Electronic component-containing module

Abstract

An electronic component-containing module includes a board, electronic components, and a sealing resin and includes a space provided between the board and at least one of the electronic components. The dryness factor of the sealing resin is about 60% or more where, after the electronic component-containing module is moisturized, the electronic component-containing module is heated to the re-melting temperature of a brazing filler metal.

Claims

1. An electronic component-containing module comprising: a board; land electrodes provided on at least one principal surface of the board; an electronic component that includes terminal electrodes and is mounted on the at least one principal surface of the board such that the terminal electrodes are fixed to the land electrodes with a brazing filler metal; and a sealing resin provided on the at least one principal surface of the board to cover the electronic component; wherein the electronic component-containing module includes a space provided between the board and the electronic component; where after the electronic component-containing module is moisturized, the electronic component-containing module is heated to the re-melting temperature of the brazing filler metal, a dryness factor of the sealing resin is about 60% or more; and the dryness factor of the sealing resin is determined by ((W2W3)/(W2W1))100(%), wherein W1 is a mass of a sample of the sealing resin before the electronic component-containing module is moisturized, W2 is a mass of the sample of the sealing resin after the electronic component-containing module is moisturized, and W3 is a mass of the sample of the sealing resin after being heated to the re-melting temperature.

2. The electronic component-containing module according to claim 1, wherein the brazing filler metal is solder.

3. The electronic component-containing module according to claim 1, wherein the electronic component is at least one of a capacitor element, a coil element, a resistance element, a piezoelectric element, a semiconductor element, and an integrated circuit element.

4. The electronic component-containing module according to claim 1, wherein the electronic component and the board are covered by a film and the film is covered by the sealing resin.

5. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler, and a content of the filler in the sealing resin is about 84% by weight or more.

6. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler, and the filler has a particle size of about 100 m or more.

7. The electronic component-containing module according to claim 1, wherein the board is made of resin or ceramic.

8. The electronic component-containing module according to claim 1, wherein the board has a multilayer structure.

9. The electronic component-containing module according to claim 1, wherein the land electrodes are made of copper or aluminum.

10. The electronic component-containing module according to claim 1, wherein a plurality of the electronic components are mounted on the land electrodes.

11. The electronic component-containing module according to claim 1, wherein the sealing resin is a curable resin.

12. The electronic component-containing module according to claim 11, wherein the curable resin is one of an epoxy resin or a polyimide resin.

13. The electronic component-containing module according to claim 1, wherein the sealing resin is a thermoplastic resin.

14. The electronic component-containing module according to claim 13, wherein the thermoplastic resin is polyphenylene sulfide.

15. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler; a content of the filler in the sealing resin is about 84% by weight or more; and the sealing resin is porous.

16. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler; a content of the filler in the sealing resin is about 84% by weight or more; and the filler is made of SiO.sub.2.

17. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler; the filler has a particle size of about 100 m or more; and the sealing resin is porous.

18. The electronic component-containing module according to claim 1, wherein the sealing resin includes a filler; the filler has a particle size of about 100 m or more; and the filler is made of SiO.sub.2.

19. An electronic component-containing module comprising: a board; land electrodes provided on at least one principal surface of the board; an electronic component that includes terminal electrodes and is mounted on the at least one principal surface of the board such that the terminal electrodes are fixed to the land electrodes with a brazing filler metal; and a sealing resin provided on the at least one principal surface of the board to cover the electronic component; wherein the electronic component-containing module includes a space provided between the board and the electronic component; where after the electronic component-containing module is moisturized, the electronic component-containing module is heated to the re-melting temperature of the brazing filler metal, a dryness factor of the sealing resin is about 60% or more; the dryness factor of the sealing resin is determined by ((W2W3)/(W2W1))100(%), wherein W1 is a mass of a sample of the sealing resin before the electronic component-containing module is moisturized, W2 is a mass of the sample of the sealing resin after the electronic component-containing module is moisturized, and W3 is a mass of the sample of the sealing resin after being heated to the re-melting temperature; and the sealing resin includes a filler that is made of SiO.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an exploded plan view of an electronic component-containing module 100 according to a preferred embodiment of the present invention. FIG. 1 shows the inside of the electronic component-containing module 100 separated from a film 6 and a sealing resin 7.

(2) FIGS. 2A, 2B, and 2C are substantial sectional views of the electronic component-containing module 100, FIG. 2A shows an X-X portion in FIG. 1, and FIGS. 2B and 2C show a Y-Y portion in FIG. 1.

(3) FIGS. 3A and 3B are perspective views showing steps performed in an example of a method for manufacturing the electronic component-containing module 100.

(4) FIGS. 4A and 4B are subsequent to FIG. 3B and are perspective views showing steps performed in an example of the method for manufacturing the electronic component-containing module 100.

(5) FIGS. 5A and 5B are substantial sectional views of an electronic component-containing module 200 according to a modification of a preferred embodiment of the present invention.

