JP2012134383A - Method for connection of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel method which allows electrical connection between an electronic component and a substrate to be made with ease and good yield.SOLUTION: The method for electrically connecting an electronic component having a second electrode for connection with a substrate having a first electrode for connection through the first and second electrodes comprises: a step for putting a conductive paste on the first electrode of the substrate; a step for putting a thermosetting resin sheet in an area of the substrate where the first electrode is not formed; and a step for mounting the electronic component on the substrate so that the second electrode is brought into contact with the first electrode of the substrate, and heating the substrate with the electronic component to a temperature of 80-150°C under a pressure of 0.1 Pa or below to harden by heat the conductive paste and the thermosetting resin sheet concurrently, thereby electrically connecting the electronic component with substrate.

Description

  The present invention relates to a method for connecting electronic components.

  In the die attach process in the assembly process of an electronic component, after the liquid adhesive is applied to the substrate and the electronic component is mounted, the liquid adhesive is heated and cured to connect the electronic component to the substrate. However, in the assembly of electronic components by the die attach process, liquid adhesive adheres to the surface of the electronic component or the pad of the substrate, or the substrate electrode portion and the pad of the electronic component are separated by oozing into the electrode portion of the substrate. There has been a problem that the reliability of electrical connection between the electronic component and the substrate is inferior due to fluctuations in the area and width of the bonding region of the conductive paste for connection.

  In view of such problems, for example, when connecting an interposer on which a semiconductor chip is mounted and a substrate, first, a thermosetting resin sheet is interposed between the interposer and the substrate, and this thermosetting resin sheet After applying a heat of about 150 ° C. to melt and then curing, mechanically connecting the interposer and the substrate, the conductive bump formed on the lower portion of the interposer is heated to melt at about 230 ° C. A method of electrically connecting a substrate and the like has been proposed (Patent Document 1).

  First, after electrically connecting the conductive bumps of the semiconductor element and the electrode part of the substrate, the epoxy resin is filled between the semiconductor element and the substrate, and the epoxy resin is cured by heating to a certain temperature. Thus, a method of mechanically connecting the semiconductor element and the substrate has also been proposed (Patent Document 2).

  However, the above-described technology requires at least two heating steps, and further includes a pressurization step as necessary. This causes a problem of high costs accompanying an increase in the number of steps, and further pressurization. In the case of including a process, if the electronic component is fragile, it is not preferable because damage or the like occurs.

  On the other hand, before mounting a semiconductor chip, a paste to which conductive particles are added using an epoxy resin as a base resin is applied or a conductive film is placed on a semiconductor element mounting region of a substrate to be mounted in advance, and then the paste or the conductive film A method has been proposed in which a semiconductor chip and a substrate are mechanically and electrically connected at the same time by mounting the semiconductor chip via a pin (Patent Document 3).

  However, in the case of this method, conductive particles and the like are dispersed in addition to the electrical connection portion, so that a portion where electrical insulation must be taken between the semiconductor chip and the substrate is conducted, or the conductive particles However, since the conductive particles and the like are dispersed in addition to the electrical connection portion, there has been a problem that the cost is increased. In addition, since the pressurizing step is an essential step, as described above, when the semiconductor chip is fragile, there is a problem that the semiconductor chip is damaged.

Patent 2002-343828 JP-A-9-181122 JP 2001-326245 A

  An object of the present invention is to provide a novel method capable of easily and mechanically connecting an electronic component and a substrate with each other and mechanically connecting them.

In order to achieve the above object, the present invention provides:
A method of electrically connecting a substrate having a first electrode for connection and an electronic component having a second electrode for connection via the first electrode and the second electrode,
Disposing a conductive paste on the first electrode of the substrate;
Disposing a thermosetting resin sheet in a non-formation region of the first electrode of the substrate;
The electronic component is mounted on the substrate so that the second electrode and the first electrode of the substrate are in contact with each other, and heated at a temperature of 80 to 150 ° C. under a pressure of 0.1 Pa or less. And thermally curing the conductive paste and the thermosetting resin sheet simultaneously to electrically connect the electronic component to the substrate;
It is related with the connection method of an electronic component characterized by comprising.

