KR20050025413A - Package structre and packaging method for vibration sensor - Google Patents

Abstract

A package structure of a vibration sensor and a method for packaging the vibration sensor are provided to improve the productivity by changing a silicon rubber damping structure into a spring damping structure. A package structure of a vibration sensor includes a substrate(12). A sensor chip(22) is positioned above a hole formed at the substrate(12) in such a manner that the sensor chip(22) is separated from the substrate(12). The sensor chip(22) is bonded with a wire(24). A silicon rubber(26) is filled in the hole formed in the substrate(12). The sensor chip(22) does not directly make contact with the substrate(12), but is elastically fixed by means of the silicon rubber(26). The silicon rubber(26) acts as a damper capable of absorbing vibration.

Description

Package structure and packaging method for vibration sensor

The present invention relates to a package structure and a packaging method of a vibration sensor, a gyro sensor element.

The vibration sensor refers to a device for detecting vibration. That is, the device detects a physical vibration and outputs an electrical signal corresponding to the vibration. Gyro sensor, also called angular velocity sensor, is a sensor used in camcorder for image stabilization, small aircraft attitude control, and car navigation system. At present, these vibration sensors and gyro sensors are manufactured in miniatures thanks to semiconductor technology.

Vibration sensors and gyro sensors absorb the vibration caused by the contact of the instrument on which the sensor is mounted or vibration by sound waves as much as possible, while displacement of the operation state (angular velocity, gravity acceleration, rotation angle, etc.) when the instrument is moving or shaking. ) Should be detected. To this end, conventionally, a metal spring is used as a damper to dampen unnecessary vibration transmitted from the outside of the sensor as shown in FIGS. 1A and 1B.

In FIG. 1A, a plurality of damper springs 14 are installed on the bottom of a substrate (generally a PCB) 12 of a sensor package 10 on which a sensor and a sensor driving component are mounted. That is, the sensor package 10 is installed in a floating form by the damper springs 14. More detailed installation structure is shown in Figs. 1b and 1c. FIG. 1B is a plan view of the damp spring 14, in which a central portion 14a is formed helically from the peripheral portion 14b, and the central portion 14a has elasticity. 1C is a side view of the damper spring 14, and it can be seen that the substrate 12 of the sensor package and the central portion 14a of the damper spring are elastically bonded. The damping spring 14 damps the sensor package 10 in a state spaced apart from the apparatus at a predetermined interval to absorb vibrations or contacts that are meaningless for measurement.

However, in the conventional structure as described above, since the central portion 14a of the spring must be electrically connected to the bonding pad of the substrate by soldering or spot welding, the manufacturing cost increases, the defective rate increases, and the package size increases.

The present invention aims to minimize the package size by replacing the conventional spring damper method with a silicon rubber type to improve the manufacturability and reduce the production cost and ultimately mount the sensor on the substrate.

The present invention improves the above-mentioned disadvantages of the prior art and, in particular, wire-bonds the sensor chip directly on the substrate in a method for thinning and reducing the package size, while the sensor chip (Die) is mounted while being spaced apart from the substrate. The present invention relates to a semiconductor package structure and packaging method for filling a silicon rubber in the spaced space so as to reduce the vibration of the sensor chip with the silicon rubber.

There are two cases as an embodiment embodying the concept of the above invention. 2A shows a first embodiment, in which the sensor chip 22 is raised and bonded with wires 24 so as to be spaced apart from the base 12 at an upper portion where the hole 20 is formed in the base 12. Then, the silicon rubber 26 is filled thereon. Therefore, the sensor chip is elastically fixed in a floating state through the silicon rubber without directly contacting the substrate, and the silicon rubber can act as a damper to absorb vibrations that are meaningless for measurement. In the first embodiment, since the sensor chip is located only on one side of the substrate, space utilization of the substrate is facilitated, but the thickness of the package is increased because the sensor chip is separated from the substrate by a predetermined distance.

