WO2004088737A1 - Electronic device producing method - Google Patents

Abstract

A wiring board (10) has an insulative support layer (11) and a conductor layer (12). The support layer (11) is a liquid crystal polymer layer. In mounting an electronic part (21) on the wiring board (10), a thermosetting resin (32) is interposed between the wiring board (10) and the electronic part (12), and the electronic part (21) is disposed on the wiring board (10) with a bump (22) opposed to the connection (21a). Next, the electronic part (21) is heated by a heating and pressing tool (40), and at the same time as the connection (12a), bump (22) and thermosetting resin (32) are heated, the connection (12a) and the bump (22) are pressed. As the thermosetting resin (32), use is made of what will quickly complete curing reaction at relatively low temperatures.

Description

Manufacturing method of electronic device

 The present invention relates to a method for manufacturing an electronic device including a substrate and an electronic component mounted on the substrate.

 Light

Background art

 In general, electronic components such as semiconductor components are mounted on a substrate having a patterned conductor layer as follows. That is, the electrode of the electronic component is electrically connected to the conductor layer of the substrate, and the electrical connection between the electrode of the electronic component and the conductor layer of the substrate is sealed. Sealing of the electrical connection is performed to protect the electrical connection from moisture, oxygen, and the like.

 One of the methods for electrically connecting the electrodes of the electronic component to the conductor layer of the substrate is a method called flip-chip connection. When flip-chip connection is performed, protruding electrodes called bumps are formed on electronic components. In the flip-chip connection, the electronic component is arranged such that the surface of the electronic component having the bump faces the substrate, and the bump and the conductor layer of the substrate are electrically connected directly or via a conductive material. This flip-chip connection is expected to improve the mounting density of electronic components and the electrical characteristics of the electrical connection between the electrodes of the electronic component and the conductor layer of the board, as compared to other connection methods. The improvement of the electrical characteristics of the electrical connection part is, specifically, reduction of the resistance value and the inductance / capacitance of the electrical connection part.

 Conventional flip-chip connections include, for example, Kobayashi, “Flip Chip Bonding Technology,” Monthly Semiconductor, 1989, Press Journal, August 1998, p. As described in 59, there are several connection methods. The following describes four typical connection methods.

The first connection method is a method using a conductive paste. In this first connection method, first, a conductive paste is applied to the bumps, and then the bumps and the conductive layer of the substrate are connected. The bumps and the conductive layers are electrically connected directly or via a conductive paste by mounting the electronic components on the substrate after performing the alignment. In the first connection method, a sealing resin is filled between the electronic component and the substrate, and finally, the sealing resin is heated and cured to perform sealing.

 The second connection method is a method using an anisotropic conductive film. The anisotropic conductive film is a film made of a material in which conductive particles are dispersed in a thermosetting resin. In this second connection method, first, an anisotropic conductive film is interposed between the bump and the conductor layer of the substrate, and then the electronic component is heated and pressed to make the bump and the conductor layer conductive. Electrical connection is made via the particles, and the thermosetting resin is cured to seal. The third connection method is a method using solder. In this third connection method, the first case in which the sealing resin is filled between the electronic component and the substrate after the pump and the conductor layer of the substrate are connected, and the connection between the bump and the conductor layer of the substrate There is a second case in which a sealing resin is interposed between the electronic component and the substrate before performing. In the first case, first, a solder paste is applied to the conductor layer, and then the bumps and the conductor layer are aligned, and the electronic component is mounted on the substrate. In the first case, the solder is heated and melted and then solidified to electrically connect the bump and the conductive layer via the solder. A sealing resin is filled in between, and finally, the sealing resin is heated and cured to perform sealing. In the second case, first, a solder paste is applied to the conductor layer, then, a sealing resin is applied on the substrate, and then the bumps and the conductor layer are aligned and the electronic components are placed on the substrate. To be mounted on. In the second case, next, the solder is heated and melted, and then solidified, thereby electrically connecting the bump and the conductor layer via the solder and sealing the resin by curing the sealing resin. Stop.

The fourth connection method is a method of directly connecting the bump and the conductor layer of the substrate using heat or a load. In the case of using the fourth connection method, for example, gold is used for the material of the bump, and the conductor layer is made of gold or plated. In the fourth connection method, the first case in which the sealing resin is filled between the electronic component and the substrate after the connection between the bump and the conductor layer, and the electronic component before the connection between the bump and the conductor layer There is a second case where a sealing resin is interposed between the substrate and the substrate. You. In the first case, first, the bump and the conductor layer are directly connected, then the sealing resin is filled between the electronic component and the substrate, and finally, the sealing is performed by curing the sealing resin. Do. In the second case, first, a sealing resin is interposed between the electronic component and the substrate, and then the bump and the conductor layer are aligned to mount the electronic component on the substrate. The conductor layer is directly connected by a load, and finally, the sealing is performed by curing the sealing resin.

 Japanese Unexamined Patent Publication No. Heisei 5-4-2603 discloses a laminated body that can be used as a material for a flexible printed wiring board, and is composed of a film made of a liquid crystal polymer and a metal foil. Is described.

 The first connection method in flip-chip connection has a problem that it takes a lot of time to mount electronic components because of the large number of steps. In addition, the first connection method has a problem that it is difficult to cope with a narrow pitch of the electrodes and the conductive layer because the conductive paste has fluidity and is easily spread.

