JP2000138321A - Electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component of a structure, wherein an IC chip is jointed firmly to a container. SOLUTION: An electronic component 10 consists of an IC element 4, having conductive bumps 3 on the lower surface thereof and a container 1 having a cavity 2 for housing the IC element 4 and with the element 4 made to joint to the bottom of the cavity 2 of the container via the bumps 3, a thermosetting resin 5 is filled in the remaining space within the cavity 2 to have the resin 5 cured. With the resin 5 filled in such a way that the surface of the resin 5 becomes lower than the end edge of an aperture formed in the cavity 2 and becomes higher than the upper surface of the element 4, the distance between the element 4 and the wall surface of the cavity 2 is set smaller than the thickness of the element 4, and the distance between the upper surface of the element 4 and the surface of the resin 5 is set smaller than that between the element 4 and the bottom of the cavity 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component in which a flip-chip IC element is housed in a container having a cavity.

[0002]

2. Description of the Related Art An electronic component having a structure in which a flip chip IC element is mounted by a face bonding method via a bump in a cavity formed in a bottom surface of a container, and a resin is filled in a gap between the flip chip IC element and the bottom surface of the container. It has been known.

For example, a flip-chip IC element (hereinafter simply referred to as an “IC chip”) for performing temperature compensation of a crystal unit
As shown in FIG. 5, a gold Au bump 13 is provided in a cavity 12 of a container 11 formed by laminating ceramic layers in multiple layers.
Is accommodated such that the Au bump 13 is in contact with an electrode pad (not shown) on the bottom surface of the cavity 12. Then, the IC chip 14 is bonded to the cavity 12 of the container 11 through the Au bump 13 and the electrode pad by a method such as bonding with an Ag paste or fusion using an ultrasonic wave.
Bonded to the bottom of The mounting by the face bonding method in this way is due to the recent demand for smaller and thinner electronic components. However, the bonding strength of the bonding means such as bonding with an Ag paste or fusion with an ultrasonic wave alone is so low that the bonding is peeled off at a weight of 6 g per bump, so that the bonding between the IC chip 14 and the bottom surface of the cavity 12 is performed after bonding. The gap is filled with a thermosetting resin having a high shrinkage factor called an underfill resin, and the IC chip 14 is fixed to the bottom surface of the cavity 12 with the curing of the resin.

The quartz oscillator is mounted on the surface of the container 11 opposite to the surface on which the cavity 12 is formed and is hermetically sealed, but is not shown.

[0005]

However, while there is an increasing demand for a thinner container, application of an Ag paste is considered in consideration of the effects on components existing on the back side of a portion on which an IC chip is mounted, particularly on a quartz oscillator. It is necessary to reduce the amount and power of the ultrasonic wave for bonding.

[0006] A container mounted on another printed wiring board such as a motherboard such that the cavity side faces the board side, and another circuit element such as a capacitor is mounted in the same cavity as the cavity in which the IC chip is accommodated. However, there is a possibility that the capacitor electrode and the wiring pattern of the board are short-circuited.

Therefore, an object of the present invention is to provide an electronic component in which an IC chip is strongly bonded to a container.

[0008]

In order to achieve the object, an electronic component according to the present invention comprises an IC element having a conductive bump on a lower surface, the IC element being housed, and an electrode pad formed on a bottom surface. In the electronic component in which the remaining space in the cavity is filled and cured with a thermosetting resin while being bonded to a container having a cavity, the thermosetting resin has a surface lower than an opening edge of the cavity and an IC. Filled so as to be higher than the upper surface of the element, the distance between the IC element and the wall surface of the cavity is smaller than the thickness of the IC element, and the distance between the upper surface of the IC element and the surface of the thermosetting resin. Is smaller than the distance between the IC element and the bottom surface of the cavity.

In the above-mentioned conventional electronic component, as shown in FIG. 6, the thermosetting resin 15 shrinks in the direction of the arrow. With the contraction, a stress F is generated so that the IC chip 14 is pulled toward the bottom side of the cavity 12.
The C chip 14 was fixed.

On the other hand, the electronic component of the present invention has not only the contraction force of the resin filled in the gap between the IC chip and the bottom surface of the cavity, but also the contraction force of the resin filled around and on the top surface of the IC chip. Can be used. Therefore, the stress F for fixing the IC chip is larger than that of a conventional electronic component. However, when the filling amount of the thermosetting resin is higher than the opening edge of the cavity, this surface cannot be mounted on a motherboard or the like as a mounting surface, the cost increases, the curing takes a long time, and furthermore, the thickness is reduced. Therefore, it is important that the surface of the thermosetting resin is lower than the opening edge.

A suitable method for manufacturing the electronic component of the present invention is as follows.
From an electronic component precursor including an IC element having a conductive bump on a lower surface and a container in which a cavity for accommodating the IC element is formed, the IC element is joined to a bottom surface of the cavity of the container via a conductive bump. In a method of manufacturing an electronic component by filling and curing a thermosetting resin in a remaining space in a cavity, the thermosetting resin may have a surface lower than an opening edge of the cavity and an IC element. After filling so as to be higher than the upper surface, the ambient temperature is raised to the curing temperature at a stretch, the surface is cured first, and then the inside is cured.