  As described above, according to the present invention, it is possible to provide a novel method capable of easily and electrically connecting the electronic component and the substrate.

It is process drawing for demonstrating the connection method of the electronic component in embodiment. It is process drawing for demonstrating the connection method of the electronic component in embodiment. It is process drawing for demonstrating the connection method of the electronic component in embodiment. It is process drawing for demonstrating the connection method of the electronic component in embodiment. It is process drawing for demonstrating the connection method of the electronic component in embodiment.

  Hereinafter, other features and advantages of the present invention will be described in detail based on embodiments for carrying out the invention.

1 to 5 are process diagrams for explaining a method of connecting electronic components in the present embodiment.
First, as shown in FIG. 1, a substrate 11 on which a land portion 12 as a first electrode is formed is prepared. The substrate 11 can be composed of, for example, a glass substrate, a ceramic substrate, a resin substrate (BT, PET, etc.), a glass epoxy substrate (FR-4, FR-5), a metal plate whose surface is coated with a metal oxide, or the like. .

  Next, as shown in FIG. 2, a conductive paste 13 is applied on the land portion 12 of the substrate 11. As the conductive paste 13, a paste containing resin as a base resin and added with conductive particles can be used. Examples of the conductive particles used here include metal particles such as gold, silver, and nickel. In addition, as the resin, various materials such as epoxy resin, acrylic resin, polyurethane resin, polystyrene resin, polyester resin, polyimide resin, phenol resin, and silicone resin can be used. You can also. Among these, an epoxy resin excellent in terms of viscosity, heat resistance and the like is preferably used. The resin is desirably liquid at room temperature of 25 ° C. An inorganic filler such as silica may be added to the resin for the purpose of obtaining resin properties necessary for ensuring connection reliability.

  As a commercially available conductive paste, for example, Kyocera Chemical Chemite CT265L using epoxy resin as a base resin and silver as conductive particles is preferably used. The conditions for thermosetting are 1.5 hours at 100 ° C.

  The conductive paste 13 can be applied by, for example, a method using a dispenser or a screen printing method. The application method is not particularly limited.

 Next, as shown in FIG. 3, a thermosetting resin sheet 14 is disposed on the substrate 11 in a region where the land portion 12 and the conductive paste 13 are not formed. The thermosetting resin sheet 14 is preferably such that, for example, the melt viscosity at 100 ° C. before curing is 0.4 to 100 Pa · s and the gel time is 20 to 300 minutes.

  When the melt viscosity at 100 ° C. before curing is less than 0.4 Pa · s, the fluidity of the thermosetting resin sheet 14 at the time of heat curing is increased, and the melt is melted into the land portion 12 and the conductive paste 13 on the substrate 11. When the resin enters and mixes and is connected to an electronic component in a later process, a problem may occur in electrical connectivity. On the other hand, when the melt viscosity at 100 ° C. before curing exceeds 100 Pa · s, the fluidity of the thermosetting resin sheet 14 at the time of heat curing becomes low, and voids are generated in the thermosetting resin sheet 14 after curing. There is a case. Therefore, the substrate 11 and the electronic component may not be mechanically firmly connected.

  In addition, in order to exhibit the effect mentioned above more notably, it is preferable that the melt viscosity in 100 degreeC before hardening is 0.5-20 Pa.s, and is 0.7-5.0 Pa.s. It is more preferable.

  Further, if the gel time at 100 ° C. is outside the above range, it becomes difficult to cure the conductive paste 13 and the thermosetting resin sheet 14 at a time as shown in the following steps. The gel time is particularly preferably within 60 minutes.

  The above-mentioned melt viscosity is obtained by using the thermosetting resin sheet 14 in a rheometer (Rhenetic Scientific, ARES) using a 25 mmφ parallel plate at a constant temperature of 100 ° C., strain 50% (maximum), angular velocity 50 rad / The viscosity after 3 minutes is determined under s. Moreover, the gel time was calculated | required by measuring the time until the thermosetting resin sheet 14 becomes a gel in a 100 degreeC oil bath (test tube method, JISC2105).