 In the second connection method in the flip-chip connection, the bump and the conductive layer are changed depending on the size and density of the conductive particles in the anisotropic conductive film and the magnitude of the load when pressing the electronic component. Changes the electrical connection state. For example, if the density of the conductive particles in the anisotropic conductive film is too low, poor conduction occurs between the bump and the conductive layer. Also, if the density of the conductive particles in the anisotropic conductive film is too large, there is a possibility that a current leaks between adjacent electrodes. Therefore, the second connection method has a problem that the reliability of the electrical connection between the bump and the conductor layer is poor. The third connection method in flip-chip connection has a problem that it is difficult to cope with a narrow pitch of electrodes and conductor layers because the solder paste has fluidity and is easily spread. In the third connection method, when a sealing resin is interposed between the electronic component and the substrate before connecting the bump and the conductive layer, the flux remains in the sealing resin, and Therefore, there is a problem that the bumps and the conductor layer are corroded.

The fourth connection method in flip-chip connection requires a large load to connect the bump and the conductive layer, and it is difficult to increase the reliability of the connection between the bump and the conductive layer. is there. As described above, in the conventional mounting method of electronic components using flip-chip connection, the electrical characteristics and reliability of the connection between the pump and the conductive layer are improved, and the pitch of the electrodes and the conductive layer is reduced. It has been difficult to mount electronic components on a board in a short time.

 Therefore, the present applicant has proposed a method of mounting an electronic component using flip-chip connection, in which a connection between a conductor layer of a substrate and a bump of the electronic component and a sealing with a thermosetting resin are performed almost simultaneously. Have been considered. In this mounting method, the conductor layer of the board and the pump of the electronic component are brought into contact with a thermosetting resin before curing between the board and the electronic component, and these are heated and pressed. Thereby, the conductive layer of the substrate and the bump are electrically connected and the thermosetting resin is cured. According to this method, the electrical characteristics and reliability of the connection portion between the bump and the conductor layer of the substrate can be improved, the electrode and the conductor layer can be made narrower, and the electronic component can be transferred to the substrate in a short time. Can be implemented.

 By the way, conventionally, as a material of a support layer for supporting a conductor layer in a substrate, particularly a wiring board, a polyimide resin or a material in which glass cloth is impregnated with an epoxy resin (hereinafter referred to as glass epoxy) is often used. Had been. It has been found that when the electronic component is mounted on a substrate whose support layer is made of a polyimide resin or a lath epoxy using the mounting method examined by the present applicant, the following problems occur.

 First, polyimide resins and glass epoxies have relatively high hygroscopicity. Therefore, the support layer made of these materials contains moisture before mounting the electronic component. Therefore, when heat is applied to the substrate during the mounting process of the electronic component, moisture contained in the support layer evaporates, and air bubbles may mix in the thermosetting resin before curing. As a result, defects such as voids may occur in the cured thermosetting resin, that is, the sealing resin.

 Further, the evaporation of water as described above consumes heat. As a result, the temperature rise of the thermosetting resin is suppressed, and the curing of the resin is delayed, and as a result, the curing rate of the resin may decrease. In this case as well, when the curing rate of the sealing resin decreases, it can be said that the sealing resin is defective.

In addition, due to the evaporation of water as described above, water molecules spread in the thermosetting resin before curing. Scatter. Therefore, the curing reaction of the thermosetting resin is inhibited, and as a result, the curing rate of the resin may decrease.

 The thermal conductivity of the support layer made of polyimide resin or glass epoxy is smaller than the thermal conductivity of the support layer made of an inorganic material such as ceramic. Therefore, when the thermosetting resin is heated by heating the electronic component during the mounting process of the electronic component, the portion of the thermosetting resin that is located at a position away from the electronic component is hardened. In some cases, sufficient heat may not be transmitted, and the curing rate of this portion may decrease. On the other hand, when electronic components are mounted on a substrate having a support layer made of an inorganic material such as ceramic by the mounting method studied by the present applicant, the thermal conductivity of the support layer is too large. There is a problem. In other words, when mounting a plurality of electronic components on the same board, it is necessary to arrange thermosetting resin in multiple places on the board in advance, and then mount the electronic components sequentially for each location. Conceivable. In this case, the heat applied to the place where the electronic component is mounted is transferred to the thermosetting resin in other places via the support layer, and the curing reaction of the resin may start. . Disclosure of the invention

 A first object of the present invention is a method for manufacturing an electronic device including a substrate and an electronic component mounted on the substrate, the method comprising the steps of: connecting an electrode of the electronic component to a conductor layer of the substrate; It is an object of the present invention to provide a method of manufacturing an electronic device which can improve the mechanical characteristics and reliability and can prevent defects from occurring in a sealing resin.

 A second object of the present invention, in addition to the first object, is to provide a method of manufacturing an electronic device, which can mount an electronic component on a substrate in a short time.

 A method for manufacturing an electronic device according to the present invention includes: a substrate; and an electronic component mounted on the substrate. The substrate is disposed so as to be adjacent to an insulating support layer and at least one surface of the support layer. And a patterned conductor layer, wherein the electronic component has an electrode connected to the conductor layer.

 The method for manufacturing an electronic device according to the present invention includes:

As a substrate, a support layer is connected to at least an electrode of an electronic component of the conductor layer. Using a substrate that includes a liquid crystal polymer layer that is arranged adjacent to the connection part to be connected, the electrode faces the connection part with an insulating thermosetting resin before curing interposed between the substrate and the electronic component Arranging electronic components on the substrate,

 The connection portion and the electrode are brought into contact, the connection portion and the electrode are pressed so that they are in close contact with each other, and the thermosetting resin is heated, thereby connecting the connection portion and the electrode and curing the thermosetting resin. Process.

