JP4466189B2 - Connecting material - Google Patents

Description

  The present invention relates to a liquid or paste connection material for connecting various electronic components such as an IC chip to a flexible or rigid wiring board.

  Conventionally, a chip-on-board method (COB method) and a chip-on-film method (COF method) have been widely used as packaging methods for flip-chip mounting electronic components such as IC chips on a wiring board. It was common to use anisotropic conductive adhesive film for anisotropic conductive connection, but instead of anisotropic conductive adhesive film for the purpose of reducing material and equipment costs and shortening tact time. Connection materials such as liquid or paste-like anisotropic conductive adhesives and non-conductive adhesives are used.

  As a conventional general liquid or paste-like connection material, a thermosetting component composed of a thermosetting epoxy resin and a latent curing agent is added to a non-conductive material for adjusting the linear expansion coefficient and moisture absorption rate of the connection material. A conductive agent, a coupling agent for creating a good bonding state between a thermosetting component and a non-conductive filler, and conductive particles for anisotropic conductive connection, if necessary, uniformly dispersed Is used (Patent Document 1).

  By the way, recently, higher connection reliability has been demanded for flip chip mounting bodies formed by a COF method or a COB method using a liquid or paste-like connection material. In particular, in the case of the COB method, moisture absorption reflow resistance of level 3 or level 2A of JEDEC (Joint Electron Device Engineering Council) standard is required.

JP2000-80341

  However, in the case of a liquid or paste-like connection material, the range of the amount of non-conductive filler is narrower than that of a resin composition for forming an anisotropic conductive adhesive film, and a high molecular weight or high viscosity resin component However, there is a problem that it is difficult to connect with high reliability because there is a problem that the degree of freedom of blending is small. Moreover, when a JEDEC level 2A moisture absorption reflow test is performed, there is a problem that, for example, floating occurs between the IC chip and the connection material.

  For connection materials in liquid or paste form, it has good storage characteristics such that there is little change in viscosity during storage at room temperature, and good PCT resistance that connection resistance does not increase by a PCT (pressure cooker test) test. It is also required to prepare.

  The present invention is intended to solve the above-described problems of the prior art, and enables connection with high reliability to a liquid or paste-like connection material, excellent storage characteristics, and JEDEC level 2A. An object is to provide good moisture absorption reflow resistance that does not cause floating even when a moisture absorption reflow test is performed.

  The inventors have (1) the above-mentioned problems in the liquid or paste-like connecting material are not only the adhesion between the IC chip or the wiring board and the cured thermosetting component in the connecting material, but most of the conventional Depends largely on the quality of adhesion between the non-conductive filler surface and the cured thermosetting component that has not been considered, and (2) the non-conductive filler surface and the cured thermosetting component. If the adhesion between them is not sufficient, cracks are likely to occur at their interfaces during the moisture absorption reflow test, and as a result, the connecting material is likely to absorb moisture, and (3) solve these problems. For this purpose, the present invention has been completed by finding that two kinds of silane coupling agents having different reactivities to the non-conductive filler may be used in a specific amount range in the connection material.

  That is, the present invention provides a connecting material containing a thermosetting component, a non-conductive filler, and a silane coupling agent, wherein the silane coupling agent comprises a first silane coupling agent and a second silane coupling agent. And the reactivity of the first silane coupling agent to the non-conductive filler is higher than the reactivity of the second silane coupling agent to the non-conductive filler, and the content of the first silane coupling agent Is 0.15-1.85 parts by weight with respect to 100 parts by weight of the non-conductive filler, and the content of the second silane coupling agent is 0.80-12.12 with respect to 100 parts by weight of the non-conductive filler. There is provided a connecting material characterized in that it is 00 parts by weight.

  The connection material of the present invention can be connected with high reliability while being in a liquid or paste form, and also has excellent storage characteristics and does not cause floating even when a JEDEC level 2A moisture absorption reflow test is performed. And good moisture absorption reflow resistance.

  Hereinafter, the present invention will be described in detail.

  The present invention is a connecting material containing a thermosetting component, a non-conductive filler, and a silane coupling agent. The silane coupling agent is a first material that exhibits relatively high reactivity with respect to the non-conductive filler. A silane coupling agent and a second silane coupling agent exhibiting relatively low reactivity are used in combination. Here, critical surface tension is mentioned as an index of the reactivity of the silane coupling agent with respect to the non-conductive filler. When the critical surface tension for the same substrate (for example, soda glass substrate) is compared, the smaller the critical surface tension, the higher the reactivity.

