Module including elastic wave device

Abstract

The invention discloses a module containing an elastic wave device, which comprises two or more electronic devices mounted on a module substrate, and a part of the electronic devices are used as device chips with functions of the elastic wave device; one surface of the device chip comprises a functional element of an IDT electrode and a salient point connected to the functional element, and a gap is formed between one surface of the device chip and the mounting surface of the module substrate by using the salient point, so that the device chip is mounted on the module substrate; the module substrate is provided with a solder mask, and the solder mask is used for covering an area needing to be covered on the mounting surface; forming a blank area without the solder mask layer in the solder mask layer below one surface of the device chip; and the solder mask layer forms two or more channels near the blank area. By means of the channel, scaling powder residues and the like in the blank area can be effectively cleaned after the device chip is installed.

Description

Technical Field

[0001] The present invention relates to an improvement of a module, in which a part of two or more electronic devices mounted on a module substrate serves as a device chip having a function of a surface acoustic wave device. Background Art

[0002] In a conventional module, a part of two or more electronic devices mounted on a module substrate serves as a device chip having a function of a surface acoustic wave device. Figure 10 The main part thereof is shown.

[0003] The device chip 100 includes, on one surface thereof, a functional element 101 including an IDT electrode, and bumps 102 made of solder connected to the functional element 101 through wirings.

[0004] On the other hand, a region to be covered on the electronic device mounting surface of the module substrate 200 is covered with a solder resist layer 300.

[0005] A region on the mounting surface for mounting the device chip 100 is a blank region 301 without the solder resist layer 300. In the blank region 301, bump pads 201 corresponding to the bumps 102 are provided on the mounting surface.

[0006] The device chip 100 is mounted on the module substrate 200 in a state where the bumps 102 are fixed to the bump pads 201 by reflow soldering or the like, and a dimensional gap in which the bumps 102 protrude is left between the one surface and the mounting surface located in the blank region 301.

[0007] A sealing resin 400 is formed on the mounting surface of the device chip 100 so that the gap becomes an internal space. The functional element 101 of the device chip 100 is located in the internal space, thereby functioning as a surface acoustic wave device.

[0008] However, after the device chip 100 is mounted on the blank region 301, it is necessary to clean flux residues and the like.

[0009] Therefore, for such a module, it is necessary to appropriately provide a structure capable of efficiently performing such cleaning.

[0010] At this time, as Figure 10 shown, compared with the case where the opening edge 301a of the blank region 301 is located on the center side of the device chip 100 with respect to the outer edge 103 of one surface of the device chip 100, as Figure 11As shown, when the opening edge 301a of the blank area 301 is located outside the outer edge 103 of one side of the device chip 100, since the distance L between the outer edge 103 and the opening edge 301a can be increased, therefore Figure 11 the structure shown is more suitable for improving the cleaning efficiency.

[0011] However, in such a module, in order to ensure the formation of the internal space, usually before forming the sealing resin 400, a method of covering the device chip 100 with a thin film 500 used together with the module substrate 200 is adopted.

[0012] This thin film 500 is usually covered on the device chip 100 in a vacuum environment after the device chip 100 is installed, and then the air pressure in the space above the thin film 500 is increased to make it closely fit on the device chip 100 and the module substrate 200.

[0013] However, when simply adopting Figure 11 the structure shown, when the thin film 500 is sealed as described above, the thin film 500 is largely pulled into the blank area 301, and it is expected that the pulled part will be damaged. Summary of the Invention

[0014] The main problem to be solved by the present invention is to provide a structure for effectively cleaning flux residues and the like in the blank area after the device chip is installed for such a module.

