JP2004031975A - Connecting equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting equipment for mounting chip elements on a substrate, that is useful when the height of the chips are different or the chips are mounted on both sides of a substrate. <P>SOLUTION: The connecting equipment comprises a closed container; an inlet and outlet for getting in and out a sample that is provided for the closed container, and air intake and exhaust openings; an air intake and exhaust equipment connected to the air intake and exhaust opening that can change the kind of gases, and a heater for heating the closed container. The connecting equipment can heat an adhesive formed on the connecting objects in the closed container under a hydrostatic pressure. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a connection device used for mounting a chip component on a substrate.
[0002]
[Prior art]
As semiconductor chips and electronic components have become smaller and thinner, circuits and electrodes used for them have become higher in density and definition. For connection of such fine electrodes, a method using an adhesive has recently been frequently used. In this case, conductive particles are mixed in the adhesive to obtain an electrical connection in the thickness direction of the adhesive by pressing (for example, JP-A-55-104007). There is a method in which electrical connection is obtained by direct contact of fine irregularities on the electrode surface by pressure (for example, JP-A-60-262430). The connection method using an adhesive allows connection at a relatively low temperature, and the connection part is flexible, so it has excellent reliability. In addition, when a film or tape adhesive is used, a certain thickness is used. It is attracting attention because it is possible to automate the mounting line because it is supplied in a long shape. In recent years, a multi-chip module (MCM) that develops the above method and mounts a plurality of chips on a relatively small substrate at a high density has attracted attention. In this case, it is common practice to first form an adhesive layer on the entire surface of the substrate, peel off the separator, if any, and then align and bond the substrate electrode and the chip electrode. There are many types of chips (hereinafter referred to as chips) such as a semiconductor chip, an active element, a passive element, a resistor, and a capacitor used for the MCM.
[0003]
[Patent Document 1]
JP-A-55-104007 [Patent Document 2]
Japanese Patent Application Laid-Open No. Sho 60-262430
[Problems to be solved by the invention]
There are many types of chips used for the MCM, and accordingly, chip sizes (areas and heights) are various. For this reason, when connecting to a substrate using an adhesive, there is a problem that has not been encountered in a conventional method such as a thermocompression bonding method with the substrate. For example, when the chip height is different or when mounting on both sides of the board, the conventional method of pressing parallel mounted molds with hydraulic or pneumatic pressure, or the parallel mounting of rubber or metal In a so-called roll method in which pressure is applied by a press roll, if the chip height is different as shown in FIG. That is, in these press methods and roll methods, pressure is applied between dies and rolls, for example, pressure is applied between the platen 8 and the press die 9 installed in parallel. , 2a, 2b or 2 ', 2a', 2b ') or when a chip is mounted on both sides of the substrate (2, 2', etc.), the pressurized state is not constant, and the connection between the electrodes becomes insufficient due to insufficient connection. Reliability cannot be obtained. In particular, when mounting on both surfaces (3 and 3 'surfaces) of the substrate, there are few cases where the chip positions are installed symmetrically on the front and back, so that the bonding of fine electrodes that requires uniform pressure without pressure unevenness is required. There is no suitable means for applying pressure. The present invention has been made in view of the above-described drawbacks, and provides a connection device used for mounting a chip component effective on a substrate when the chip height is different or when mounting on both surfaces of the substrate.
[0005]
[Means for Solving the Problems]
The present invention relates to a connection device used to mount a chip component on a substrate, and changes the type of gas connected to a closed container, a suction / exhaust port provided in the closed container, a sample inlet / outlet, and a suction / exhaust port. It has a possible suction / exhaust device and a heating means for heating the closed container, and is characterized in that the adhesive formed on the object to be connected in the closed container can be heated under hydrostatic pressure. The adhesive is preferably a thermoplastic material or a curable material, and is preferably an adhesive containing conductive particles.