  In the present invention, the reason why two types of silane coupling agents having different reactivity are used in combination is as follows.

  That is, when the first silane coupling agent having a relatively high reactivity with respect to the conductive filler is used alone as the silane coupling agent, the reactivity with the nonconductive filler is high, but it should be connected. The adhesion between the wiring board or IC chip and the thermosetting component after curing is insufficient, the PCT resistance of the connecting material is lowered, and the second is relatively low reactivity with respect to the non-conductive filler. When the silane coupling agent of No. 2 is used alone as a silane coupling agent, the adhesion between the wiring board or IC chip to be connected and the thermosetting component after curing can be achieved without increasing the viscosity of the connecting material. Although it can be improved, the adhesion between the non-conductive filler and the thermosetting component after curing becomes insufficient, and the moisture absorption reflow resistance is lowered. Therefore, in the present invention, the combination of the first silane coupling agent and the second coupling agent, which have different reactivity with respect to the non-conductive filler, is used together with the thermosetting component after curing and the non-conductive. Balance between the adhesiveness between the adhesive filler and the adhesiveness between the cured thermosetting component and the wiring board or IC chip to be connected.

  If the content of the first silane coupling agent in the connecting material is too small, cracks are generated at the boundary between the non-conductive filler and the thermosetting component after curing, and the conduction reliability is lowered. An unreacted first silane coupling agent remains in the connecting material with respect to the non-conductive filler, and this reacts with a functional group (for example, epoxy group) of the thermosetting component to increase the viscosity of the connecting material itself. As a result, the crimping operation becomes difficult, so the amount is 0.15 to 1.85 parts by weight, preferably 0.2 to 1.7 parts by weight with respect to 100 parts by weight of the non-conductive filler.

  In addition, if the content of the second silane coupling agent is too small, the adhesion between the wiring substrate or IC chip to be connected and the thermosetting component after curing becomes insufficient, resulting in moisture absorption reflow resistance. If the amount is too high, the unreacted second silane coupling agent remains in the connecting material with respect to the non-conductive filler, causing voids and open after the PCT test. The amount is 0.80 to 12.00 parts by weight, preferably 1.00 to 11.00 parts by weight, based on 100 parts by weight of the filler.

  Specific examples of silane coupling agents that can be used in the present invention are shown in Table 1 below.

In the present invention, two different types are selected from these, and the higher reactivity is positioned as the first silane coupling agent, and the lower reactivity is positioned as the second silane coupling agent. Here, the difference in critical surface tension between the first silane coupling agent and the second silane coupling agent is preferably 3 dyne / cm or more and 10 dyne / cm or less.

  Further, the content weight ratio of the first silane coupling agent and the second coupling agent is such that the PCT resistance (if the second silane coupling agent is too small relative to the first silane coupling agent ( The pressure cooker test resistance) is low, and if it is too much, the viscosity increases or hardens, so that it is preferably 1: 0.85 to 1: 0.05, more preferably 1: 0.75 to 1: 0.07.

  In the present invention, the non-conductive filler is for adjusting the linear expansion coefficient and moisture absorption rate of the connecting material. Examples of such a non-conductive filler include silica fine particles and titanium oxide particles having a particle size of about 0.1 to 5 μm. Among these, silica fine particles are preferable from the viewpoint of cost.

  As the thermosetting component used in the present invention, the thermosetting component used in the conventional anisotropic conductive adhesive paste and non-conductive adhesive paste can be used. Among these, a thermosetting component containing a polymerizable epoxy compound and a latent curing agent can be preferably used from the viewpoint of conduction reliability and connection reliability.

  As such a polymerizable epoxy compound, an epoxy monomer or oligomer having a molecular weight (weight average molecular weight) of 10,000 or less can be preferably exemplified. For example, glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenol novolac, cresol novolac; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, polypropylene glycol; phthalic acid, isophthalic acid, tetrahydrophthalic acid, etc. Mention may be made of epoxy monomers such as glycidyl esters of carboxylic acids and their oligomers or alicyclic epoxides. Among these, bisphenol A glycidyl ether monomer or oligomer can be preferably used. Specifically, Epicoat 828 (molecular weight 380), Epicoat 834 (molecular weight 470), Epicoat 1001 (molecular weight 900), Epicoat 1002 (molecular weight 1060), Epicoat 1055 (molecular weight 1350), Epicoat 1007 (molecular weight) manufactured by Yuka Shell Co., Ltd. 2900) or the like. These may be used alone or in combination of two or more.