(6) FIG. 6 is a sectional view of a conventional electronic component-containing module 300 disclosed in Japanese Unexamined Patent Application Publication No. 2011-219726.

(7) FIG. 7 is a sectional view of a conventional electronic component-containing module 400 disclosed in Japanese Unexamined Patent Application Publication No. 2005-302835.

(8) FIGS. 8A and 8B are substantial sectional views showing a state in which a liquid component included in a sealing resin is evaporated by heating to produce gas and therefore terminal electrodes of an electronic component are electrically shorted when a conventional electronic component-containing module 500 is soldered to a board or other substrate of an electronic device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) Preferred embodiments of the present invention are described below with reference to drawings.

(10) FIGS. 1, 2A, and 2B show an electronic component-containing module 100 according to a preferred embodiment of the present invention. FIG. 1 is an exploded plan view and shows the inside of the electronic component-containing module 100 separated from a sealing resin 7 below. FIGS. 2A and 2B are substantial sectional views. FIG. 2A corresponds to an X-X portion in FIG. 1. FIG. 2B corresponds to a Y-Y portion in FIG. 1.

(11) The electronic component-containing module 100 includes a board 1. The board 1 is preferably made of, for example, resin, ceramic, or other suitable material. The board 1 may have a multilayer structure as shown, for example, in FIG. 2C. The board 1 may contain an electronic component.

(12) Land electrodes 2 are provided on a principal surface of the board 1. The land electrodes 2 are made of an arbitrary material such as, for example, copper or aluminum. Wiring electrodes, which are not shown, connecting the land electrodes 2 by being provided on a principal surface of the board 1.

(13) The following components are mounted on the board 1 using the land electrodes 2: electronic components 3 each including terminal electrodes 3a provided at both ends of a component body and an electronic component 4 including a plurality of flip chip electrodes (not shown) provided on the bottom surface of a component body. In particular, the terminal electrodes 3a of the electronic components 3 and the flip chip electrodes of the electronic component 4 are fixed to the land electrodes 2 with a brazing filler metal, for example, solder 5.

(14) The sealing resin 7 is structured so as to cover the electronic components 3 and 4, which are mounted on the board 1.

(15) When the sealing resin 7 is a curable resin, the sealing resin 7 is provided on the electronic components 3 and 4 in a semi-molten state and is then cured. A space S1 is provided between the board 1 and each of the electronic components 3 and 4. The space S1 may be formed such that when the semi-molten sealing resin 7 is provided, the temperature or melting condition of the sealing resin 7, the magnitude of the pressure pressing the sealing resin 7 in a direction of the board 1, the rate of pressing the sealing resin 7, and/or other conditions may be adjusted.

(16) The sealing resin 7 is preferably a resin with a dryness factor of about 60% or more, for example. A method for measuring the dryness factor is described above. The sealing resin 7 is an arbitrary material and may be, for example, a curable resin, such as an epoxy resin or a polyimide resin.

(17) The sealing resin 7 preferably contains a filler. The content of the filler in the sealing resin 7 is preferably about 84% by weight or more, for example. This is to provide a sealing resin 7 that is porous and has an increased dryness factor.

(18) The filler preferably has a maximum particle size of about 100 m or more, for example. This is also to provide a sealing resin 7 that is porous and has an increased dryness factor.

(19) Since the sealing resin 7 is a resin with a dryness factor of about 60% or more, the volume of gas produced by the evaporation of a liquid component included in the sealing resin 7 is small even though the electronic component-containing module 100 is heated when the electronic component-containing module 100 is mounted on a board or other substrate of an electronic device using solder or other bonding material. Therefore, in an inner portion thereof, no solder flash occurs or no electrical shorting or electrical discontinuity occurs.

(20) Before the electronic component-containing module 100 is used, the liquid component remains in the sealing resin 7 or the sealing resin 7 absorbs the liquid component during manufacture or storage. Even if the liquid component remains in the sealing resin 7 during manufacture or the sealing resin 7 absorbs the liquid component during storage, no electrical shorting or electrical discontinuity occurs in an inner portion when the electronic component-containing module 100 according to a preferred embodiment is soldered to a board or other substrate of an electronic device.

(21) The electronic component-containing module 100 according to a preferred embodiment can be manufactured through, for example, steps shown in FIGS. 3A, 3B, 4A, and 4B so.

(22) First, as shown in FIG. 3A, the land electrodes 2 are formed on the board 1. The land electrodes 2 can be formed such that, for example, copper foil is attached over a principal surface of the board 1 and is etched into a desired shape.

(23) Next, as shown in FIG. 3B, a solder paste 5 is applied to the land electrodes 2 and the electronic components 3, which include the terminal electrodes 3a formed at both ends of the component body, are then preliminarily fixed on the land electrodes 2. Likewise, the electronic component 4, which includes the flip chip electrodes formed on the bottom surface of the component body, is preliminarily fixed on the land electrodes 2 having the solder paste 5 applied thereto, which is not shown.