  The thermosetting resin sheet 14 that satisfies the above-described characteristics includes, for example, (A) a liquid bisphenol type epoxy resin, (B) a solid polyfunctional epoxy resin having a softening point of 70 ° C. or less, (C) a curing agent for epoxy resin, (D) Mass ratio of inorganic filler and (E) flame retardant, (A) liquid bisphenol type epoxy resin and (B) solid polyfunctional epoxy resin having a softening point of 70 ° C. or less (A) / (B) Is 10/90 to 30/70, and (D) the content of the inorganic filler can be 10% to 80% by mass of the thermosetting resin.

  The liquid bisphenol type epoxy resin used as the component (A) is not particularly limited as long as it is a liquid bisphenol type compound having two or more epoxy groups in one molecule. For example, bisphenol A type and bisphenol F A mold is preferred. Among these, liquid bisphenol A type epoxy resin is preferably used. Specific examples thereof include “DER383J” manufactured by Dow Chemical Company, “807” (epoxy equivalent 170) manufactured by Mitsubishi Chemical Corporation, and “R140P manufactured by Mitsui Chemicals, Inc. (Epoxy equivalent 188) or the like.

  In the present embodiment, the liquid bisphenol type epoxy resin refers to a bisphenol type epoxy resin that exhibits a liquid state at 25 ° C.

  Examples of the solid polyfunctional epoxy resin having a softening point of 70 ° C. or lower used as the component (B) include a mixture of biphenyl skeleton-containing aralkyl epoxy resin and a mixture of dicyclopentadiene epoxy resin. Examples of commercially available solid polyfunctional epoxy resins having a softening point of 70 ° C. or lower include “NC3000 (softening point 57 ° C.)”, “NC3000H (softening point 70 ° C.)” manufactured by Nippon Kayaku Co., Ltd. “YDCN704 (softening point 90 ° C.)” or the like is preferably used.

  In this embodiment, (A) a liquid bisphenol-type epoxy resin and (B) a solid polyfunctional epoxy resin having a softening point of 70 ° C. or less are used in combination, that is, thermosetting containing two types of epoxy resins having different melting points. By using the curable resin, it is possible to obtain the thermosetting resin sheet 14 that exhibits a sheet-like behavior at room temperature and a liquid behavior at high temperature.

  In the thermosetting resin composition, the mass ratio (A) / (B) of (A) liquid bisphenol type epoxy resin and (B) solid polyfunctional epoxy resin having a softening point of 70 ° C. or less is 10/90. It must be in the range of ~ 30/70. When the liquid epoxy resin is less than the above range or the softening point of the solid epoxy resin exceeds 70 ° C., cracking or chipping occurs when the thermosetting resin sheet 14 is produced from the thermosetting resin composition. It is not preferable.

  Moreover, when there are more liquid epoxy resins than the said range, or the softening point of a solid epoxy resin is too low, it will become difficult to manufacture the thermosetting resin sheet 14 from the said thermosetting resin composition.

  In order to achieve the above-described effects more significantly, the mass ratio (A) / (B) is more preferably in the range of 15/85 to 25/75, and the solid epoxy resin The lower limit of the softening point is usually preferably about 40 ° C.

  There is no restriction | limiting in particular as a hardening | curing agent for epoxy resins used as (C) component, From what is conventionally used as a hardening | curing agent of an epoxy resin, arbitrary things can be selected suitably and used, for example, an amine. Type, phenol type, acid anhydride type and the like. Preferred examples of the amine curing agent include dicyandiamide and aromatic diamines such as m-phenylenediamine.

  In addition, the said thermosetting resin composition can be made to contain the hardening accelerator for epoxy resins as needed. There is no restriction | limiting in particular as this hardening accelerator for epoxy resins, From the things conventionally used as a hardening accelerator of an epoxy resin, arbitrary things can be selected suitably and can be used. For example, ureas such as aromatic dimethylurea and aliphatic dimethylurea can be exemplified.

  (D) There is no restriction | limiting in particular as an inorganic filler used as a component, For example, silicas, such as fused silica and spherical silica; A thing normally used, such as an alumina, can also be used, and also water which has a flame-retardant effect Aluminum oxide and magnesium hydroxide can also be used. As the aluminum hydroxide compound, for example, “H42M” manufactured by Showa Denko KK can be preferably used.

