Search

EP-4084020-B1 - CONNECTION STRUCTURE AND MANUFUCTURING METHOD THEREFOR

EP4084020B1EP 4084020 B1EP4084020 B1EP 4084020B1EP-4084020-B1

Inventors

  • AKAI, KUNIHIKO
  • MIYAJI, MASAYUKI
  • KAKEHATA, JUNICHI
  • EJIRI, YOSHINORI
  • MORIYA, TOSHIMITSU

Dates

Publication Date
20260506
Application Date
20201204

Claims (6)

  1. A connection structure comprising: a first circuit member (30) having a plurality of first electrodes (32); a second circuit member (40) having a plurality of second electrodes (42); and an intermediate layer (80) having a plurality of bonding portions (70) electrically connecting the first electrodes and the second electrodes, wherein at least one of the first electrode and the second electrode that are connected by the bonding portion is a gold electrode, 90% or more of the plurality of bonding portions include a first region (71) containing a tin-gold alloy and connecting the first electrode and the second electrode and a second region (72) containing bismuth and being in contact with the first region, and characterised in that the first region has a columnar structure connecting the first electrode and the second electrode, and the second region has an annular structure surrounding the first region.
  2. The connection structure according to claim 1, wherein the intermediate layer further has an insulating resin layer (55) sealing a space between the first circuit member and the second circuit member.
  3. A method for manufacturing a connection structure, the method comprising: a preparing step of preparing a first circuit member (30) having a plurality of first electrodes (32), a second circuit member (40) having a plurality of second electrodes (42), and an anisotropically conductive film (10); a disposing step of disposing the first circuit member, the second circuit member, and the anisotropically conductive film such that a surface of the first circuit member on which the first electrodes are provided and a surface of the second circuit member on which the second electrodes are provided to face each other with the anisotropically conductive film interposed therebetween, to obtain a laminate in which the first circuit member, the anisotropically conductive film, and the second circuit member are laminated in this order; and a connecting step of electrically connecting the first electrodes and the second electrodes via the bonding portions (70) by heating the laminate in a state of being pressed in a thickness direction, wherein at least one of the first electrode and the second electrode is a gold electrode, the anisotropically conductive film includes an insulating film (2) constituted by an insulating resin composition and a plurality of solder particles (1) disposed in the insulating film, the solder particle contains a tin-bismuth alloy, and the average particle diameter of the solder particle is 1 µm to 30 µm, and the C.V. value of the solder particle is 20% or less, in a longitudinal section of the anisotropically conductive film, the solder particle is disposed to be arranged in a transverse direction in a state of being spaced apart from the solder particle adjacent thereto, 90% or more of the plurality of bonding portions to be formed in the connecting step include a first region (71) containing a tin-gold alloy and connecting the first electrode and the second electrode and a second region (72) containing bismuth and being in contact with the first region, and characterised in that the first region has a columnar structure connecting the first electrode and the second electrode, and the second region has an annular structure surrounding the first region.
  4. The manufacturing method according to claim 3, wherein the solder particle is a solder particle manufactured by a method including: a solder fine particle preparing step of preparing a base substrate (60) having a plurality of recesses (62) and solder fine particles (111) containing a tin-bismuth alloy; an accommodating step of accommodating at least some of the solder fine particles in the recess; and a fusing step of fusing the solder fine particles accommodated in the recess to form a solder particle inside the recess.
  5. The manufacturing method according to claim 4, wherein the C.V. value of the solder fine particle to be prepared in the solder fine particle preparing step exceeds 20.
  6. The manufacturing method according to any one of claims 3 to 5, wherein the anisotropically conductive film is an anisotropically conductive film manufactured by a method including: a transferring step of bringing an insulating resin composition into contact with an opening side of a recess of a base substrate having a plurality of recesses in which the solder particles are accommodated in the recesses, to obtain a first resin layer (2b) to which the solder particles are transferred; and a laminating step of forming a second resin layer (2d) constituted by an insulating resin composition on a surface (2c) of the first resin layer on a side to which the solder particles are transferred, to obtain an anisotropically conductive film.