 In the method of manufacturing an electronic device according to the present invention, the substrate includes a support layer including a liquid crystal polymer layer arranged so as to be adjacent to at least a connection portion of the conductor layer connected to an electrode of the electronic component. Is used. Then, in the present invention, the electronic component is arranged on the substrate such that the insulating thermosetting resin before curing is interposed between the substrate and the electronic component so that the electrodes face the connection portions. Next, the connection portion and the electrode are brought into contact with each other, the connection portion and the electrode are pressed so that they are in close contact with each other, and the thermosetting resin is heated. The reactive resin cures. The cured thermosetting resin seals the connection between the connection portion and the electrode.

In the method for manufacturing an electronic device according to the present invention, the thermosetting resin contains an epoxy resin and a latent curing catalyst, and has a viscosity obtained by a rheometric measurement at a temperature rising rate of 5 ° CZ for one minute. In one temperature curve, the viscosity of the thermosetting resin is 50 to 9 °. OXIOP a's or less in the temperature range with a width of at least 10 T within the above temperature range, and within the temperature range of 80 to 130, it rises with increasing temperature, and the amount of temperature change it is preferable that shows the behavior that varies s - but 1. 0 X 1 0 ⁵ P a from ^{1. 0 X 1 0 2 P a} 's in the range of 30.

 In the method for manufacturing an electronic device according to the present invention, it is advantageous to use a substrate having a thermal conductivity of the liquid crystal polymer layer in the range of 0.3 to 1WZm ° C. The method for manufacturing an electronic device according to the present invention is suitable for a case where a flexible substrate having a support layer thickness in the range of 25 to 60 im is used as the substrate.

Other objects, features and benefits of the present invention will become more fully apparent with the following description. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an explanatory diagram for explaining steps in a method of manufacturing an electronic device according to a first embodiment of the present invention.

 FIG. 2 is an explanatory diagram for explaining a step that follows the step shown in FIG. FIG. 3 is an explanatory diagram for explaining a step that follows the step shown in FIG. FIG. 4 is an explanatory diagram for explaining a step that follows the step shown in FIG. FIG. 5 is a characteristic diagram showing a viscosity-temperature curve obtained by measuring the thermosetting resin used in the first embodiment of the present invention with a rheometer.

 FIG. 6 is an explanatory diagram for explaining a method for manufacturing an electronic device according to the second embodiment of the present invention.

 FIG. 7 is an explanatory diagram for describing a method of manufacturing an electronic device according to a third embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

 [First Embodiment]

 FIG. 1 to FIG. 4 are explanatory diagrams for explaining each step in the method for manufacturing an electronic device according to the first embodiment of the present invention. The method for manufacturing an electronic device according to the present embodiment is a method for manufacturing an electronic device including a substrate and electronic components mounted on the substrate. The electronic component is, for example, a semiconductor element.

First, a substrate used in the present embodiment will be described with reference to FIG. The substrate used in the present embodiment has an insulating support layer and a patterned conductor layer disposed so as to be adjacent to at least one surface of the support layer. This embodiment is suitable for a case where a flexible substrate having a support layer thickness in the range of 25 to 60 zm is used as the substrate. In the present embodiment, in particular, a wiring board 10 having a conductor layer 12 patterned according to a predetermined wiring pattern is used as a board. The wiring board 10 includes an insulating support layer 11 and a conductor layer 12 arranged so as to be adjacent to one surface (the upper surface in FIG. 1) 11 a of the support layer 11. have. Here, although not shown in FIG. 1, a conductor layer such as a wiring pattern may be provided on the lower surface of the support layer 11. Of this implementation The support layer 11 in the embodiment is entirely a liquid crystal polymer layer formed of a liquid crystal polymer. The conductor layer 12 has a connection portion 12a connected to the bump of the electronic component.

 As the liquid crystal polymer constituting one layer of the liquid crystal polymer, for example, a liquid crystal polyester with a pick-up opening is used. The thickness of one layer of the liquid crystal polymer is preferably in the range of 20 to 100 im, more preferably in the range of 25 to 50 m. The conductor layer 12 is formed of a metal foil. The metal constituting the metal foil is preferably copper. The thickness of the conductor layer 12 is preferably in the range of 5 to 20 m, and more preferably in the range of 7 to 15 zm.

 The wiring board 10 can be manufactured, for example, as follows. That is, first, a film made of a liquid crystal polymer and a metal foil are thermocompression-bonded. The film made of the liquid crystal polymer becomes the liquid crystal polymer layer, that is, the support layer 11. Next, the conductive layer 12 is formed by etching the metal foil.

 In the method for manufacturing an electronic device according to the present embodiment, as shown in FIG. 1, the wiring substrate 10 is configured such that one surface 11 a of the support layer 11 faces upward and the opposite surface lib Is placed on the support base 30 so that the is in contact with the upper surface of the support base 30. The support 30 has a built-in heater whose temperature can be adjusted. Next, an insulating thermosetting resin 32 before curing is arranged on the wiring board 10 in a region where the electronic component is to be arranged. The arrangement of the thermosetting resin 32 is performed by, for example, applying using a syringe 31. The temperature of the support 30 is higher than room temperature (room temperature), but is controlled so that the thermosetting resin 32 does not cure, for example, a temperature of 50 to 100. . Thus, the wiring board 10 is heated so as to approach the temperature of the support 30. Note that heat is not transmitted instantaneously from the support 30 to the wiring board 10, and the electronic component mounting process in the present embodiment is performed in a short time. Therefore, the temperature of the support 30 and the temperature of the wiring board 10 usually do not match. Therefore, the temperature of the support 30 should be set slightly higher than the curing temperature of the thermosetting resin 32, as long as the thermosetting resin 32 on the wiring board 10 can maintain fluidity. Is also good.

