JP2003218251A - Electronic device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device and a method of manufacturing the same which enables to stop the flow of resin to fill a space between a circuit element and a package at a certain position to form a hollow section accurately. <P>SOLUTION: The electronic device comprises the circuit element 10 having a function section 12 and electrodes 13 on the bottom, and a package 1 having a cavity 2 wherein the circuit element 10 is stored and has electrode pads 3 formed on the bottom. The electrodes 13 of the circuit element 10 and the electrode pads 3 of the package 1 are connected by bumps 15, and a space between the circuit element 10 and the cavity 2 is sealed by the resin 20. In an inside wall of the cavity 2 which faces a side face of the circuit element 10, a step section 4 is formed on the entire circumference so that a space δbetween the cavity and the side face of the circuit element 10 is larger on the bottom side than on the opening side. Then, the resin 20 is supplied into part of the cavity 2 from the opening to the step section 4, and is hardened. As a result, the hollow section 21 is formed between the bottom of the circuit element 10 and the bottom of the cavity 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device in which a circuit element is flip-chip mounted in a package having a cavity and a resin is provided between the circuit element and the package, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the case of an electronic device in which a circuit element such as a semiconductor element is flip-chip mounted in a cavity type package, it is known that a lid is adhered to the package in order to remove the sealing. Kaihei 10-65
No. 071). However, in order to cover the lid, a step of applying an adhesive and a step of adhering the lid and the package to each other are required, and the number of steps increases, and the size and size of the lid are reduced. There was a limit.

[0003]

Therefore, as a structure for reducing the number of steps, downsizing, and height reduction, Japanese Unexamined Patent Publication No. 2000-13 has been proposed.
Japanese Patent No. 8321 proposes an electronic device which is sealed with a resin instead of a lid. FIG. 8 shows an example of the electronic device. In the figure, 30 is a package, 31 is a cavity, 32 is an electrode pad formed on the bottom surface of the cavity 31, 33 is a circuit element, and 34 and 35 are circuit elements 33.
Electrodes and functional portions formed on the lower surface of the
Is a bump for joining the electrode pad 32 with the electrode pad 32, and 37 is a sealing resin.

In the case of the above electronic device, the cavity 31
Since the gap between the inner wall of the cavity 31 and the side surface of the circuit element 33 is substantially constant in the depth direction, the resin 37 poured into the opening of the cavity 31 is capillarized to cause the inner wall of the cavity 31 and the side surface of the circuit element 33. Will pass through the gap between and to the lower surface side of the circuit element 33 provided with the functional portion 35. When the resin 37 wraps around to the lower surface side of the circuit element 33 in this way, there is a problem that the electrical characteristics of the circuit element 33 are affected by the dielectric constant and the dielectric loss that are material characteristics of the resin 37. In addition, the circuit element 33 is SA
In the case of a piezoelectric vibrator such as a W element, the vibrating part 35 is made of resin 3
Since it is dumped by 7, there arises a problem that the characteristic itself is not expressed. There is also a method of using a high-viscosity resin so that the resin 37 does not go around to the lower surface side of the circuit element 33, but if the gap between the circuit element 33 and the cavity 31 varies on four sides, the resin penetration depth can be made uniform. However, there is a possibility that the sealing property and the fixing strength may vary.

Therefore, it is an object of the present invention to provide an electronic device and a method for manufacturing the same which can accurately form a hollow portion by stopping the flow of the resin filled in the gap between the circuit element and the package at a fixed position. .

[0006]

In order to achieve the above object, the invention according to claim 1 is such that a circuit element having a functional portion and an electrode on the lower surface, the circuit element is accommodated, and an electrode pad is formed on the bottom surface. A package having a cavity formed therein, the electrodes of the circuit element and the electrode pads of the package are connected by bumps, and the circuit element and the cavity are sealed with a resin. The inner wall of the cavity facing the side surface of the cavity is provided with a step portion whose gap with the side surface of the circuit element is larger on the bottom side than on the opening side, and the resin is stepped from the opening of the cavity. The electronic device is characterized in that a hollow portion is formed between the lower surface of the circuit element and the bottom surface of the cavity, which is filled and hardened in one area up to the portion.