[0015] To solve the above problems, the present invention provides a module including an elastic wave device, the module includes two or more electronic devices installed on a module substrate, and some of the electronic devices are device chips having the function of an elastic wave device; one side of the device chip includes a functional element of an IDT electrode and bumps connected to the functional element, and a gap is formed between one side of the device chip and the mounting surface of the module substrate by using the bumps; the module substrate has a solder mask layer, and the solder mask layer is used to cover the areas to be covered on the mounting surface; a blank area without a solder mask layer is formed in the solder mask layer below one side of the device chip; two or more channels are formed in the solder mask layer near the blank area, including the following two positions, the first position is below one side of the device chip; the second position is outside the side of the device chip having a thickness and not below one side of the device chip.

[0016] One outer edge of one side of the device chip is in contact with the side surface, and at any position around the center of the device chip, when observing the device chip in a direction perpendicular to the one side, the opening edge of the blank area overlaps with the outer edge, or the opening edge is located on the center side of the device chip relative to the outer edge within a range of 20 to 50 μm.

[0017] In addition, the channel is a groove-like structure.

[0018] Furthermore, as an embodiment of the present invention, the module including the elastic wave device further includes a thin film covering the module substrate and the device chip, and a sealing resin formed on the thin film.

[0019] In this case, the distance between one side of the device chip and the surface of the solder resist layer can also be set to a size less than 1.5 times the thickness of the thin film in a direction perpendicular to one side of the device chip. Further, the thickness of the thin film is 20 to 50 μm; the size of the distance is 30 to 75 μm.

[0020] In addition, the channel is a groove-like structure; it further includes a thin film covering the device chip and the module substrate, and a sealing resin formed on the thin film; the groove width size of the channel is less than 1.5 times the thickness of the thin film. In this case, the groove width range of the channel is 30 to 75 μm; the thickness of the thin film is 20 to 50 μm.

[0021] In addition, the length of the channel is 100 μm or more, and the length of the part below one side of the device chip is 20 to 50 μm.

[0022] As an embodiment of the present invention, the channel communicates with the blank area; the contour of the opening edge of the blank area is the same as the contour of one side of the device chip, and the area of the blank area is slightly smaller than or equal to the area of one side of the device chip.

[0023] According to the present invention, without arbitrarily increasing the distance between the device chip near the blank area and the solder resist layer constituting the module substrate, through the channel, it is possible to appropriately provide a method for effectively cleaning the flux residue, etc. in the blank area after the device chip is installed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a side structure diagram of a module (the first example) in an embodiment of the present invention.

[0025] Figure 2 It is an exploded structure schematic diagram of the main part of the first example.

[0026] Figure 3 is a sectional structure diagram of the main part of the first example, at Figure 5 the sectional view of the first example at the C-C position in

[0027] Figure 4 is a sectional structure diagram of the main part of the first example, at Figure 5 the sectional view of the first example at the D-D position in

[0028] Figure 5 is a sectional structure diagram of the main part of the first example, at Figure 3 the sectional view of the first example at the A-A position in

[0029] Figure 6 is a sectional structure diagram of the main part of the first example, at Figure 3 the sectional view of the first example at the B-B position in

[0030] Figure 7 is a structure diagram showing an example of a resonator formed on the functional surface of a device chip constituting an elastic wave device in the first example.

[0031] Figure 8 is a structure diagram showing an example of a circuit formed on the functional surface of a device chip constituting an elastic wave device in the first example.

[0032] Figure 9 is a sectional structure diagram of the main part of a module (the second example) in an embodiment of the present invention.

[0033] Figure 10 is a sectional structure diagram of a module of the prior art.

[0034] Figure 11 is a sectional structure diagram of the main part of the prior art.