  The mass average particle diameter of the inorganic filler is preferably in the range of 1 to 30 μm from the viewpoint of workability during production and filling efficiency. The mass average particle diameter is a value measured by a laser diffraction scattering method (for example, manufactured by Shimadzu Corporation, apparatus name: SALD-3100).

  As the inorganic filler, an aluminum hydroxide compound or spherical silica is preferable. For example, the former is preferably “H42M” manufactured by Showa Denko KK, and the latter is, for example, “FB-959 manufactured by Denki Kagaku Kogyo. (Mass average particle diameter: 25 μm) ”is preferable.

  Content of an inorganic filler needs to be 10-80 mass% with respect to the whole quantity of the said thermosetting resin composition. When the content is less than 10% by mass, when the thermosetting resin sheet 14 is produced from the thermosetting resin composition, a molten resin is used when fixing electronic components using the sheet 14 as described below. The fluidity of the resin becomes high and is mixed with the conductive paste 13, and the cured product is likely to warp and twist. On the other hand, if it exceeds 80% by mass, the thermosetting resin sheet 14 is cracked or chipped, and the fluidity at the time of melting is lowered, causing problems such as a decrease in adhesiveness of the thermosetting resin sheet 14. Since it becomes easy, it is not preferable.

  When manufacturing the thermosetting resin sheet 14 from the said thermosetting resin composition, it carries out as follows, for example. That is, the components constituting the thermosetting resin composition are sufficiently kneaded at a kneading temperature of about 50 to 110 ° C. with a kneader, a two-roller, a continuous kneader, or the like, and then the thermosetting resin composition obtained is obtained. Then, the thermosetting resin sheet 14 is manufactured by pressing with a molding machine under conditions of a temperature of about 50 to 100 ° C. and a pressure of 0.5 to 1.5 MPa.

  In addition, as for the thickness of the thermosetting resin sheet 14, 20-100 micrometers is preferable. When it is less than 20 μm, it is not preferable from the viewpoint of handling workability with the thermosetting resin sheet 14 alone. On the other hand, when the thickness exceeds 100 μm, the bonding thickness of the electronic component to the substrate 11 increases, and the obtained electronic component assembly becomes thick.

  Next, as shown in FIG. 4, an electronic component 15 is prepared. An electrode pad 16 as a second electrode is formed on the lower surface of the electronic component 15. A metal bump electrode 17 is formed on the electrode pad 16 by electrolytic plating via a barrier metal film such as Cr—Cu or Ti—Pd. The metal electrode bump 17 can be made of, for example, Au, Ag, or Cu.

  Moreover, it can also be set as a solder bump by supplying a solder material instead of the metal bump electrode 17, and reflowing.

  The height (thickness) of the metal bump electrode 17 can be set to 3 to 30 μm, for example.

  In the present embodiment, the conductive paste 13 is provided on the land portion 12 of the substrate 11, but may be provided on the metal bump electrode 17.

 Thereafter, the electronic component 15 is placed on the substrate 11 so that the positions of the metal bump electrodes 17 of the electronic component 15 and the conductive paste 13 of the substrate 11 coincide with each other, and 80 to 150 under a pressure of 0 to 0.1 Pa. Heat to a temperature of about ℃. And after making the electrically conductive paste 13 and the thermosetting resin sheet 14 fuse simultaneously, it cools and the electrically conductive paste 13 and the thermosetting resin sheet 14 are hardened collectively. As a result, as shown in FIG. 5, the substrate 11 and the electronic component 15 are electrically connected by the electrical connection body 18 that is a cured product such as the conductive paste 13 and the thermosetting resin sheet 14. It is mechanically connected by the cured product 19.

  As described above, in this embodiment, the conductive paste 13 and the thermosetting resin sheet 14 are collectively melted and cured, and the substrate 11 and the electronic component 15 are electrically and mechanically connected. In addition, it is sufficient to carry out a one-step heating process. In addition, since the conductive paste 13 and the thermosetting resin sheet 14 are fluidized simultaneously by the heat treatment described above, the pressure applied to the electronic component 15 can be 0.1 Pa at the maximum. Therefore, even when the electronic component 15 is fragile, the electronic component 15 is not destroyed.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. In addition, the various characteristics in each example were calculated | required according to the method shown below.