A connection device that mounts a chip on a substrate is a device under the hydrostatic pressure with an adhesive interposed between the electrode forming surface on the substrate and the chip electrode, with the substrate electrode and the chip electrode facing the electrode aligned. Heat with. Further, when mounting the chip on the substrate, the connection device of the present invention positions the electrode of the substrate and the electrode of the chip facing the electrode with an adhesive between the electrode forming surface on the substrate and the chip electrode. After conducting the continuity test in the state of being performed, heating can be performed under hydrostatic pressure.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 shows a state in which an adhesive 3 is interposed between the surface of the substrate 1 on which the electrodes 5 are formed and the electrodes 4 of the plurality of chips 2, 2a, 2b, and the electrodes of the opposing chips are aligned. It is a cross section schematic diagram. The surface on which the electrode 5 is formed on the substrate 1 may be one side (FIG. 1) or both sides as shown in FIG. Either the electrode B5 on the substrate 1 or the electrode A4 on the chip 2 may use a wiring circuit as a connection terminal as it is, or may further form a protruding electrode. It is preferable that the electrodes 4 and / or 5 have a protruding shape, since pressure can be intensively obtained between the opposing electrodes, so that electrical connection is easy. The adhesive 3 may be in the form of a film, liquid, or paste. In the method of aligning the electrode of the chip with the adhesive to be connected and the electrode of the substrate, the electrode B5 of the substrate 1 to be connected and the electrode A4 of the chip 2 are aligned using a microscope or an image recognition device. At this time, the use and use of a positioning mark are also effective. The holding of the substrate 1 and the chip 2 after the alignment can be performed by temporary connection using the adhesiveness of the adhesive 3 or cohesive force. Auxiliary means such as clips and adhesive tapes can be used alone or in combination. The temporary connection may be non-uniform as long as the heating and pressurizing is to some extent, and therefore, a conventionally used thermocompression bonding apparatus can be used. At this time, it is also possible to conduct a continuity test between the electrodes to be connected. Since the continuity test can be performed on the adhesive in an uncured or insufficiently cured state, the adhesive can be easily repaired (operation of peeling off a defective connection portion, cleaning it, and then reconnecting it). Similarly, it is also possible to add a step of removing excess adhesive around the chip. According to this method, the curing reaction of the adhesive proceeds by heating and pressurizing the good connected product after the continuity test in the closed container which is the connecting device of the present invention described below, so that the defective product is regenerated little by little. Loss time is short.
[0007]
FIG. 2 shows that the electrode of the chip and the electrode of the substrate for which electrode alignment has been completed are placed in a sealed container 6 capable of withstanding hydrostatic pressure, which is the connection device of the present invention, and heated and pressurized, and are placed on the same substrate. Obtain electrical connections for a plurality of chips. Examples of the closed container 5 include a pressure cooker, a pressure cooker, and an autoclave. By providing the air intake / exhaust hole 7 in the closed container 6, the operation of pressurizing and depressurizing is simple, and the pressure can be controlled. Although not shown, a sample inlet / outlet is provided. The hydrostatic pressure in the present invention indicates a state in which a constant pressure acts on the external surface of the object perpendicularly (exemplified by an arrow P in FIG. 2).
Here, considering the surface area of the connection structure with reference to FIG. 2, the chip area S is generally 2 to 20 mm □, whereas the thickness t of the connection portion is 0.1 mm or less, and often 30 μm or less. Since S is overwhelmingly larger than t, the pressure applied to the chip area S in the thickness direction of the connection portion is large, and the pressure in the electrode connection direction can be easily obtained.
[0008]
As described above, as shown in FIGS. 1 and 3, the electrodes 4 of the chips 2 (a to c) having a plurality of various shapes and sizes are densely attached to the electrodes 5 of the relatively small substrate 1 using the adhesive 3. A multi-chip module (MCM) to be mounted is obtained. Examples of the substrate 1 include plastic films such as polyimide and polyester, composites such as glass fiber / epoxy, semiconductors such as silicon, and inorganic materials such as glass and ceramics.
[0009]
As the adhesive 3 used in the present invention, a thermoplastic material or a material that is curable by heat or light (curable material) can be widely applied. Since these are excellent in heat resistance and moisture resistance after connection, it is preferable to use a curable material. Among them, an epoxy adhesive containing a latent curing agent is particularly preferable because it can be cured in a short time, has good connection workability, and has excellent adhesiveness in terms of molecular structure. The latent curing agent has a relatively clear active point at which the reaction is initiated by heat and / or pressure, and is suitable for the connection device of the present invention involving a heat or pressure step.