The invention according to claim 4 has a step of preparing a circuit element having a functional portion and an electrode on the lower surface, and a cavity having an electrode pad formed on the bottom surface for accommodating the circuit element. , A package is provided in which an inner side wall of the cavity facing the side surface of the circuit element is provided with a step portion whose gap with the side surface of the circuit element is larger on the bottom side than on the opening side substantially all around. A step, a step of forming a bump on at least one of the electrode of the circuit element and an electrode pad of the package, a step of connecting the electrode of the circuit element and an electrode pad of the package by a bump, the circuit element and the cavity And a step of sealing the resin between the lower surface of the circuit element and the bottom surface of the cavity while leaving a hollow portion between the lower surface of the circuit element and the bottom surface of the cavity. Filling range up parts, to provide a curing method for manufacturing the electronic device, characterized in that it comprises a.

According to the present invention, the inner wall of the cavity facing the side surface of the circuit element is provided with a step portion whose gap between the side surface of the circuit element and the side surface of the circuit element is larger on the bottom side than on the opening side. is there. The resin that has flowed into the opening of the cavity flows into the gap between the inner wall of the cavity and the side surface of the circuit element due to the capillary phenomenon, but the gap between the inner wall of the cavity and the side surface of the circuit element suddenly expands due to the stepped portion. Therefore, the contact angle between the resin and the step portion is reduced, and the resin flow is stopped. Therefore, the resin is prevented from flowing into the lower surface side of the circuit element, and the hollow portion can be stably formed between the lower surface of the circuit element and the bottom surface of the cavity. Since the resin does not adhere to the functional portion of the circuit element, it is possible to prevent the electrical characteristics of the circuit element from being affected by the dielectric constant and the dielectric loss of the resin. Further, even if the gap between the side surface of the circuit element and the inner wall of the cavity varies on the four sides, the resin flow can be reliably stopped at the step portion, so the resin penetration depth is defined by the step portion. Therefore, the sealing property and the fixing strength are constant on the four sides around the circuit element, and an electronic device with stable performance can be obtained. Further, since it can be sealed with resin, it is not necessary to attach a lid to the package, the number of steps can be reduced, and the electronic device can be downsized and the height can be reduced.

The step portion in the present invention functions as a resin stopper portion, and is provided almost all around the inner wall of the cavity facing the side surface of the circuit element, and the gap with the side surface of the circuit element is the opening. It is sufficient to include at least a portion in which the bottom side is larger than the side side. Therefore, a convex portion, a concave portion, a curved surface, or the like may be provided adjacent to the upper portion or the lower portion of the step. The step portion does not have to be provided on the entire circumference of the inner wall of the cavity, and may have a portion where the step portion is partially cut off as long as it functions as a resin stopper. The resin is preferably an epoxy resin composition, but is not limited to this. The lower the viscosity of the liquid resin, the more preferable the filling operation is completed in a short time. If the viscosity is too high, it will not enter the narrow space, so it is preferable that the viscosity of the liquid sealing resin be 500 Pa · s or less. The resin can be cured by a method suitable for the resin material such as heating, UV irradiation, electron beam irradiation, or the like.

As described in claim 2, the height from the lower surface of the circuit element to the step portion is preferably 0.1 mm or less. The step provided on the inner wall of the cavity prevents the resin from flowing out to the element side, but the resin flows out to the package side when the height t from the lower surface of the circuit element to the step is large. . Therefore, by setting the height from the lower surface of the circuit element to the step portion to 0.1 mm or less, it is possible to reliably prevent the resin from flowing out to the package side.

According to a third aspect of the present invention, the upper surface of the circuit element is positioned lower than the surface of the opening of the cavity, and resin is filled between the upper surface of the circuit element and the side surface of the circuit element and the inner wall of the cavity. Good. In this case, since the recess is formed by the upper surface of the circuit element and the opening of the cavity, when the resin is poured into this recess, the resin spreads to the opening of the cavity and the side surface of the circuit element and the inner wall of the cavity are formed. The resin can be evenly flowed around the entire circumference of the circuit element by one filling. Further, since the resin covers not only the side surface of the circuit element but also the upper surface, the insulating property between the circuit element and the outside is improved, and the holding strength is also increased.

[0012]

1 shows an example of an electronic device according to the present invention. In this electronic device, a circuit element 10 is mounted face down on a package 1. The package 1 is made of a ceramic material such as alumina and a material having airtightness, electrical insulation and heat resistance such as glass epoxy resin. The package 1 is formed with a cavity 2 having an upper opening, and a plurality of electrode pads 3 are formed on the bottom surface of the cavity 2. Each of these electrode pads 3 is led out of the package 1.