(1) Melt Viscosity A thermosetting resin sheet was measured (100 ° C.) with a rheometer (RENEmetric Scientific, ARES). That is, for the thermosetting resin sheet piece, the viscosity after 3 minutes was obtained using a 25 mmφ parallel plate in a rheometer under a constant temperature of 100 ° C., a strain of 50% (maximum), and an angular velocity of 50 rad / s. It is a thing.

(2) Gel time Based on the test tube method of JIS C2105, the time until a sheet-like resin composition became a gel was measured in an oil bath at 100 ° C.

(3) Exudation to electrode part The electronic component after a connection was cut | disconnected, the electrode part was observed visually, and the following references | standards evaluated.
○: Exudation area of resin is less than 5% of electrode area △: Exudation area of resin is not less than 5% and less than 15% of electrode area ×: Exudation area of resin is not less than 15% of electrode area

(4) Conductivity The resistance value was measured with a tester and evaluated according to the following criteria.
○: Resistance value is less than 100Ω ×: Resistance value is 100Ω or more

(5) State of electronic component After both the conductive paste and the thermosetting resin sheet were cured, the appearance of the electronic component was visually examined and evaluated according to the following criteria.
○: No deformation, cracking or chipping of electronic parts ×: Deformation, cracking or chipping of electronic parts

(Manufacture of thermosetting resin sheet: Examples 1 to 5)
Each raw material of the composition shown in Table 1 was charged into a kneader and stirred and mixed at 75 ° C. for 1 hour to prepare each resin composition. Next, each resin composition was cooled to 30 ° C. and then press-molded with a molding machine under the conditions of 70 ° C. and 1.0 MPa to obtain a thermosetting resin sheet having a thickness of 0.5 mm. Table 1 shows the evaluation results of various characteristics in each example.

(Connection of electronic components)
(Examples 1-5)
After applying a conductive paste using a dispenser on a pre-formed electrode part on a substrate, a thermosetting resin sheet having characteristics corresponding to each example in Table 1 is disposed adjacent to the conductive paste application part. did. Then, after mounting the electronic component so as to cover both the conductive paste and the thermosetting resin sheet, the thermosetting resin sheet is melted by heating to a temperature of 80 ° C. to 150 ° C. for 2 hours without applying pressure. The conductive paste was melted and then cured, and physical fixing was performed together with the electrical connection between the electronic component and the substrate. The results are shown in Table 1.

(Comparative Example 1)
Thermosetting obtained by mixing 90 parts by mass of Epicoat 828 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.), 1 part by mass of dicyandiamide, and 0.5 parts by mass of imidazole 2E4MZ (manufactured by Shikoku Chemicals). In the resin, FB3LDX (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.) of silica having an average particle diameter of 3.4 μm and SE2100 (trade name, manufactured by Admatex Co., Ltd.) of silica having an average particle diameter of 0.6 μm are used as inorganic fillers. 10 parts by mass of mixed silica premixed at a ratio of 3: 1 was added and dispersed to obtain an adhesive.

  The obtained adhesive was applied adjacent to the conductive paste application part on the substrate electrode, but both were mixed and the conductivity after curing was not good.

(Comparative Example 2)
Epicoat 828 of bisphenol A type epoxy resin (made by Japan Epoxy Resin Co., Ltd., trade name) 2.9 parts by mass, EPPN-501HY of trishydroxyphenylmethane type epoxy resin (made by Nippon Kayaku Co., Ltd., trade name) 2.9 parts by mass DL-65 (product name, manufactured by Meiwa Kasei Co., Ltd.) 3.5 parts by mass of novolak type phenol resin, Teisan resin SG-P3 (product name) manufactured by Nagase ChemteX Corporation, 9.5 parts by mass, PP-200 of triphenylphosphine (made by Hokuko Chemical Co., Ltd., trade name) 0.13 parts by mass, FB-7SDC (made by Denki Kagaku Kogyo Co., trade name) of spherical fused silica (average particle size: 5.5 μm) 0 parts by mass and 66 parts by mass of methyl ethyl ketone were added to prepare a resin composition. Next, the composition was coated on a polyester film with a coater and dried to obtain a thermosetting resin sheet.