Next, as shown in FIG. 2, the electronic component 21 mounted on the wiring board 10 is held by the heating / pressing tool 40. The electronic component 21 is located on one side 21 a It has a plurality of exposed bumps 22. The connection portion 1 2a of the conductor layer 1 2 and the bump 22 are arranged at positions facing each other when the surface 11a of the support layer 11 and the surface 21a of the electronic component 21 face each other. ing. The bump 22 is, for example, a gold plated pump or a gold stud bump. The bump 22 corresponds to the electrode in the present invention. Although not shown, the heating / pressing tool 40 has a plurality of suction ports on a surface 40 a in contact with the electronic component 21. Inside the heating / pressurizing tool 40, a suction path following the suction port is provided. The suction path is connected to a suction pump. Then, the heating / pressurizing tool 40 sucks the gas in the suction passage by the suction pump, so that the electronic component 21 is adsorbed on the surface 40a so that the electronic component 21 can be held. I have.

 The heating / pressurizing tool 40 has a built-in heater capable of adjusting the temperature. Further, the heating / pressing tool 40 is movable vertically and horizontally, and can apply a load to the held electronic component 21.

 The electronic component 21 is heated by the heating tool 40 so that the surface 21b opposite to the surface 21a is in contact with the surface 40a of the heating and pressing tool 40. 22 is arranged on wiring board 10 so as to face connecting portion 12a.

Next, as shown in FIG. 3, the heating / pressing tool 40 is lowered, and the connection is performed with the thermosetting resin 32 interposed between the wiring board 10 and the electronic component 21. The part 1 2a is brought into contact with the bump 22. In the process of lowering the heating / pressing tool 40, the thermosetting resin 32 spreads and is completely filled between the wiring board 10 and the electronic component 21. Thus, in the present embodiment, the thermosetting resin 32 is interposed between the wiring board 10 and the electronic component 21 so as to cover at least the connection portion 12a, and the bump 22 is connected. Electronic component 21 is arranged on wiring board 10 so as to face portion 12a. Next, the connecting part 12a, the bump 22 and the thermosetting resin 32 are heated by heating the electronic component 21 with the heating / pressing tool 40 so that they reach a predetermined temperature. I do. At the same time, by applying a load to the electronic component 21 by the heating / pressing tool 40, the connecting portion 12a and the bump 22 are pressed so that they come into close contact with each other. The preferred set temperature of the heating and pressing tool 40 is in the range of 200 to 320, and more preferably in the range of 220 to 280. Also, The pressure of the pressure is preferably in the range of ^{4 X 1 0 7 ~ 1 X} 1 0 8 P a, and more preferably in the range of ^{5 XI 0 7 ~8 X 1 0} 7 P a. Hereinafter, this process is referred to as a heating and pressing process.

 In the present embodiment, in the heating and pressurizing step, the connection portion 12a and the bump 22 are thermocompression-bonded to connect them, and the thermosetting resin 32 is heated and cured. As a result, the connection between the connection portion 12a and the bump 22 is sealed. A portion of the thermosetting resin 32 protruding from between the wiring board 10 and the electronic component 21 forms a fillet 33. The time required for the heating / pressurizing step is suitably in the range of 0.1 to 10 seconds, but is more preferably in the range of 0.5 to 3 seconds.

 In addition, the control of the temperature of the connection portion 12a, the bump 22, and the thermosetting resin 32 in the heating / pressing process is performed as follows, for example. That is, the relationship between the temperature of the heating / pressing tool 40 and the temperatures of the connecting portion 12a, the bump 22 and the thermosetting resin 32 is determined in advance by an experiment. The temperature of the connection portion 12 a, the bump 22 and the thermosetting resin 32 is, for example, measured by a temperature sensor inserted in the thermosetting resin 32 at a position between the wiring board 10 and the electronic component 21. To detect. In the actual heating / pressing process, by controlling the temperature of the heating / pressing tool 40 based on the relationship between the temperatures determined as described above, the connection portion 12a, the bump 22 and the thermosetting The temperature of the conductive resin 32 is controlled.

 Next, as shown in FIG. 4, the heating / pressing tool 40 is separated from the electronic component 21 and the heating and pressurizing of the electronic component 21 are stopped. Thereafter, the wiring board 10 and the electronic component 21 are cooled, and the mounting of the electronic component 21 on the wiring board 10 is completed. Thus, an electronic device including the wiring board 10 and the electronic components 21 mounted on the wiring board 10 is completed.

 The temperature of the connecting portion 12a, the bump 22 and the thermosetting resin 32 in the heating / pressing step is preferably in the range of 180 to 280 ° C, and the temperature in the range of 200 to 260 ° C. More preferably, it is within the range.

Further, the thermosetting resin 32 used in the present embodiment is a liquid having a constant low viscosity at room temperature (room temperature). Within this range, those whose viscosity increases with increasing temperature are preferred.