A circuit element 10 is provided on the inner wall of the cavity 2.
A step portion 4 is provided on the entire circumference so that the gap with the side surface of the bottom side is larger than that on the opening side. That is, the inner wall of the cavity 2 has an overhang shape. This step portion 4 has the circuit element 10 mounted thereon.
Is formed at a height facing the side surface of the. That is, the height h ₁ from the bottom surface of the cavity 2 to the step portion 4 is lower than the height h ₂ from the bottom surface of the cavity 2 to the top surface of the circuit element 10 in the mounted state, and the height h ₁ to the bottom surface of the circuit element 10. Higher than ₃ . The depth h ₄ of the cavity 2 is the height h from the bottom surface of the cavity 2 to the top surface of the circuit element 10.
Greater than ₂ .

As a method of forming the package 1 having the step portion 4, various methods can be considered as shown in FIG. FIG. 2A shows a structure in which three ceramic layers 1a, 1b, 1c are laminated, a hole 1a _{1 which} is an opening of the cavity 2 is formed in the first layer 1a, and a second layer 1b is formed. A hole 1b ₁ larger than the hole in the first layer 1a is formed. No holes are provided in the third layer 1c. Further, FIG. 2B shows a pair of package members 1d and 1d having a step portion 4 formed on the inner surface thereof.
e is bonded to face each other. In FIG. 2C,
By fixing the frame-shaped member 1f to the inner surface of the opening of the cavity 2 of the package 1 having no step portion, the step portion 4 is formed.
Is formed. The method of forming the step portion is not limited to the above.

The circuit element 10 of this embodiment is a surface acoustic wave chip, and as shown in FIG. 3, crystal, LiTaO ₃ ,
Two sets of IDT electrodes 12 made of Al or the like and four input / output electrodes 13 made of Ti / Ni / Au or the like are formed on the main surface of a piezoelectric substrate 11 made of LiNbO ₃ or the like.
The IDT electrode 12 and the input / output electrode 13, which are the functional parts, are connected to each other. A bump 15 is fixed to each of the input / output electrodes 13. As the bump 15, Au,
A metal bump containing Ag, Pd, or Cu as a main component, a solder bump, or the like can be used. The bumps 15 are formed by using a plating method, a wire bonding method, or the like. Here, the Au bumps are formed by the wire bonding method. The outer size of the circuit element 10 is smaller than the inner size of the opening of the cavity 2, and the gap δ (see FIG. 1) on each side is a gap in which a liquid sealing resin 20 described later is filled by a capillary phenomenon. The viscosity of the liquid sealing resin is 500P
In the case of a · s or less, the gap δ is preferably 0.3 mm or less.

A sealing resin 20 made of, for example, an epoxy resin is injected into the opening of the cavity 2,
It is hardened. A part of the liquid resin 20 flows into the gap between the side surface of the circuit element 10 and the inner side wall of the cavity 2 due to a capillary phenomenon, but the step portion 4 causes a sharp gap between the inner side wall of the cavity 2 and the side surface of the circuit element 10. Since it expands, the contact angle between the resin 20 and the step portion 4 decreases, and the flow of the resin 20 is stopped. Therefore, the resin 20 is prevented from flowing into the lower surface side of the circuit element 10, and the hollow portion 21 can be formed between the lower surface of the circuit element 10 (the surface provided with the functional portion 12) and the bottom surface of the cavity 4. . Since the resin 20 does not adhere to the functional portion 12 of the circuit element 10, the vibration characteristics of the circuit element 10 are not adversely affected. Further, the electric characteristics of the circuit element 10 are not affected by the dielectric constant and the dielectric loss of the resin 20. After the resin 20 is injected in a predetermined amount, the resin 20 is cured. A known method such as heating, UV irradiation, or electron beam irradiation may be used.