  As the latent curing agent, those used in known thermosetting epoxy adhesives can be used, for example, imidazole (for example, HX3748, Asahi Kasei Chemicals), amine (PN-23, Ajinomoto Co., Inc.). ), Latent curing agents of dicyandiamide type (DCMV 99, ACI Japan Limited) and the like can be used.

  The amount of the latent curing agent used is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the polymerizable epoxy compound.

  In addition to the components described above, a crosslinking agent, various rubber components, fillers, leveling agents, viscosity modifiers, antioxidants, and the like can be appropriately blended with the connection material of the present invention as necessary. In particular, the addition of conductive particles for anisotropic conductive connection is preferable because the connection material can be used as a liquid or paste-like anisotropic conductive adhesive. Examples of such conductive particles include conventionally known conductive particles, for example, metal particles such as nickel and gold, composite particles in which the surface of a thermoplastic resin core is coated with the above-mentioned metal, and the surfaces of metal particles and composite particles are insulated. Particles coated with a conductive resin thin film can be used.

  In the connection material of the present invention, a thermosetting component, a non-conductive filler, a silane coupling agent and other components added as needed are uniformly mixed with a known stirring device after vacuum defoaming treatment. Can be manufactured.

  The connection material of the present invention is used in a liquid or paste form, although it varies depending on the type and quantity ratio of raw materials used.

  When using the connection material of the present invention, for example, the connection material is applied to the connection terminal region of the wiring board by a known coating device, and various electronic components such as an IC chip are aligned and then heat-bonded with a heat bonder. .

  Hereinafter, the present invention will be specifically described by way of examples.

Examples 1-6 and Comparative Examples 1-4
Each component of the recipes shown in Tables 2 and 3 was vacuum degassed at 40 ° C. for 60 minutes, and then uniformly mixed with a planetary stirrer (Nentaro, THINKY) to prepare a connection material. did. The storage stability of the obtained connection material was evaluated as described below.

  The content of the first silane coupling agent with respect to 100 parts by weight of the non-conductive filler [(A) wtp / 100% by weight of filler] and the content of the second silane coupling agent with respect to 100 parts by weight of the non-conductive filler [(B) wtp / filler 100 wtp] are shown in Tables 2 and 3.

(Storage stability)
The connection material is allowed to stand at room temperature for one week, and the case where the change in viscosity relative to the initial viscosity is less than ± 20% is evaluated as “good”. Some cases were evaluated as “bad” and described as “x” in Tables 2 and 3.

  Next, about 2 to 5 mg of the obtained connection material is applied to a COB substrate (FR5, 150 μm pitch, Sony Chemical TEG substrate) with a dispenser, and Au plating bumps (size: 60 μm square) are applied to the coating film. IC chip (size: 6.3 mm square, 0.4 mm thickness) formed with 0.2 μm height and bump pitch: 100 μm is aligned, and heat-bonded with a heat bonder on a pedestal heated to 80 ° C. ( The heating temperature was 230 ° C., the heating time was 5 seconds, and the pressure was 0.59 N / bump) to prepare a COB connector.

  The obtained COB connector was evaluated for moisture absorption reflow resistance and PCT resistance as shown below. The obtained results are shown in Tables 2 and 3.

(Moisture absorption reflow resistance)
The obtained COB connector was subjected to moisture absorption reflow treatment under the condition of JEDEC level 2A (3 hours of reflow treatment at a maximum temperature of 245 ° C after being left at 85 ° C / 85% RH for 24 hours). After leaving in an atmosphere of 100 ° C., 100% RH, 202.6 kPa for 100 hours, the connection resistance value was measured by the four-terminal method. The case where the maximum resistance value is 200 mΩ or less is evaluated as “good”, “O” is described in Table 2 and Table 3, the case where it exceeds 200 mΩ is evaluated as “Poor”, and in Table 2 and Table 3. It was described as “X”.