[0035] The main reference numerals are as follows: 1 - module, 2 - module substrate, 2a - mounting surface, 2b - solder resist layer, 2ba - blank area, 2bb - opening edge, 2bc - surface, 2bd - thick surface, 2be - corner, 2c - bump pad, 3 - electronic device, 3a - elastic wave device, 4 - device chip, 4a - one surface, 4b - side surface, 4c - outer edge, 4d - center, 5, 50, 51 - resonator, 5a - IDT electrode, 5b - reflector, 5c - electrode finger, 5d - bus bar, 5e - electrode finger, 5f - bus bar, 6 - wiring, 7 - circuit, 8 - signal input / output terminal, 9 - ground terminal, 10 - bump, 10a - protruding end, 11 - gap, 11a - dimension, 12 - sealing portion, 13 - thin film, 14 - channel, 14a - first position, 14b - second position, 15 - sealing portion, x - propagation direction, L - interval. Specific Embodiment Based on the following Figures 1 to 9 , typical embodiments of the present invention will be described.

[0037] In this embodiment, more than two electronic devices 3 are mounted on a module substrate 2, and a part of the electronic devices 3 are device chips 4 that function as surface acoustic wave devices 3a (see Figure 1 ).

[0038] The surface acoustic wave device 3a is suitable for use as a frequency filter or the like in mobile communication devices and the like.

[0039] Typically, the module 1 is used as a power amplifier module integrated with a duplexer (Power Amplifier Module integrated Duplexer, abbreviated as PAMiD).

[0040] As other electronic devices 3 that are functionally different from the device chip 4 of the surface acoustic wave device 3a, typically include semiconductor devices having functions as power amplifiers, low-noise amplifiers, and switches, and passive components having functions as resistors, capacitors, coils, etc.

[0041] One surface 4a of the device chip 4 is designed as a functional element surface including IDT electrodes, typically as a functional surface formed with a resonator 5.

[0042] In addition, a wiring 6 for connecting between the resonators 5 and a circuit 7 composed of the wiring 6 for making the resonator 5 connectable to the outside are provided on one surface 4a of the device chip 4 (see Figure 8 ). In Figure 3 , Figure 4 and Figure 6 , the representation of the wiring 6 is omitted.

[0043] The resonator 5 and the wiring 6 are typically composed of a conductive metal film formed by photolithography and etching processes.

[0044] The device chip 4 has a function of propagating surface acoustic waves. Typically, the device chip 4 uses lithium tantalate or lithium niobate as a piezoelectric body. Additionally, in other embodiments, the device chip 4 can also be formed by laminating these piezoelectric bodies on a support such as sapphire, silicon, alumina, spinel, quartz, or glass.

[0045] Typically, the above device chip 4 is configured in a plate shape, and the plate shape can be a quadrilateral with a side length of 0.5 mm to 1 mm and a thickness of 0.15 mm to 0.2 mm.

[0046] Figure 7An example of a resonator 5 formed on one side 4a of a device chip 4 is shown. The resonator 5 includes an IDT electrode 5a and reflectors 5b located on both sides of the IDT electrode 5a. The IDT electrode 5a is composed of a plurality of electrode pairs, and each electrode pair is composed of a plurality of electrode fingers 5c. These electrode fingers are arranged in a cross-parallel manner in the length direction in the propagation direction x of the elastic wave, and one end of these electrode fingers is connected by a bus bar 5d. The reflector 5b is composed of a plurality of electrode fingers 5e. One end side of the plurality of electrode fingers 5e is connected by a bus bar 5f for each electrode pair. The plurality of electrode fingers 5e are arranged in parallel so that the length direction of the electrode fingers 5e intersects the propagation direction x of the elastic wave.

[0047] Figure 8 An example concept of a circuit 7 provided on a device chip 4 is shown. The symbol 50 represents a resonator 5 connected in series between signal input / output terminals 8, the symbol 51 represents a resonator 5 connected in parallel between signal input / output terminals 8, and the symbol 9 represents a ground terminal. The number and configuration of the resonators 5 are set as needed. That is, a ladder filter is constituted by the circuit 7 of Figure 8 .

[0048] As Figure 3 shown, bumps 10 protruding from one side 4a are provided on one side 4a of the device chip 4 thus constituted. The bumps 10 are made of solder and are typically formed at the corners or edges of one side 4a of the device chip 4 by means of solder paste transfer or the like, and their bases are fixedly connected to the wiring 6.