Here, a method of manufacturing the electronic device having the above structure will be described with reference to FIG. Figure 4
As shown in (a), the package 1 having the cavity 2 and the electrode pad 3 formed on the bottom surface thereof is prepared. On the inner wall of the cavity 2, a step portion 4 whose bottom side is expanded from the opening side is provided all around. Also, the IDT on the bottom
The electrode 12 and the input / output electrode 13 are formed, and the input / output electrode 1
A circuit element 10 having bumps 15 formed on the surface 3 is prepared. Then, the upper surface of the circuit element 10 (the surface on which the IDT electrode 12 is not provided) is adsorbed by the thermocompression bonding tool A, and the electrode pads 3 of the package 1 and the bumps 15 of the circuit element 10 are positioned so as to correspond to each other vertically. The bumps 15 are bonded to the electrode pads 3 by applying heat and pressure with the thermocompression bonding tool A. Not limited to thermocompression bonding, ultrasonic bonding may be performed, and ultrasonic waves and thermocompression bonding may be used together. By thermocompression bonding, a part of the bump 15 is crushed and the bump 15 and the electrode pad 3 are diffusion-bonded. In the joined state, a predetermined gap δ is formed between the cavity 2 and the circuit element 10. Next, as shown in FIG. 4B, when the liquid sealing resin 20 is supplied to the inside of the cavity 2, that is, the upper surface of the circuit element 10 by the dispenser B, the resin 20 is caused by the capillary phenomenon to the side surface of the circuit element 10. Flows into the gap δ between the inner wall of the cavity 2 and the inner wall of the cavity 2. Since the contact angle of the resin 20 that has flowed to the step portion 4 decreases at the step portion 4, the flow of the resin 20 stops. Therefore, the circuit element 10
The hollow portion 21 is formed between the lower surface of the circuit element 10 and the bottom surface of the cavity 2, so that the resin 20 does not adhere to the functional portion 12 of the circuit element 10. Further, since the penetration depth of the resin 20 is defined by the step portion 4, it is always a constant depth, and the sealing property and the fixing strength are stable. After applying the sealing resin 20, the package 1 is put into a curing furnace to cure the sealing resin 20, and the resin-sealed electronic device shown in FIG. 1 is completed.

FIG. 5 shows the relationship between the height t (= h ₁ -h ₃ ) from the lower surface of the circuit element 10 to the step portion 4 and the gap δ and the resin outflow. The ○ mark indicates that the resin 20 does not flow out, and the Δ mark indicates that the resin 20 indicates the step portion 4 as shown in FIG.
It shows the case of flowing downward. In any case, resin 20
Does not flow out to the lower surface side of the circuit element 10. As is clear from FIG. 5, when the height t of the step portion 4 is 0.10 mm or less, the resin 20 can be prevented from flowing out to the lower side of the step portion 4.

FIG. 7 shows various combinations of the shape of the step portion 4 of the package 1 and the side surface shape of the circuit element 10. The shape of the step portion 4 is the same as that of FIG. 1 (1),
4), 7), 10)), those in which the circumferential groove 4a is formed on the inner wall of the cavity 2 (2), 5), 8), 11)), and the circumferential projection 4b is formed on the inner wall of the cavity 2. Things (3), 6), 9), 12))
3 types are shown. The side shape of the circuit element 10 is
1 (1), 2), 3)) with the same shape as in FIG. 1, a concave step 10a formed on the lower end of the side surface (4), 5), 6)), and a protrusion 10b formed on the central part of the side surface. (7), 8), 9)) and the one in which the groove 10c is formed in the central portion of the side surface (10), 11), 12)) are shown. In any case, the resin 20 is
The flow can be stopped and the hollow portion can be formed reliably.

The present invention is not limited to the above embodiment. In the above embodiment, the bump 15 is formed on the electrode 13 of the circuit element 10, but the bump 15 may be formed on the electrode pad 3 of the package 1. Alternatively, bumps may be formed on both the electrode 13 and the electrode pad 3, and the bumps may be abutted and joined to each other. In the above embodiment, the example in which the upper surface of the circuit element 10 is lower than the upper surface of the package 1 and the resin 20 is applied to the side surface and the upper surface of the circuit element 10 has been described, but the upper surface of the circuit element 10 is referred to as the upper surface of the package 1. It may be approximately the same height or higher. In this case, the resin 20 does not have to be applied to the upper surface of the circuit element 10, but may be applied to the annular gap between the inner wall of the cavity 2 and the side surface of the circuit element 10. The circuit element of the present invention is not limited to the surface acoustic wave element, and it goes without saying that it may be another circuit element such as a high frequency element or a semiconductor element as long as it is an element having a functional portion and an electrode on the lower surface. . However, the sealing structure of the present invention is effective in the case of an element such as a surface acoustic wave element whose functional portion is composed of an electrode such as aluminum which is easily corroded.