Description

Technical Field The present invention relates to a connection structure and a method for manufacturing a connection structure. Background Art A semiconductor chip to be mounted on an electronic device is mounted on a circuit board by wire bonding, ball grid array (BGA) connection using solder balls, or the like, is then sealed with an insulating resin material, and is used as a function integrated body called a semiconductor package. In particular, the BGA connection can narrow a pitch between electrodes, and thus has contributed to a decrease in size of a semiconductor package (Patent Literature 1). In recent years, for small-sized and high-performance products such as smartphones and tablets, height-reducing, thinning, and increasing performance of a semiconductor package has proceeded, and increasing of the number of electrodes to be connected and narrowing of a pitch between electrodes have proceeded. In a primary connection side of a semiconductor package, in order to realize narrow pitch connection of 100 µm or less, a soldered Cu pillar structure has been used in which solder is laminated at a tip of a copper pillar (Patent Literature 2). Furthermore, from the viewpoint of environmental performance, lead-free solder with silver or copper added to tin had been used since 2000s, and mounting has been performed at a reflow temperature of about 260°C. However, in a semiconductor package that is a composite body of a metal, glass, a resin, and the like, a problem arises in that a stress is applied to a mounting portion (soldering portion) from a difference in thermal expansion coefficient between respective materials due to thermal history by reflow at 260°C, resulting in breakage. Furthermore, in the case of reflow at 260°C, a problem also arises in that solder and a metal material of an electrode are alloyed to generate an alloy layer that promotes breakage. Furthermore, a problem arises in that reflow at 260°C is required for tin-silver-based solder, and thus a less expensive resin material cannot be applied. Patent Literature 3 discloses a mounting method using a low-temperature solder that uses tin and bismuth and has a melting point of 200°C or lower. However, the tin-bismuth solder has a problem in that a solder bonding portion is easily broken by an impact from the outside since bismuth is brittle. In Patent Literature 4, an attempt has been conducted in which the brittleness of a bonding portion is improved by adding a trace amount of a metal to tin-bismuth solder. Meanwhile, as a method of collectively and electrically connecting a large number of electrodes, anisotropically conductive materials such as an anisotropically conductive film and an anisotropically conductive paste have been hitherto used. The anisotropically conductive materials have been used for collectively mounting a large number of wirings such as mounting of a control IC on a display or connection and mounting of tab wires, and make it possible connection of narrow pitches below 30 µm in recent years. As conductive particles to be blended with these anisotropically conductive materials, it has been hitherto studied to use solder particles. For example, Patent Literature 5 describes a conductive paste that contains a thermosetting component and a plurality of solder particles subjected to a specific surface treatment. Patent literature 6 and 7 disclose the preambles of the independent claims. Citation List Patent Literature Patent Literature 1: Japanese Unexamined Patent Publication No. 2003-7894Patent Literature 2: Japanese Unexamined Patent Publication No. 2015-106654Patent Literature 3: Japanese Unexamined Patent Publication No. 2014-84395Patent Literature 4: International Publication WO 2014061085Patent Literature 5: Japanese Unexamined Patent Publication No. 2016-76494Patent Literature 6: JP2019029135Patent Literature 7: US2013000964 Summary of Invention Technical Problem As described above, in recent years, with a decrease in connection temperature corresponding to diversity of circuit members and high definition of circuit members, a decrease in size and thickness of connection points has proceeded, and thus it becomes difficult to secure the conduction reliability of a connection structure. The present invention has been made in view of the above circumstances, and an object thereof is to provide a connection structure excellent in conduction reliability and insulation reliability and a manufacturing method therefor. Solution to Problem An aspect of the present invention relates to a connection structure including: a first circuit member having a plurality of first electrodes; a second circuit member having a plurality of second electrodes; and an intermediate layer having a plurality of bonding portions electrically connecting the first electrodes and the second electrodes, in which at least one of the first electrode and the second electrode that are connected by the bonding portion is a gold electrode, and 90% or mor