As described above, when the ambient temperature is raised to the curing temperature at a stretch after the resin is filled and the surface is cured first, the shrinkage of the resin generates a force to pull the previously cured surface to the bottom of the cavity. Is also pressed down on the bottom side and is strongly fixed.

[0013]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an electronic component according to the embodiment.

The electronic component 10 includes a container 1 formed by laminating three ceramic insulating layers 1a, 1b, and 1c each having a wiring pattern, and an IC chip 4. The space surrounded by the inner circumferences of the frame-shaped insulating layers 1a and 1b and the plate-shaped insulating layer 1c becomes the cavity 2 for accommodating the IC chip 4. IC
Au bumps 3 are formed in advance on the electrode portions of the chip 4, and the bumps 3 of the IC chip 4 are bonded to the electrode pads 6 on the insulating layer 1c by adhesion with Ag paste or fusion by ultrasonic waves. Thereby, it is electrically connected to the electrode pad 6 formed on the bottom surface of the container 1. The IC chip 4 is mechanically fixed by this bonding, but is strongly fixed by filling the remaining space of the cavity 2 with a thermosetting resin 5 and curing the resin.

As the resin 5, for example, an epoxy resin having a viscosity of 3000 cps, a linear expansion coefficient of 30 ppm, and a shrinkage of 1.7% is commercially available. The resin 5 is filled without a gap so that the surface thereof is located between the upper surface of the IC chip 4 and the opening edge of the cavity 2. Then, after filling, the temperature is raised to the curing temperature of the resin at a stretch. This causes the surface to harden and shrink first, and the shrinking force causes IC
The chip 4 is pressed toward the insulating layer 1c.

Further, as shown in FIG. 2, when the distance between the IC chip 4 and the wall surface of the cavity 2 is B and the thickness of the IC chip 4 is T, as shown in FIG. Is preferable. This is because, considering the relationship between the stress F for holding down the IC chip 4 and the distance B, the stress F decreases as B increases and becomes constant when B exceeds T as shown in FIG. The reason for this is that when the shape of the area S of the T × B rectangle surrounded by the dashed line in FIG. 2 is T> B, the length becomes longer and the contraction force in the vertical direction becomes larger.
Conversely, when T <B, the area S becomes horizontally long, and only the lateral contraction force increases, but the stress F for holding down the IC chip 4 decreases. However, B must be at least 0.05 mm. If B is smaller than this, IC
When the chip 4 is accommodated, the IC chip 4
The IC chip 4 cannot be stably accommodated by contacting the wall surface of
Also, the IC chip 4 may be missing.

When the distance between the upper surface of the IC chip 4 and the surface of the resin 5 is C and the distance between the IC chip 4 and the bottom surface of the cavity 2 is A, the stress F increases as shown in FIG. , And becomes maximum when C is equal to A. This is because when C becomes larger than A, the shrinking force of the resin above the IC chip 4 becomes larger than the shrinking force of the resin below the IC chip 4.

In some cases, a circuit element such as a capacitor is housed in the cavity 2 in addition to the IC chip 4. For example, when the electronic component is a crystal oscillator and the IC chip 4 is used for temperature compensation of a crystal unit, the IC chip 4
It is necessary to cut high-frequency noise superimposed on a power supply voltage supplied to an oscillation inverter integrated (IC). Further, it is necessary to prevent the AC component from being superimposed on the output signal of the oscillation inverter. In order to achieve these objects without complicating the external circuit, the cavity 2 is used.
A capacitor is also mounted inside. In this case, if the capacitor is thinner than the IC chip 4, the resin 5 covers the IC chip 4 and also covers the capacitor. Conversely, even if the capacitor is thicker, it is preferable to fill the resin 5 just enough to cover the capacitor as long as it does not exceed the opening edge of the cavity 2. In the case of a crystal oscillator, since the crystal resonator is mounted on the opposite side of the cavity with the container as a partition, the cavity is mounted on the motherboard with the cavity facing the motherboard side. This is because a short circuit with the wiring is prevented.

[0019]

As described above, according to the present invention, the substantial bonding strength of the IC chip to the container can be increased, so that the electronic component can be further thinned.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an electronic component according to an embodiment.

FIG. 2 is a stress diagram acting on the electronic component of the embodiment.

FIG. 3 shows a distance B between the IC chip and the wall surface of the cavity;
4 is a graph showing a relationship with a stress F acting on an IC chip.

FIG. 4 shows a distance A between the IC chip and the bottom surface of the cavity;
4 is a graph showing a relationship with a stress F acting on an IC chip.

FIG. 5 is a sectional view showing a conventional electronic component.

FIG. 6 is a stress diagram acting on a conventional electronic component.

[Explanation of symbols]

 1,11 container 2,12 cavity 3,13 bump 4,14 IC chip 5,15 resin 10 electronic component

Claims (1)

[Claims] An IC element having a conductive bump on a lower surface is joined to a container containing the IC element and having a cavity having an electrode pad formed on a bottom surface, and a thermosetting resin is formed in a remaining space in the cavity. In the electronic component filled and cured, the thermosetting resin is filled so that its surface is lower than the opening edge of the cavity and higher than the upper surface of the IC element. Is smaller than the thickness of the IC element, and
The distance between the upper surface of the element and the surface of the thermosetting resin is IC
An electronic component having a distance smaller than a distance between an element and a bottom surface of a cavity.