 In particular, in the present embodiment, before the heating / pressing step, the substrate 11 is placed on the support 30 whose temperature is controlled at 50 to 100 ° C., and the thermosetting resin 3 2 is arranged on the surface 11 a of the substrate 11. In this state, the thermosetting resin 32 is preferably a liquid having a viscosity of 1.0 X 10 Pa · s or less. Further, it is preferable that the viscosity of the thermosetting resin 32 rises as the temperature rises in a predetermined temperature range in the heating and pressing steps. The above-mentioned predetermined temperature range is preferably 80 to 130 ° C, more preferably 80 to 120 ° C, and it is in the range of 85 to 115 ° C. Is most preferred.

Here, the viscosity-temperature characteristics of the thermosetting resin 32 used in the present embodiment obtained by measurement with a rheometer will be described in detail. As described above, the thermosetting resin 32 is preferably in a liquid state before the heating / pressing step. For this purpose, the viscosity of the thermosetting resin 32 in the viscosity-temperature curve obtained by measurement with a rheometer at a temperature rising rate of 5 ° CZ minutes indicates that the viscosity of the thermosetting resin 32 is within the temperature range of 50 to 90. It is preferable to exhibit an action of not more than 1.0 X 10 Pa · s in a temperature range having a width of at least 10 ° C. In addition, in the viscosity-temperature curve obtained by the same measurement, the viscosity of the thermosetting resin 32 is 80 to 130 ° C, particularly preferably 80 to 120 ° C, and most preferably 85 to 1100. Within the range of 15 ° C, the temperature rises with the temperature rise, and within the range of the temperature change of 30 ° C or less, from 1.0 X 10 ² Pa's to 1.0 X 10 ⁵ Pa · It is preferable to show a behavior that changes to s. If the temperature variation required to change the viscosity of the thermosetting resin 3 2 'to ^{s 1. 0 X 1 0 5 P} a' 1. 0 X 1 0 2 P a to s is greater than 3 0 ° C, Mounting in a short time may be difficult. Therefore, the above-mentioned temperature change amount is 30 or less, and the smaller, the more preferable. The temperature change amount is preferably in the range of 0.1 to 30, more preferably in the range of 0.1 to 20 and is in the range of 0.1 to 15 Is most preferred.

Further, as the thermosetting resin 32, for example, a resin containing an epoxy-based thermosetting resin or a polyimide-based thermosetting resin can be used. Of these, epoxy-based thermosetting resins are excellent in terms of heat resistance, and therefore, it is particularly preferable to use epoxy-based thermosetting resins as the thermosetting resin 32. When the thermosetting resin 32 contains an epoxy resin, it is preferable to use a liquid epoxy resin at room temperature. Examples of such epoxy resins include bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl ester type epoxy resin and phenol nopolak type epoxy resin. Those containing at least one of the following can be used.

 When the thermosetting resin 32 includes an epoxy resin, the thermosetting resin 32 further includes a latent curing catalyst having a property of rapidly functioning as an epoxy resin curing catalyst at a specific temperature or higher. It is preferred to include. The above-mentioned specific temperature is defined as a temperature within a temperature range where the viscosity of the thermosetting resin 32 increases and the curing reaction is completed (for example, 80 to 280 or 85 to 26 O ^ C). Temperature. Latent curing catalysts include microcapsule type and amine adduct type. Among these, from the viewpoint of mounting performance and stability, it is preferable to use a microcapsule type as the latent curing catalyst.

Here, for one example of the thermosetting resin 32 used in the present embodiment, FIG. 5 shows a viscosity-temperature curve obtained by measurement with a rheometer at a heating rate of 5 ° CZ. This thermosetting resin contains an epoxy resin and a microcapsule-type latent curing catalyst. In the viscosity-temperature curve shown in FIG. 5, the viscosity of the thermosetting resin 32 is 1.0 X 10 Pa in a temperature range of at least 1 Ot in the temperature range of 50 to 90. · Low viscosity below s. Further, in the viscosity-temperature curve shown in FIG. 5, the viscosity of the thermosetting resin 32 sharply rises with the temperature rise in the range of 80 to 130 ° C. Further, in the viscosity first temperature curve shown in FIG. 5, the viscosity of the thermosetting resin 3 2 changes to ^{1. 0 X 1 0 2 P a} 's or al ^{1. 0 X 1 0 5 P a} · s The temperature change required for this is in the range of 0.1 to 15 ° C.

As described above, in the present embodiment, in the heating / pressing step, the connection between the connection portion 12 a of the conductor layer 12 on the wiring board 10 and the bump 22 of the electronic component 21 by thermocompression bonding is performed. The sealing of the connection between the connection portion 12a and the bump 22 with the thermosetting resin 32 is performed collectively and almost simultaneously. Therefore, according to the present embodiment, Since the connecting portion 12a and the bump 22 are directly connected, and the connecting portion of both is reinforced by the thermosetting resin 32, the electrical connection of the connecting portion 12a and the bump 22 is made. The characteristics are improved. Further, according to the present embodiment, the displacement of the connection portion between the connection portion 12a and the bump 22 can be suppressed until the sealing is completed after the connection portion 12a and the bump 22 contact. Therefore, the reliability of this connection is high.

 Further, according to the present embodiment, the connecting portion 12a and the bump 22 are directly connected without using a conductive material having fluidity such as a conductive paste or a solder paste. Therefore, it is possible to prevent the occurrence of current leakage between adjacent electrodes and conductor layers, thereby making it possible to cope with a narrow pitch of the electrodes and conductor layers. Also, in the present embodiment, the connection between the connection portion 12a and the bump 22 and the sealing of the connection portion between the connection portion 12a and the bump 22 are collectively and almost simultaneously performed. Therefore, according to the present embodiment, electronic component 21 can be mounted on wiring board 10 in a short time.