[0049] The module substrate 2 has a mounting surface 2a for the electronic device 3 and supports the electronic device 3 mounted on the mounting surface 2a.

[0050] In addition, the module substrate 2 has a solder resist layer 2b for covering the area to be covered on the mounting surface 2a.

[0051] Typically, the solder resist layer 2b is formed on the mounting surface 2a of the module substrate 2. Specifically, after wirings (not shown) on the module substrate 2 side and bump pads 2c are formed, the areas on the mounting surface 2a excluding the mounting area of the electronic device 3 and the areas not requiring coverage are used as the areas to be covered and formed on the mounting surface 2a.

[0052] On the module substrate 2, a blank area 2ba without the solder resist layer 2b is formed at a position below one side 4a of the device chip 4. In this blank area 2ba, the mounting surface 2a is exposed.

[0053] In the illustrated example, as Figure 2 shown, the device chip 4 appears as a rectangular plate when viewed from a direction perpendicular to one side 4a.

[0054] On the other hand, when viewed from a direction perpendicular to the mounting surface 2a of the module substrate 2, the opening edge 2bb of the blank area 2ba (i.e., the edge where the thick side 2bd of the solder mask layer 2b adjacent to the blank area 2ba meets the surface 2bc of the solder mask layer 2b around the blank area 2ba / see Figure 3 and Figure 4 ) is designed to imitate an imaginary rectangular contour.

[0055] In Figures 1 to 8 the first example shown, the contour of the opening edge 2bb of the blank area 2ba is the same as the contour of one surface 4a of the device chip 4, and the area of the blank area 2ba is slightly smaller than the area of one surface 4a of the device chip 4.

[0056] In contrast, in Figure 9 the second example shown, the contour of the opening edge 2bb of the blank area 2ba is the same as the contour of one surface 4a of the device chip 4, and the area of the blank area 2ba is equal to the area of one surface 4a of the device chip 4.

[0057] On the mounting surface 2a within the blank area 2ba, a bump pad 2c corresponding to the bump 10 is formed. In the illustrated example, the bumps are formed at the four corners of one surface 4a of the device chip 4, and correspondingly, the bump pads 2c are respectively formed at the four corners of the blank area 2ba (see Figure 2 ).

[0058] The device chip 4 typically mounts on the module substrate 2 by fixing the protruding end 10a of the bump 10 to the bump pad 2c located within the blank area 2ba through a process such as reflow soldering.

[0059] One surface 4a of the device chip 4 faces the mounting surface 2a of the module substrate 2 that is exposed within the blank area 2ba, and a gap 11 is formed between one surface 4a of the device chip 4 and the mounting surface 2a within the blank area 2ba due to the protruding amount of the bump 10 and the thickness of the bump pad 2c. Through the sealing portion 12 formed as described later, at an arbitrary position around the center 4d of the device chip 4, the gap 11 is sealed between the outer edge 4c of the device chip 4 and the surface 2bc of the solder mask layer 2b, and an internal space is formed below one surface 4a of the device chip 4, and the resonator 5 is located within this internal space.

[0060] The solder mask layer 2b is usually formed on the mounting surface 2a with a thickness range of 10 to 30 μm, but the size 11a of the gap 11 (see Figure 3)(It is) greater than the thickness of the solder mask layer 2b. Between one side 4a of the mounted device chip 4 and the surface 2bc of the solder mask layer 2b, around the periphery of the center 4d of the device chip 4, that is, at any position of the outer edge 4c, a gap L is formed in the direction perpendicular to one side 4a of the device chip 4.

[0061] In the first example, the outer edge 4c of one side 4a of the device chip 4 is in contact with the thick side 4b of the device chip 4, and the opening edge 2bb of the blank area 2ba is mounted within a range of 20 to 50 μm on the side of the center 4d of the device chip 4, relative to the center 4d of the device chip 4, around the periphery of the device chip 4, that is, at any position of the outer edge 4c.