Examples of the latent curing agent include imidazole-based, hydrazide-based, boron trifluoride-amine complex, amine imide, polyamine salt, onium salt, dicyandiamide, and the like, and modified products thereof. Can be used as a mixture. These are so-called ion-polymerizable catalyst-type curing agents such as anion- or cationic-polymerization types, and are preferable because they can easily obtain fast curability and require little consideration of chemical equivalents. Among them, imidazole-based ones are non-metallic ones, are less likely to cause electrolytic corrosion, and are particularly preferable in terms of reactivity and connection reliability. In addition, as the curing agent, polyamines, polymercaptans, polyphenols, acid anhydrides, and the like can be applied, or the curing agent can be used in combination with the catalyst-type curing agent. Further, a microcapsule-type curing agent whose core is a curing agent and whose surface is coated with a polymer substance or an inorganic substance is preferable because contradictory characteristics such as long-term storage property and rapid curing property can be achieved at the same time. The activation temperature of the curing agent is preferably from 40 to 200C. If the temperature is lower than 40 ° C., the temperature difference from room temperature is small and a low temperature is required for storage. If the temperature is higher than 200 ° C., heat is exerted on other members of the connection. More preferred. The activation temperature indicates a peak temperature of heat generated when the mixture of an epoxy resin and a curing agent is heated at a rate of 10 ° C./min from room temperature using a DSC (differential scanning calorimeter) as a sample. When the activation temperature is on the low temperature side, the reactivity is superior, but the storage stability tends to decrease. Temporary connection by heat treatment at or below the activation temperature of the curing agent improves the preservability of the substrate with the adhesive, and provides a highly reliable chip connection at or above the activation temperature.
[0010]
It is preferable to add conductive particles or insulating particles to these adhesives 3 because they act as a thickness maintaining material during heating and pressurization during the production of a chip with an adhesive. In this case, the ratio of the conductive particles and the insulating particles is about 0.1 to 30% by volume, and 0.5 to 15% by volume to make the conductive particles anisotropically conductive. As the adhesive layer 3, a multi-layer component in which an insulating layer and a conductive layer are separately formed is also applicable. In this case, high resolution electrode connection is possible because the resolution is improved. Examples of the conductive particles include metal particles such as Au, Ag, Pt, Ni, Cu, W, Sb, Sn, and solder, carbon, and graphite. A core material made of a polymer such as glass, ceramics or plastic may be coated with a conductive layer made of the above-mentioned material. Further, insulating coated particles obtained by coating a conductive material with an insulating layer, and a combination of conductive particles and insulating particles of glass, ceramics, plastics, and the like are also applicable because resolution is improved. Among these conductive particles, those formed by forming a conductive layer on a polymer nucleus material such as plastic or a hot-melt metal such as solder are deformable by heating and pressing or pressurizing. This is preferable because the area is increased and the reliability is improved. In particular, when a polymer is used as a core, it is particularly preferable because it does not exhibit a melting point unlike solder, so that the softened state can be controlled widely at the connection temperature and it is easy to cope with variations in electrode thickness and flatness. In the case of hard metal particles such as Ni and W, or particles having a large number of protrusions on the surface, for example, conductive particles penetrate electrodes and wiring patterns. Therefore, even when an oxide film or a contamination layer is present, a low connection resistance is obtained. It is preferable because it improves the reliability. In the above description, the case where the film adhesive is used has been described, but the present invention can be similarly applied to a liquid or paste form. Further, the case where the chip heights are different has been described, but the case where the chip heights are the same is also applicable.
[0011]
ADVANTAGE OF THE INVENTION According to the connection apparatus of this invention, since the pressure in a closed container is constant even if it changes places, since many MCMs can be processed at once, the mass production effect is high. In addition, since it is pressurized with gas, an expensive mold is unnecessary, and by changing the type of gas, it can be applied to various adhesives such as heat, moisture, and anaerobic. The closed container can perform the heating and pressurizing operation at once by, for example, introducing a heating gas or holding the container in a heating furnace. For many substrates. According to the connection device of the present invention, a continuity test can be performed before full-scale curing in a closed container, so that when a defective connection portion is found, the adhesive is in a state where the curing reaction is insufficient, so the chip Peeling and subsequent cleaning using a solvent are also extremely simple, and repair work (work for peeling off defective connection parts, cleaning them, and then reconnecting them) is easy. After the curing of the adhesive, it is extremely difficult to peel off the chip and clean it with a solvent, but according to this embodiment, even when the chip exists on a narrow substrate, the repair work is easy. is there. According to a preferred embodiment of the present invention, a chip can be formed on a substrate by a heat treatment at or below the activation temperature of the latent curing agent used for the adhesive, so that the preservability of the adhesive after the temporary connection is improved. In addition, when heating and pressing in a closed container at the activation temperature or higher, the adhesive can be set freely, such as shortening the curing time of the adhesive, and the cohesive force of the adhesive is sufficiently high by taking out from the container after connection and cooling. Since the connection can be performed in a state, a connection excellent in chip reliability can be obtained.