 In the present embodiment, the entire support layer 11 of the wiring board 10 is a liquid crystal polymer layer. Liquid crystal polymers have extremely low hygroscopicity compared to polyimide resins and glass epoxies. Specifically, the water absorption of the resin layer measured in accordance with the standard IPC-TM650 2.6.2 when immersed in water for 24 hours is 3.2% in the case of polyimide resin, In the case of a liquid crystal polymer, the value is as low as 0.04%.

 Therefore, the support layer 11 contains almost no moisture before the heating / pressing step. Therefore, in the present embodiment, even if heat is applied to the wiring board 10 in the heating / pressurizing step, moisture hardly evaporates from the wiring board 10, and the moisture hardens in the thermosetting resin 32. Almost no air bubbles are mixed. As a result, according to the present embodiment, it is possible to prevent the occurrence of voids in the sealed portion made of the thermosetting resin 32 after curing.

 Further, in the present embodiment, since the water hardly evaporates from the wiring board 10, it is considered that the amount of heat consumed for evaporating the water reduces the curing rate of the thermosetting resin 32. Can be prevented.

Further, in the present embodiment, almost no water evaporates from the wiring board 10. Therefore, it is possible to prevent a decrease in the curing rate of the thermosetting resin 32 due to diffusion of water molecules into the thermosetting resin 32 before curing.

 The thermal conductivity of the liquid crystal polymer layer is larger than that of the support layer made of polyimide resin or glass epoxy, and smaller than that of the support layer made of an inorganic material such as ceramic. Specifically, the thermal conductivity of polyimide resin is 0.2 WZm and that of ceramic is 15 to 25 W / m ° C, whereas that of liquid crystal polymer is Indicates a value of 0.5 WZmt. This thermal conductivity can be measured by the disc heat flow meter method (also called the protective heat flow meter method or the steady-state comparison method) shown in the standard ASTMEl530. In this method, the heater and the reference calorimeter are brought into close contact with each other in a steady state with a temperature difference of about 30 K above and below the specimen, and the temperature difference between both ends of the specimen and the output of the reference calorimeter are measured. Is a method of obtaining the thermal conductivity from

 Therefore, in the present embodiment, even when the thermosetting resin 32 is heated by heating the electronic component 21, the thermosetting resin 32 is located at a position away from the electronic component 21. It is easy for enough heat to be transmitted to the parts located in the area. Therefore, according to the present embodiment, it is possible to prevent the curing rate of a portion of thermosetting resin 32 arranged at a position distant from electronic component 21 from decreasing.

 Further, according to the present embodiment, even when a plurality of electronic components are mounted on the same wiring board, the heat applied to the place where the electronic components are mounted is transmitted via the support layer. It can be prevented that the heat is transmitted to the thermosetting resin in other places and the curing reaction of the resin starts. From this point, in the present embodiment, it is preferable to use a liquid crystal polymer layer having a thermal conductivity in the range of 0.3 to 1 WZm ° C.

Further, it is assumed that the liquid crystal polymer layer has a property that the thermal conductivity in a direction parallel to the plane is larger than the thermal conductivity in a direction perpendicular to the plane. Therefore, according to the present embodiment, in the heating / pressing step, the support layer 11 does not dissipate much heat and the thermosetting resin 3 2 of the surface 11 a of the support layer 11 The temperature of the portion in contact with the surface can be quickly raised and made uniform. As a result, according to the present embodiment, it is possible to quickly and satisfactorily seal with thermosetting resin 32. Further, in the present embodiment, a thermosetting resin 32 is used in which the curing reaction is completed quickly at a relatively low temperature. Therefore, according to the present embodiment, the electronic component 21 can be mounted on the wiring board 10 in a short time without damaging the liquid crystal polymer layer.

 [Second embodiment]

 Next, a method for manufacturing an electronic device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 shows a completed electronic device manufactured by the manufacturing method according to the present embodiment. In the present embodiment, a wiring board 50 is used instead of the wiring board 10 in the first embodiment. The wiring board 50 includes an insulating support layer 51 and a conductor layer 12 arranged so as to be adjacent to one surface (the upper surface in FIG. 6) 51 a of the support layer 51. Have. The support layer 51 in the present embodiment has a first layer 52 disposed on the upper side in FIG. 6 so as to be adjacent to the conductor layer 12 and a lower surface of the first layer 52. And a second layer 53 joined thereto. The first layer 52 is a liquid crystal polymer layer. The second layer 53 is a resin layer formed of a polyimide resin or the like.

The material and thickness of the liquid crystal polymer layer forming the first layer 52 are the same as those of the liquid crystal polymer layer forming the support layer 11 in the first embodiment. However, in the present embodiment, since the support layer 51 is composed of two different insulating layers, the thickness of the liquid crystal polymer layer is about half the thickness shown in the first embodiment. Is preferred. Also, the material and thickness of the conductor layer 1 2 Ru similar der conductor layers 1 2 of the first embodiment ₉

 The second layer 53 preferably has a lower thermal conductivity, a higher hardness and a higher melting point than the first layer 52. The thickness of the second layer 53 is arbitrary.