 After placing the obtained thermosetting resin sheet on the substrate by the same operation as in Example 1, after mounting the electronic component so as to cover both the conductive paste and the thermosetting resin sheet, as in Example, It vacuum-pressed for 1 minute on the conditions of 100 degreeC and the pressure of 300 kPa. After opening to the atmosphere, the substrate was put into an oven at 175 ° C. for 1 hour to heat and cure the thermosetting resin sheet. However, in this method, the electronic component is deformed.

(Comparative Example 3)
The same operation as in Comparative Example 2 was performed except that the EVA-based hot melt sheet Elfhan OH (made by Nihon Matai Co., Ltd., trade name) was used. As in Comparative Example 1, the molten resin and the conductive paste were mixed and conducted. The properties were not good.

Each component used in the present example is as follows.
1. Liquid epoxy resin DER383J: bisphenol A type epoxy resin manufactured by Dow Chemical Co. (epoxy equivalent: 190)
2. Solid epoxy resin NC3000: polyfunctional epoxy resin containing biphenyl skeleton manufactured by Nippon Kayaku Co., Ltd. (epoxy equivalent: 285, softening point: 57 ° C.)
3. Curing agent DICY: Dicyandiamide manufactured by Nippon Carbide Corporation 4. Curing accelerator U-CAT3502T: Aromatic dimethylurea manufactured by Sun Apro Inorganic filler H42M: Showa Denko Co., Ltd. aluminum hydroxide (particle diameter: 1.5 μm)
6). Conductive paste CT265L: Silver paste manufactured by Kyocera Chemical

  As is apparent from Table 1, in the examples, there was no deformation of the electronic parts, and the results of conductivity and adhesiveness were good. On the other hand, in Comparative Example 1 using the liquid adhesive, a conduction failure caused by mixing of the conductive paste and the liquid adhesive occurred. In Comparative Example 2, a thermosetting resin sheet having a different component from that of the example was used, but although the electrical conductivity was good, the electronic component was deformed because a high pressure was required for physical fixation. Further, in Comparative Example 3 using the thermoplastic resin sheet, not only the same result as in Comparative Example 1 was obtained, but also the decrease in adhesive strength was large.

  The present invention has been described in detail based on the above specific examples. However, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

11 Substrate 12 Land (first electrode)
13 conductive paste 14 thermosetting resin sheet 15 electronic component 16 electrode pad (second electrode)
17 Metal bump electrode 18 Electrical connection body 19 Hardened material of thermosetting resin sheet

Claims (3)

A method of electrically connecting a substrate having a first electrode for connection and an electronic component having a second electrode for connection via the first electrode and the second electrode,
Disposing a conductive paste on the first electrode of the substrate;
Disposing a thermosetting resin sheet in a non-formation region of the first electrode of the substrate;
The electronic component is mounted on the substrate so that the second electrode and the first electrode of the substrate are in contact with each other, and heated at a temperature of 80 to 150 ° C. under a pressure of 0.1 Pa or less. And thermally curing the conductive paste and the thermosetting resin sheet simultaneously to electrically connect the electronic component to the substrate;
A method for connecting electronic components, comprising:   The melt viscosity at 100 ° C before curing of the thermosetting resin sheet is 0.4 to 100 Pa · S, and the gel time at 100 ° C is 20 to 300 minutes. To connect electronic components. The thermosetting resin sheet comprises (A) a liquid bisphenol type epoxy resin, (B) a solid polyfunctional epoxy resin having a softening point of 70 ° C. or less, (C) a curing agent for epoxy resin, (D) an inorganic filler, and ( E) comprising a thermosetting resin composition containing a flame retardant,
(A) Mass ratio (A) / (B) of liquid bisphenol type epoxy resin and (B) solid polyfunctional epoxy resin having a softening point of 70 ° C. or lower is 10/90 to 30/70, (D) The method for connecting electronic parts according to claim 1 or 2, wherein the content of the inorganic filler is 10% by mass to 80% by mass of the thermosetting resin composition.

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