[0062] In contrast, in the second example, the outer edge 4c of one side 4a of the device chip 4 is in contact with the thick side 4b, and the opening edge 2bb of the blank area 2ba and the outer edge 4c of the device chip 4 are mounted around the center 4d of the device chip 4, at any position of the outer edge 4c around the periphery of the device chip 4, and overlap each other when observed in the direction perpendicular to the one side.

[0063] Therefore, in the first and second examples, the gap L formed between one side 4a of the device chip 4 and the surface 2bc of the solder mask layer 2b is constant at any position around the center 4d of the device chip 4.

[0064] In the present embodiment, in order to ensure the formation of the internal space, before forming the sealing resin, a resin film 13 is used to cover the module substrate 2 and the device chip 4. The film 13 has insulation and flexibility.

[0065] The film 13 is usually covered on the device chip 4 in a vacuum environment after the device chip 4 is mounted, and then the air pressure above the film 13 is increased to make it closely adhere to the device chip 4 and the module substrate 2.

[0066] The gap L formed between one side 4a of the device chip 4 and the surface 2bc of the solder mask layer 2b is set to a size such that when the film 13 is closely adhered, no breakage occurs at the pulled-in part due to the film 13 being largely pulled into the blank area 2ba.

[0067] The size of the gap L is preferably set to a size less than 1.5 times the thickness of the film 13.

[0068] Specifically, the size of the gap L is considered according to factors such as the thickness and material of the film 13. The thickness of the film 13 is typically in the range of 20 to 50 μm. In this case, the size of the gap L is preferably set to 30 to 75 μm.

[0069] In addition, in the present embodiment, the solder resist layer 2b is formed with a channel 14 near the blank area 2ba. The channel 14 communicates with the blank area 2ba and has a first position 14a below one surface 4a of the device chip 4 and a second position 14b outside the thick side surface 4b of the device chip 4 and not below the one surface 4a of the device chip 4.

[0070] The number, length, width, shape of the channel 14, the distance between the first position 14a and the second position 14b, etc. can be changed as needed.

[0071] In the illustrated example, the channel 14 is a groove-like structure formed through the solder resist layer 2b in the solder resist layer 2b. That is, the bottom of the channel 14 is the mounting surface 2a of the module substrate 2. The length of the channel 14 is typically set such that the total length is 100 μm or more, and the length of the portion below the one surface 4a of the device chip 4 is 20 to 50 μm. In addition, in the illustrated example, the width of the channel 14 is substantially the same at any position.

[0072] When the channel 14 is a groove-like structure, it is preferably set such that the groove width is less than 1.5 times the thickness of the thin film 13. The thickness of the thin film 13 is typically in the range of 20 to 50 μm. In this case, the groove width of the channel 14 is preferably set to 30 to 75 μm.

[0073] The channel 14 is formed in the solder resist layer 2b by changing its position and is provided in a number of two or more. Among the two or more channels 14, at least one serves as an inlet for a fluid such as a cleaning liquid described later, and at least one other serves as an outlet for the fluid. In the illustrated example, the opening edge 2bb of the blank area 2ba is in a shape imitating the imaginary rectangular contour. In this case, typically at least one of the two or more channels 14 is provided on one side of the rectangle, and at least one other channel 14 is provided on the other side opposite to this side. Or, when at least one channel 14 is provided on one side of the rectangle, at least one other channel 14 is provided on the adjacent side of the rectangle.

[0074] In the illustrated example, the channels 14 are respectively formed at intermediate positions between the adjacent corners 2be of the blank area 2ba (see Figure 2 ). Each channel 14 extends along a direction perpendicular to the opening edge 2bb connecting the adjacent corners 2be of the blank area 2ba.

[0075] After the device chip 4 is installed, it is necessary to clean the flux residue, etc. in the blank area 2ba.