[0021]

As is apparent from the above description, claim 1
According to the invention described in (3), a step portion whose gap between the side surface of the circuit element and the side surface of the circuit element is larger on the bottom side than on the opening side is provided substantially all around the inner side wall of the cavity facing the side surface of the circuit element. Therefore, the resin poured into the opening of the cavity is
Due to the capillary phenomenon, it flows into the gap between the inner wall of the cavity and the side surface of the circuit element, but due to the stepped portion, the gap between the inner wall of the cavity and the side surface of the circuit element expands rapidly, and the flow of resin is stopped. Therefore, the resin is prevented from flowing into the lower surface side of the circuit element, and the hollow portion can be stably formed between the lower surface of the circuit element and the bottom surface of the cavity.
Since the resin does not adhere to the functional portion of the circuit element, it is possible to prevent the electrical characteristics of the circuit element from being affected by the dielectric constant and the dielectric loss of the resin. Further, even when the circuit element is a vibrator, the characteristics are not adversely affected. Further, even if the gap between the side surface of the circuit element and the inner side wall of the cavity varies on the four sides, the resin flow is reliably stopped at the step portion, so that the resin penetration depth is kept constant by the step portion. Therefore, the sealing property and the fixing strength are constant on the four sides around the circuit element, and an electronic device with stable performance can be obtained. Further, since it can be sealed with resin, it is not necessary to attach a lid to the package, the number of steps can be reduced, and the electronic device can be downsized and the height can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an electronic device according to the present invention.

2 is a cross-sectional view of some manufacturing examples of a package used in the electronic device shown in FIG.

FIG. 3 is a perspective view of an example of a circuit element used in the electronic device shown in FIG.

FIG. 4 is a manufacturing process diagram of the electronic device shown in FIG. 1.

FIG. 5 is a distribution diagram showing the outflow of resin depending on the step position.

FIG. 6 is an enlarged view showing a state where resin flows out to a step portion.

FIG. 7 is a diagram showing various combinations of a stepped shape of a package and a side surface shape of a circuit element.

FIG. 8 is a cross-sectional view of a conventional electronic device.

[Explanation of symbols]

1 package 2 cavities 3 electrode pad 4 step 10 circuit elements 12 IDT electrode (functional part) 13 Input / output electrodes 15 bumps 20 sealing resin 21 hollow

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nishikawa Etsuo             Stock number 2 26-10 Tenjin, Nagaokakyo-shi, Kyoto             Murata Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. An electrode of the circuit element and an electrode of the package, comprising: a circuit element having a functional part and an electrode on a lower surface; and a package having the cavity for accommodating the circuit element and having an electrode pad formed on a bottom surface thereof. In an electronic device in which a pad is connected with a bump and a space between the circuit element and the cavity is sealed with a resin, a gap between the side surface of the circuit element and an opening is formed in an inner wall of the cavity facing the side surface of the circuit element. The step portion whose bottom side is larger than the bottom side is provided substantially all around, and the resin is filled and hardened in a range from the opening of the cavity to the step portion, and the lower surface of the circuit element and the bottom surface of the cavity. An electronic device characterized in that a hollow portion is formed between and. 2. The electronic device according to claim 1, wherein the height from the lower surface of the circuit element to the step portion is 0.1 mm or less. 3. The upper surface of the circuit element is lower than the surface of the opening of the cavity, and the resin is filled between the upper surface of the circuit element and the side surface of the circuit element and the inner wall of the cavity. The electronic device according to claim 1 or 2, which is characterized. 4. A step of preparing a circuit element having a functional portion and an electrode on a lower surface, and a cavity having an electrode pad formed on a bottom surface for accommodating the circuit element, and facing a side surface of the circuit element. A step of preparing a package on the inner side wall of the cavity, in which the gap between the side surface of the circuit element is larger on the bottom side than on the opening side is provided on substantially the entire circumference; Forming bumps on at least one of the top and the electrode pads of the package,
A step of connecting the electrode of the circuit element and an electrode pad of the package with a bump, and a step of sealing the space between the circuit element and the cavity with a resin, wherein the lower surface of the circuit element and the bottom surface of the cavity are With the hollow part left in
Filling the range from the opening of the cavity to the stepped portion with the resin, and curing the resin.