is attached to the bump of the IC chip 31. Pressure (1 Mpa) transfer is performed to portions other than the transparent electrode 37 portion of the glass substrate 36 facing 32. It may be transferred to the IC chip 31 side.
The bumps 32 of the IC chip 31 were aligned with the transparent electrodes 37 of the glass substrate 36, and were connected by heating under pressure (180 ° C., 100 MPa). The conductive particles placed on the bumps from the glass substrate side were observed under a microscope, and the number of particles was counted.
The pitch of the projecting electrodes of the IC chip used in this example was 80 μm, and the area per bump was 0.045 mm ² .
On the other hand, the results of comparing the number of particles on the bumps with those connected under the same connection conditions as in Example 1 using only the conventional anisotropic conductive adhesive (film thickness 25 μm) are shown below.

[0010]
【The invention's effect】
According to the present invention, a large number of connections between opposing fine projection electrodes can be collectively performed, and a large number of conductive particles can be arranged on the microelectrodes sandwiched between the projection electrodes in the initial flow of the resin at the time of connection, In addition, since the conductive particles between the adjacent electrodes are dispersed by the flow of the resin at the time of connection, a fine electrode having low connection resistance and excellent electrical characteristics can be electrically connected.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a connection process of the present invention.
FIG. 2 is a schematic view illustrating a process of connecting an IC chip and a glass substrate according to an embodiment of the present invention.
FIG. 3 is a schematic view showing a process of connecting an IC chip and a glass substrate according to another embodiment of the present invention.
FIG. 4 is a schematic view showing a process of connecting an IC chip and a glass substrate according to another embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 first substrate 2 projecting electrode 3 insulating adhesive 4 separator 5 anisotropic conductive adhesive 6 second substrate 7 projecting electrode 8 conductive particles

Claims

A first substrate having a protruding electrode and an insulating adhesive layer on at least one protruding electrode surface on a second substrate having a protruding electrode opposed to the protruding electrode have the same height as the height of the protruding electrode or the protruding electrode. And an anisotropic conductive adhesive in which conductive particles are dispersed in an adhesive having an insulating property between the first substrate and the second substrate. By pressurizing and heating, the opposing projecting electrodes of the first substrate and the second substrate are electrically connected by contacting conductive particles, and the adjacent projecting electrodes are insulated. A connection method between substrates, which is fixed.

Adhesive layer having an insulating property according to claim 1 is thicker than the height of the same or protruding electrodes and the height of the bump electrode, and a shape excluding the protruding electrode portion of the substrate, anisotropic said insulating adhesive layer a conductive adhesive multilayer adhesive formed by arranging at least one side of the layer, disposed between the second substrate having a first substrate having a protruding electrode, a conductive protrusion of the projection and faced each other, pressurizing When pressure or pressure is applied, the opposing conductive protrusions of the first substrate and the second substrate are electrically connected to each other by contacting conductive particles, and are electrically connected between adjacent protrusion electrodes. connection between the substrates, characterized in that is fixed is insulated.