[0076] According to the structure described above, near the blank area 2ba, there is no need to arbitrarily increase the interval L between the solder mask 2b of the device chip 4 and the module substrate 2. Through the channel 14, it is possible to appropriately provide a module 1 with an effective means for cleaning flux residues and the like in the blank area 2ba after the installation of the device chip 4.

[0077] That is to say, the channel 14 increases the cross-sectional area of the flow path for sending fluids such as cleaning liquid into the blank area 2ba during cleaning, as well as the cross-sectional area of the flow path for discharging the fluid outside the blank area 2ba, without excessively increasing the interval L and without causing damage to the thin film 13.

[0078] After the device chip 4 and other electronic devices 3 are installed, a sealing portion 15 is formed on the mounting surface 2a of the module substrate 2. The sealing portion 15 is made of an insulating resin.

[0079] The sealing portion 15 is usually formed by coating the resin with a predetermined thickness on the mounting side of the electronic device 3 of an integrated substrate (not shown) serving as the module substrate 2, and then heating the resin to a predetermined temperature and curing it.

[0080] After that, the integrated substrate is cut according to the component areas of each module 1, thereby generating a plurality of modules 1 with the device chip 4 installed as a bare chip (see Figure 1 ).

[0081] Of course, the present invention is not limited to the embodiments described above, but includes all embodiments that can achieve the object of the present invention.

Claims

1. A module comprising an elastic wave device, characterized in that: The module includes two or more electronic devices mounted on a module substrate, wherein some of the electronic devices serve as device chips that function as elastic wave devices; One side of the device chip includes a functional element of an IDT electrode and a bump connected to the functional element, and a gap is formed between one side of the device chip and a mounting surface of the module substrate by utilizing the bump; The module substrate has a solder resist layer, and the solder resist layer is used to cover the area to be covered on the mounting surface; A blank area without a solder resist layer is formed in the solder resist layer below one side of the device chip; The solder resist layer forms two or more channels near the blank area, including the following two positions: a first position is located below one side of the device chip; and a second position is located outside a side surface of the device chip having thickness and is not located below one side of the device chip.

2. The module including the elastic wave device according to claim 1, characterized in that: The outer edge of one side of the device chip is connected to the side surface, and the opening edge of the blank area and the outer edge of the device chip overlap with each other at any position around the center of the device chip when the device chip is observed from a direction perpendicular to the one side, or the opening edge is located on the center side of the device chip within a range of 20 to 50 μm relative to the outer edge.

3. The module including the elastic wave device according to claim 1, characterized in that: The channel is a groove-shaped structure.

4. The module including the elastic wave device according to claim 1, characterized in that: The invention also includes a film covering the module substrate and the device chip, and a sealing resin formed on the film.

5. The module including the elastic wave device according to claim 4, characterized in that: The interval between one side of the device chip and the surface of the solder resist layer is set to a dimension smaller than 1.5 times the thickness of the film in a direction perpendicular to the one side of the device chip.

6. The module including the elastic wave device according to claim 5, characterized in that: The film thickness is 20 to 50 μm; the spacing size is 30 to 75 μm.

7. The module including the elastic wave device according to claim 1, characterized in that: The channel is a groove-shaped structure; it also includes a film covering the device chip and the module substrate, and a sealing resin formed on the film; the groove width of the channel is less than 1.5 times the thickness of the film.

8. The module including the elastic wave device according to claim 7, characterized in that: The channel has a groove width ranging from 30 to 75 μm; and the film thickness is ranging from 20 to 50 μm.

9. The module including the elastic wave device according to claim 1, characterized in that: The length of the channel is greater than 100 μm, and the length of a portion located below one surface of the device chip is 20 to 50 μm.

10. The module including the elastic wave device according to claim 1, characterized in that: The channel is connected to the blank area; the contour of the opening edge of the blank area is the same as the contour of one side of the device chip, and the area of ​​the blank area is slightly smaller than or equal to the area of ​​one side of the device chip.

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