The wiring board 50 in the present embodiment can be manufactured, for example, as follows. That is, first, the liquid crystal polymer film and the metal foil are thermocompression-bonded. The liquid crystal polymer film becomes the first layer 52. Next, a thermocompression-bondable resin film such as a thermoplastic polyimide film is thermocompression-bonded to the surface of the liquid crystal polymer film opposite to the surface to which the metal foil is bonded. This resin film becomes the second layer 53. Next, the conductor layer 12 is formed by etching the metal foil. In addition, liquid crystal poly In both cases of thermocompression bonding of the polymer film and the metal foil and thermocompression bonding of the resin film to the liquid crystal polymer film, the temperature of the liquid crystal polymer film is lower than the melting point of the liquid crystal polymer, that is, about 280. Must be kept below.

 Further, wiring board 50 in the present embodiment may be manufactured as follows. That is, first, a liquid crystal polymer film and a metal foil are thermocompression-bonded to form a laminate. The liquid crystal polymer film becomes the first layer 52. Next, the above-mentioned laminated body is placed on a table so that the metal foil faces down. Next, a resin such as a polyimide resin for forming the second layer 53 or a solution of a precursor resin of the resin is applied to form a resin layer. Next, the solvent in the resin layer is removed, and the resin layer is dried. This resin layer becomes the second layer 53. Next, the conductor layer 12 is formed by etching the metal foil. When the liquid crystal polymer film and the metal foil are thermocompression-bonded, the temperature of the liquid crystal polymer film must be kept below the melting point of the liquid crystal polymer, that is, below about 280 ° C.

 In the present embodiment, of the first layer 52 and the second layer 53 constituting the support layer 51 of the wiring board 50, only the first layer 52 adjacent to the conductor layer 12 is used as the liquid crystal polymer layer. I have. Therefore, according to the present embodiment, the thermal conductivity of second layer 53 can be made smaller than the thermal conductivity of first layer 52. Thus, according to the present embodiment, in the heating / pressing step, the second layer 53 can prevent heat from escaping from the support layer 51. Therefore, according to the present embodiment, it is possible to effectively raise the temperature of the portion of the surface 5 la of the support layer 51 that is in contact with the thermosetting resin 32 quickly and to make the temperature uniform. it can.

 Further, according to the present embodiment, by using a material having a higher hardness than the first layer 52 as the second layer 53, compared to a case where the entire support layer is a liquid crystal polymer layer, The strength of the support layer 51 can be increased.

 Further, according to the present embodiment, since second layer 53 does not touch thermosetting resin 32, there is no problem even if second layer 53 has large hygroscopicity.

 Other configurations, operations, and effects of the present embodiment are the same as those of the first embodiment.

[Third embodiment] Next, a method of manufacturing an electronic device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a completed electronic device manufactured by the manufacturing method according to the present embodiment. In the present embodiment, a wiring board 60 is used instead of the wiring board 10 in the first embodiment. The wiring board 60 includes an insulating support layer 61 and a conductor layer 12 disposed adjacent to one surface (the upper surface in FIG. 7) 61 a of the support layer 61. Have. The support layer 61 according to the present embodiment has a first layer 62 and a second layer 63. The first layer 62 is a liquid crystal polymer layer. The second layer 63 has a concave portion 64 that accommodates the first layer 62. The first layer 62 is housed in the recess 64. The upper surface of the first layer 62 and the upper surface of the second layer 63 other than the concave portion 64 form one plane, and this plane is one surface 61 a of the support layer 61 . The second layer 63 is a resin layer formed of a polyimide resin or the like.

 The first layer 62 is arranged so as to be adjacent to at least the connection portion 12a of the conductor layer 12. In the present embodiment, in particular, the first layer 62 is arranged so as to be adjacent to the conductor layer 12 at least in a region facing the electronic component 21. It is preferable that the first layer 62 is disposed adjacent to the conductor layer 12 at least in a region where the cured thermosetting resin 32 is disposed.

 The material and thickness of one layer of the liquid crystal polymer forming the first layer 62 are the same as those of the liquid crystal polymer layer forming the support layer 11 in the first embodiment. However, in the present embodiment, since the support layer 61 is composed of two different insulating layers, the thickness of the liquid crystal polymer layer is about half the thickness shown in the first embodiment. Is preferred. The material and thickness of the conductor layer 12 are the same as those of the conductor layer 12 in the first embodiment.

 The second layer 63 preferably has a lower thermal conductivity, a higher hardness, and a higher melting point than the first layer 62. The thickness of the second layer 63 is arbitrary.

The wiring board 60 in the present embodiment can be manufactured, for example, as follows. That is, first, a liquid crystal polymer film is arranged in a frame having a size approximately equal to the size of the wiring board 60 to be manufactured. Next, a resin for forming the second layer 63, such as a polyimide resin, covers the liquid crystal polymer film. Alternatively, a solution of a precursor resin of the resin is filled in the frame to form a resin layer. Next, the solvent in the resin layer is removed, and the resin layer is dried. As a result, a composite of the liquid crystal polymer film and the resin layer is formed. The liquid crystal polymer film becomes the first layer 62, and the resin layer becomes the second layer 63. Next, in the above composite, a metal foil is thermocompression-bonded to the surface where the first layer 62 is exposed. Next, the metal foil is etched to form the conductor layer 12. When the metal foil is thermocompression-bonded to the composite, the temperature of the liquid crystal polymer film must be maintained at a temperature lower than the melting point of the liquid crystal polymer, that is, about 280 ° C. or lower.