[0012]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
Example 1
(1) Preparation of Adhesive Ratio of phenoxy resin (PKHA, high molecular weight epoxy resin manufactured by Union Carbide) and liquid epoxy resin containing a microcapsule-type latent curing agent (Novacure HP-3942HP, manufactured by Asahi Kasei; epoxy equivalent: 185) Was set to 30/70 to obtain a 30% by weight solution of ethyl acetate. To this solution, 2% by volume of conductive particles formed by forming a metal coating of Ni / Au with a thickness of 0.2 / 0.02 μm on polystyrene particles having a particle size of 3 ± 0.2 μm were added and mixed and dispersed. A connection electrode that has a copper circuit with a height of 18 μm on a glass epoxy substrate (FR-4 grade) with a thickness of 5 mm x 11 mm and a thickness of 0.8 mm, and a circuit end corresponding to a bump pitch of an IC chip described later. The dispersion was applied by screen printing to a connection region of a glass epoxy substrate having the above, and dried at 100 ° C. for 20 minutes to obtain an adhesive layer having a thickness of 20 μm on the electrode. The activation temperature of this adhesive layer by DSC is 120 ° C.
[0013]
(2) Positioning and connection of electrodes Three IC chips (height: 0.3, 0.55, 1.0 mm) were arranged on the substrate with the adhesive, and the positions of the electrodes were aligned by a CCD camera. . The adhesive was in a slightly tacky state even at room temperature, and could be easily held on the substrate by pressing it against the bonding surface at room temperature to obtain a temporary mounting substrate for the chip. The chip-attached substrate was put into a pressure cooker of a pressure-cooker tester, treated at 120 ° C., 20 kgf / cm ² for 10 minutes with air pressure, and cooled to room temperature and taken out.
(3) Evaluation The electrodes of each chip and the substrate electrodes could be connected well. Since the adhesive was present only near the chip, there was almost no unnecessary adhesive on the substrate surface. In this example, three IC chips having different heights could be connected to the substrate surface.
[0014]
Example 2
Same as Example 1, except that an intermediate inspection step for inspecting the electrical connection between the electrodes after obtaining the temporary mounting substrate of the chip was provided. First, when the connection resistance at each connection point was measured and inspected with a multimeter at 70 ° C. and 10 kgf / mm ² while applying pressure with a spring device, one IC chip was abnormal. Then, the abnormal chip was peeled off, and the same connection as described above was performed with a new chip. In this example, since the curing reaction of the adhesive was inadequate, peeling of the chip and subsequent cleaning using acetone were extremely simple, and the repair work was easy. Also, the excess adhesive around the chip could be easily removed with acetone. After the above-mentioned energization inspection step and repair step, they were placed in a pressure cooker and processed as in Example 1. However, good connection characteristics were shown. After the adhesive has been cured, it is extremely difficult to separate the chip and clean it with a solvent.However, according to the present embodiment, even when a large number of chips are present on a narrow substrate, the repair work is difficult. It was very easy.
[0015]
Example 3
Same as Example 1 except that a double-sided board as illustrated in FIG. 3 was used. The electrodes of each chip and the substrate electrodes could be connected well. In the present embodiment, the lower surface of the chip is temporarily reinforced by pressing the chip against the adhesive surface with a heat-resistant adhesive tape when the pressure cooker is processed. I did not.
[0016]
Example 4
Same as Example 1 except that the type of adhesive was changed. That is, the conductive particles were not added. Also in this case, the electrode of each chip and the substrate electrode could be connected well. This is probably because the bump and the circuit end of the glass epoxy substrate are in direct contact and are fixed with an adhesive.
[0017]
【The invention's effect】
As described in detail above, according to the present invention, an adhesive is interposed between an electrode forming surface on a substrate and a chip electrode, and an adhesive is interposed between an electrode of the substrate and an electrode of a chip facing the electrode. Since heating and pressurization are performed under hydrostatic pressure in a state where is aligned, an effective chip can be mounted when the chip height is different or when mounting is performed on both surfaces of the substrate.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating a state in which an adhesive is interposed between an electrode on a substrate and a chip electrode to perform alignment.
FIG. 2 is a schematic cross-sectional view illustrating a connection device for explaining an embodiment of the present invention.
FIG. 3 is a schematic sectional view illustrating a conventional connection method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Chip 3 Adhesive 4 Electrode A
5 Electrode B 6 Sealed container 7 Inlet / outlet 8 Surface plate 9 Pressurized type

Claims (3)

A closed container having a closed container, a suction / exhaust port provided in the closed container, a sample inlet / outlet, a suction / exhaust device capable of changing the type of gas connected to the suction / exhaust port, and a heating means for heating the closed container; A connection device capable of heating an adhesive formed on an object to be connected in the device under hydrostatic pressure. The connection device according to claim 1, wherein the adhesive is a thermoplastic material or a curable material. The connection device according to claim 1, wherein the connection device is an adhesive containing conductive particles.

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