FIG. 2B shows a structure in which the sensor chip 22 enters the inner space of the hole 20 'formed in the base 12 as the second embodiment. That is, a hole is formed in the substrate to be larger than a sensor chip, and wire bonding is performed while the sensor chip is positioned so that the substrate does not come into contact with the substrate, and then the silicon rubber 26 is filled between the substrate and the sensor chip. That is, the sensor chip is mounted through the silicon rubber so as not to contact the substrate in the hole of the substrate. In the second embodiment, since the sensor chip is not floating from the substrate but positioned in the same plane as the substrate, the thickness of the final package is reduced, while the sensor chip occupies both sides of the substrate, so that the space of the substrate is reduced. There is a disadvantage in reducing the utilization.

Since the above embodiments merely illustrate preferred embodiments for implementing the concept of the present invention, it is obvious that the technical scope of the present invention is not limited to the above embodiments.

Meanwhile, a packaging method for manufacturing a package structure according to the present invention will be described.

The packaging method of the present invention consists of the steps 1 to 4 of FIG. 3A and the 5 to 8 steps of FIG. 3B. 3A and 3B, the upper side of each process step means a side view, and the lower side means a plan view. 3A and 3B illustrate the case of the second embodiment of the package structure of the present invention as an example, but the same applies to the case of the first embodiment. Such modifications will be apparent to those skilled in the art.

Step 1: A hole 20 larger than the size of the sensor chip is formed in the base 12. The sensor chip enters the hole so that a space remains. The shape and size of the hole may be determined according to the shape, size, vibration absorption degree, and the like of the sensor chip.

Step 2: The jig 32 having the protrusion 30 in which the concave groove 28 is formed to accommodate the sensor chip is inserted from the bottom of the base 12 to the top. Since the distance between the sensor chip and the hole of the substrate should be increased, the periphery of the protrusion on the upper part of the jig is preferably sized to be in close contact with the inside of the hole of the substrate, and the recessed groove formed in the protrusion may be accommodated in close contact with the sensor chip. It is desirable that the size.

Step 3: The sensor chip 22 is placed in the concave groove of the protrusion of the jig inserted into the hole of the base 12. In this state, the sensor chip and the substrate are spaced apart at a predetermined interval. The separation distance d may be determined by the vibration absorption characteristics of the sensor chip, wire, silicon rubber, and the like.

Step 4: Bonding is performed between the bonding pads (not shown) of the sensor chip and the pads (not shown) of the substrate with a wire 24. This wire bonding is a known technique in the manufacture of semiconductor devices.

Step 5: The liquid silicon rubber 26 is applied to the wire bonded sensor chip 22. The viscosity of the silicon rubber will be determined by the intensity absorption characteristics of the sensor chip. It is also possible to use a mixture of conductive fine powder for the purpose of electronic shielding (conductive fine powder for shielding). The silicon rubber acts as a damper between the sensor chip and the substrate.

Step 6: Curing in Electric Furnace

7 process: 7 process is the same as a normal package process. Step 7 is a passivation step, in which an epoxy resin 34 or the like is used to cover the sensor chip and the base material.

Step 8: Remove Jig. When the jig is removed, the sensor chip is supported only by the silicon rubber, not in contact with the substrate, so that the damping action of the silicon rubber absorbs the vibration to the sensor chip.

According to the present invention, the change from the existing spring damper method to the silicon rubber damping method can improve the manufacturability and reduce the production cost, and ultimately, since the sensor is mounted on the substrate, the thickness can be reduced and the package size can be minimized. .

1a to c is a view showing a vibration absorption method of the conventional vibration sensor.

2A is a structural diagram showing a first embodiment of the present invention.

Fig. 2B is a structural diagram showing a second embodiment of the present invention.

Figure 3a, b is a process flow diagram of a vibration sensor packaging method according to the present invention.

Claims (2)

The sensor chip is directly wire-bonded on the substrate, but the sensor chip (Die) is mounted in a state spaced apart from the substrate, and the vibration sensor package that attenuates the vibration on the sensor chip with the silicon rubber by filling the silicon rubber in the space separated from the substrate. rescue. Forming a hole larger than the size of the sensor chip in the substrate, Inserting a jig having a protrusion in which a concave groove is formed to accommodate the sensor chip into a substrate; Placing the sensor chip in the concave groove of the projection of the jig inserted into the hole of the substrate, and wirebonding between the bonding pad of the sensor chip and the pad of the substrate, Applying a liquid silicon rubber to the wire-bonded sensor chip, and curing (curing), packaging method of a vibration sensor.