 Further, wiring board 60 in the present embodiment may be manufactured as follows. That is, first, a part of one surface of the resin film is etched to form a concave portion 64 having a size approximately equal to the size of the first layer 62 to be formed. Next, a liquid crystal polymer film having a size similar to the size of the concave portion 64 is accommodated in the concave portion 64, and a resin film and a liquid crystal polymer film are thermocompression-bonded to each other. Form. The liquid crystal polymer film becomes the first layer 62 and the resin film becomes the second layer 63. Next, a metal foil is thermocompression-bonded to the surface of the composite where the first layer 62 is exposed. Next, the conductor layer 12 is formed by etching the metal foil. In both cases of thermocompression bonding between the resin film and the liquid crystal polymer film and thermocompression bonding of the metal foil to the composite, the temperature of the liquid crystal polymer film is lower than the melting point of the liquid crystal polymer, that is, about It must be kept below at 280.

 Other configurations, operations, and effects of the present embodiment are the same as those of the second embodiment.

 It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the heating / pressing step, at least one of the connection portion 12a and the bump 22 may be heated to a predetermined temperature. Therefore, in the heating and pressing step, the wiring board 10 may be heated to a predetermined temperature instead of heating the electronic component 21 to a predetermined temperature.

 [Example]

 Hereinafter, examples of the first embodiment will be described, but the present invention is not limited to the following examples.

In this example, first, a 50-zm-thick liquid crystal polymer layer (thermal conductivity 0.5 WZ A wiring board 10 was prepared in which a wiring pattern of a conductor layer 12 having a thickness of 18 m was formed on a support layer 11 made of m ° C). Next, the wiring board 10 was placed on a support 30 heated at 80, and about 10 mg of an epoxy-based thermosetting resin 32 was arranged at a connection portion on the wiring board 10. Here, the epoxy resin-based thermosetting resin contains epoxy resin as a main component and a latent curing catalyst, and has a viscosity measured by a rheometer with a heating rate of 5 ° CZ. The one whose temperature curve is shown in Fig. 5 was used. Then, from the top, the semiconductor device with bumps held by the heat and pressure tool 4 0 (vertical 1 0 mm, lateral 1 0 mm, a thickness of 0. 4 mm) to ^{6. 2 5 X 1 0 7} P a Pressure for 3 seconds. At this time, the temperature of the tool 40 was set to 280. The thermosetting resin 32 started to flow by heat and pressure, formed a fillet, and was cured. After the heating and pressurizing steps, the tool 40 was separated from the semiconductor element, and the manufacturing process of the electronic device was completed. In the obtained electronic device, as a result of observation by a cross-sectional photograph, the bump and the conductor layer were stably connected, and no generation of voids or the like was observed in the insulating resin layer.

 As described above, in the method for manufacturing an electronic device according to the present invention, as the substrate, the liquid crystal polymer layer in which the support layer is disposed adjacent to at least the connection portion of the conductor layer connected to the electrode of the electronic component is used. A substrate including the same is used. In the method of manufacturing an electronic device according to the present invention, an insulating thermosetting resin before curing is interposed between the substrate and the electronic component, and the electronic component is placed on the substrate so that the electrode faces the connection portion. Then, the connection part and the electrode are brought into contact with each other, and the connection part and the electrode are connected to each other by pressing the connection part and the electrode so that they are in close contact with each other and heating the thermosetting resin. And harden the thermosetting resin. Thus, according to the present invention, it is possible to improve the electrical characteristics and reliability of the connection portion between the electrode of the electronic component and the conductor layer of the substrate, and to prevent the occurrence of a defect in the sealing resin. it can.

 Further, in the present invention, when a thermosetting resin that can complete the curing reaction quickly at a relatively low temperature is used, the mounting of the electronic component on the substrate can be shortened without damaging the liquid crystal polymer layer. Can be done in time.

Based on the above description, it is apparent that various aspects and modifications of the present invention can be implemented. Therefore, within the scope of the following claims, The present invention can be practiced in modes other than the embodiments.

Claims

The scope of the claims 1. A substrate, comprising: an electronic component mounted on the substrate; the substrate comprising: an insulating support layer; and a patterned conductor arranged to be adjacent to at least one surface of the support layer. A method for manufacturing an electronic device, comprising: an electrode connected to the conductor layer;  As the substrate, a substrate including a liquid crystal polymer layer arranged so that the support layer is adjacent to at least a connection portion of the conductor layer connected to an electrode of the electronic component is used, and the substrate and the electron Arranging the electronic component on the substrate with an insulating thermosetting resin before curing interposed between the component and the component such that the electrode faces the connection portion;  The connection portion and the electrode are brought into contact with each other, and the connection portion and the electrode are pressurized so that they are in close contact with each other, and the thermosetting resin is heated. Curing the conductive resin and A method for manufacturing an electronic device, comprising: 2. The thermosetting resin contains an epoxy resin and a latent curing catalyst, and has a viscosity-temperature curve obtained by measurement with a rheometer at a heating rate of 5 minutes. Is less than 1.0X10Pas in the temperature range of at least 10 ° C in the temperature range of 50 to 90 ° C, and the temperature range is 80 to 130 ° C. The temperature rises as the temperature rises, and changes from 1.0 X 10 ² Pa's to 1.0 X 10 ⁵ Pa's within a temperature change range of 30 ° C or less. 2. The method for manufacturing an electronic device according to claim 1, wherein the electronic device has a behavior. , 3. The method according to claim 1, wherein the thermal conductivity of the liquid crystal polymer layer is in a range of 0.3 to 1 WZm.  4. The method according to claim 1, wherein a flexible substrate having a thickness of the support layer in the range of 25 to 60 / im is used as the substrate.