(24) Next, as shown in FIG. 4A, the solder paste 5 is melted and is subsequently solidified by cooling, such that the terminal electrodes 3a of the electronic components 3 are fixed to the land electrodes 2 with the solder 5. Likewise, the flip chip electrodes of the electronic component 4 are fixed to the land electrodes 2 with the solder 5, which is not shown.

(25) Next, as shown in FIG. 4B, the board 1 and the electronic components 3 and 4, which are mounted on the board 1, are covered with the sealing resin 7, such that the electronic component-containing module 100 according to a preferred embodiment of the present invention is produced. When the sealing resin 7 is, for example, a curable resin, a step of covering the electronic components 3 and 4 with the sealing resin 7 is performed such that the semi-molten sealing resin 7 is provided on the electronic components 3 and 4, the lower surface thereof is deformed to follow the shapes of the electronic components 3 and 4, the upper surface thereof is flattened, and the sealing resin 7 is then cured by a process, such as heat curing or light curing, for example.

(26) The structure of the electronic component-containing module 100 according to a preferred embodiment of the present invention and an example of the method for manufacturing the same have been described above. However, contents of the present invention are not limited to these. Various modifications can be made without departing from the spirit of the present invention.

(27) As shown in FIGS. 5A and 5B, in an electronic component-containing module 200 according to a modification of a preferred embodiment of the present invention, for example, a film 6 may be interposed between a board 1, electronic components 3 and 4 mounted on the board 1, and a sealing resin 7. The materials used for the film 6 are not particularly limited, and may be made of, for example, a curable resin such as an epoxy resin or a polyimide resin or a thermoplastic resin such as polyphenylene sulfide. The film 6 may have a single-layer structure or a multilayer structure including a plurality of layers.

(28) The film 6 can be structured such that the curable resin is attached over the board 1 and the electronic components 3 and 4, which are mounted on the board 1, by, for example, a process, such as vacuum laminating, rubber pressing, or isostatic pressing, capable of following a complicated surface shape and is subsequently cured by a process, such as heat curing or light curing.

(29) Where the film 6 is interposed between the board 1, the electronic components 3 and 4, which are mounted on the board 1, and the sealing resin 7, the sealing resin 7 does not flow therebetween during manufacture and, therefore, spaces S1 are readily provided between the board 1 and the electronic components 3 and 4.

(30) In order to confirm the effectiveness of preferred embodiments of the present invention, experiments below were performed. First, 222 samples according to each of Examples 1 and 2 and Comparative Examples 1 and 2 were prepared.

(31) Each sample has a structure in which an electronic component 3-mounted portion is extracted from the electronic component-containing module 100, according to a preferred embodiment of the present invention, shown in FIGS. 2A and 2B. That is, in the sample, terminal electrodes 3a of an electronic component 3 are fixed to land electrodes 2 provided on a board 1 with solder 5. The electronic component 3 is covered by a film 6. Furthermore, the film 6 is covered by a sealing resin 7. Thus, the sample includes a single electronic component. A space S1 is provided between the board 1 and the electronic component 3.

(32) The distance between a pair of the land electrodes 2 formed on the board 1 was about 0.2 mm.

(33) The electronic component 3 was an SMD component having a height of about 0.3 mm, a width of about 0.3 mm, and a length of about 0.6 mm.

(34) The solder 5 was one having a re-melting temperature of about 220 C.

(35) The film 6 had a thickness of about 20 m and was made of an epoxy resin with a dryness factor of about 85%.

(36) The sealing resin 7 was an epoxy resin including a filler made of SiO.sub.2 and was varied in dryness factor in Examples 1 and 2 and Comparative Examples 1 and 2. The dryness factor was adjusted by varying the content of the filler or the maximum particle size of the filler. The thickness of the sealing resin 7 was constant at about 0.75 mm, in Examples 1 and 2 and Comparative Examples 1 and 2.

(37) The dryness factor of the sealing resin 7 was about 85% in Example 1, about 60% in Example 2, about 58% in Comparative Example 1, and about 38% in Comparative Example 2.

(38) Table 1 shows the number of samples in which solder flash occurred among the 222 samples. The occurrence of solder flash was confirmed by disassembling each sample.

(39) TABLE-US-00001 TABLE 1 Compar- Compar- Example Example ative ative Sample 1 2 Example 1 Example 2 Solder flash 85% 60% 58% 38% Number of 0 0 14 84 samples in which solder flash occurred (among 222 samples)

(40) In Examples 1 and 2, no solder flash occurred. However, in Comparative Example 1, solder flash occurred in 14 of the 222 samples and in Comparative Example 2, solder flash occurred in 84 of the 222 samples.

(41) From the above, it is clear that preferred embodiments of the present invention are effective in preventing solder flash from occurring in an inner portion and in preventing electrical shorting or electrical discontinuity from occurring even though an electronic component-containing module is heated when the electronic component-containing module is mounted on a board or other substrate of an electronic device using solder or other substrate.

(42) While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.