(PCT resistance)
The obtained COB connector was left in an atmosphere of 121 ° C., 100% RH, 202.6 kPa for 300 hours, and then the connection resistance value was measured by a four-terminal method. The case where the maximum resistance value is 200 mΩ or less is evaluated as “good”, “O” is described in Table 2 and Table 3, the case where it exceeds 200 mΩ is evaluated as “Poor”, and in Table 2 and Table 3. It was described as “X”.

表２及び表３注
*1: HP3748、旭化成ケミカルズ社
*2: EP828、油化シェルエポキシ社
*3: HX3748、旭化成ケミカルズ社
*4: シリカ微粒子、DF5VLD、龍森社
*5: アミノ変性タイプ、KBM603、信越化学社
*6: 未変性タイプ、KBM403、信越化学社
*7: 粒径3.5μmのベンゾグアナミン樹脂粒子にNi/Auメッキを施した導電粒子

Table 2 and Table 3 Note
* 1: HP3748, Asahi Kasei Chemicals Corporation
* 2: EP828, Yuka Shell Epoxy
* 3: HX3748, Asahi Kasei Chemicals Corporation
* 4: Silica fine particles, DF5VLD, Tatsumorisha
* 5: Amino-modified type, KBM603, Shin-Etsu Chemical
* 6: Unmodified type, KBM403, Shin-Etsu Chemical
* 7: Conductive particles with Ni / Au plating on benzoguanamine resin particles with a particle size of 3.5μm

  As shown in Tables 2 and 3, from the results of Comparative Examples 3 and 4, the content of the first silane coupling agent is 0.125 parts by weight with respect to 100 parts by weight of the non-conductive filler. It can be seen that the amount is too small and the moisture absorption reflow resistance is insufficient, and the amount of 2 parts by weight is too large and lacks storage stability. On the other hand, from the results of Examples 4 and 5, if the content of the first silane coupling agent is 0.25 parts by weight to 1.75 parts by weight with respect to 100 parts by weight of the non-conductive filler, good moisture absorption resistance It can be seen that reflowability and storage stability were obtained. Therefore, it is understood that the content of the first silane coupling agent is 0.15 to 1.85 parts by weight with respect to 100 parts by weight of the non-conductive filler.

  In addition, from the results of Comparative Examples 1 and 2, the content of the second silane coupling agent is too small to be 0.75 parts by weight with respect to 100 parts by weight of the non-conductive filler, and the moisture absorption reflow resistance is insufficient. It can be seen that the amount of 12.5 parts by weight is too large and lacks PCT resistance. On the other hand, from the results of Examples 2 and 3, when the content of the second silane coupling agent is 1.00 to 11.25 parts by weight with respect to 100 parts by weight of the non-conductive filler, good PCT resistance It turns out that sex was obtained. Therefore, it can be seen that the content of the second silane coupling agent is appropriately 0.80 to 12.00 parts by weight with respect to 100 parts by weight of the non-conductive filler.

The connection material of the present invention can be connected with high reliability while being in a liquid or paste form, and also has excellent storage characteristics and does not cause floating even when a JEDEC level 2A moisture absorption reflow test is performed. And good moisture absorption reflow resistance. Therefore, the connection material of the present invention is useful as a liquid or paste connection material for connecting various electronic components such as an IC chip to a flexible or rigid wiring board.

Claims (5)

In a connection material containing a thermosetting component, a non-conductive filler, and a silane coupling agent, the silane coupling agent includes a first silane coupling agent and a second silane coupling agent, The reactivity of the silane coupling agent to the non-conductive filler is higher than the reactivity of the second silane coupling agent to the non-conductive filler, and the first silane coupling agent and the second silane coupling agent are The difference in critical surface tension of 3 to 10 dyne / cm, the content of the first silane coupling agent is 0.15 to 1.85 parts by weight with respect to 100 parts by weight of the non-conductive filler, The content of the silane coupling agent is 0.80 to 12.00 parts by weight with respect to 100 parts by weight of the non-conductive filler.   The connecting material according to claim 1, wherein a content weight ratio of the first silane coupling agent and the second coupling agent is 4: 3 to 15: 1.   The connection material according to claim 1, wherein the nonconductive filler is silica fine particles.   The connection material according to claim 1, wherein the thermosetting component contains a thermosetting epoxy resin and a latent curing agent. Furthermore, the connection material in any one of Claims 1-4 containing the electroconductive particle for anisotropic conductive connections.