CN206099918U - Thin film bulk acoustic wave filter packaging structure - Google Patents

Abstract

The utility model discloses a package structure of a thin film bulk acoustic wave filter, which comprises a substrate and a chip. Corresponding electrodes are arranged on the substrate and the chip. A film layer is bonded and fixed, and the film layer is close to the surface of the substrate and wraps the chip at the same time, forming a vacuum cavity between the chip and the substrate. The utility model can ensure that the chips are not polluted, realize miniaturization and improve processing efficiency.

Description

Thin film bulk acoustic wave filter packaging structure

technical field

The utility model relates to a film bulk acoustic wave filter (FBAR), in particular to a miniaturized packaging technology of a film bulk acoustic wave filter (FBAR), and belongs to the technical field of acoustic wave filters.

Background technique

At present, the miniaturized packaging of film bulk acoustic wave filter (FBAR) adopts the packaging form of potting resin packaging. In the future, there will be higher requirements for miniaturized packaging, and the potting resin is difficult to control the pollution problem. The thin-film bulk acoustic wave filter has high requirements on the working surface and cannot be polluted. Therefore, the packaging form of the potting resin is difficult to meet the needs of actual use. There is also a packaging structure that uses parallel welding of the ceramic shell, that is, a deep cavity structure is made on the shell, the bare chip is bonded in the deep cavity, and the lead wire is electrically connected to the external electrode, and then nitrogen gas is filled into the deep cavity to replace it. The air in it can finally close the deep cavity through the cover plate. Although such a packaging structure meets the requirement that the device cannot be polluted, there are at least two disadvantages in the following aspects: 1. It is difficult to miniaturize the device. At present, the smallest ceramic shell is 1.6mmX1.2mm and the thickness is more than 1mm. In the future mobile devices 2. The processing efficiency is low, because each device needs to be processed separately, and there is nitrogen and air replacement in order to keep the chip in a clean and non-polluted environment. Therefore, the encapsulation efficiency is relatively low.

Utility model content

In view of the above-mentioned deficiencies in the prior art, the purpose of this utility model is to provide a film bulk acoustic wave filter packaging structure that ensures that the chip is not polluted and can realize miniaturization.

In order to achieve the above object, the technical scheme adopted by the utility model is as follows:

A packaging structure of a thin film bulk acoustic wave filter, including a substrate and a chip. Corresponding electrodes are arranged on the substrate and the chip. The electrode of the chip is correspondingly connected to the electrode of the substrate by gold balls through flip-chip welding, and a film is bonded and fixed on the surface of the substrate. The film layer is close to the surface of the substrate and wraps the chip at the same time, forming a vacuum cavity between the chip and the substrate.

The film layer is an adhesive film and a resin film.

Compared with the prior art, the utility model has the following advantages:

1. The utility model uses flip-chip welding to weld the bare chip of the surface acoustic wave filter on the substrate, and attaches the resin film or adhesive film to the substrate to wrap the bare chip through vacuum pressure. Through such means, the inside of the device Two parts isolated from the outside are formed, so as to protect the surface of the bare chip from being polluted and the sealing effect protects the working surface of the surface acoustic wave device, so that the device can work normally.

2. The utility model can process multiple devices on the same substrate at one time, and finally cut them into individual devices, so the packaging efficiency is significantly improved compared with the traditional single packaging process.

3. The utility model abandons the ceramic shell in the original technology, can realize the direct packaging of the bare chip, the packaging efficiency (chip area/packaging area) can reach more than 50%, and the thickness can be controlled below 0.6mm, realizing Device miniaturization.

Description of drawings

Fig. 1 - structural representation of the utility model.

Fig. 2 - The shape diagram of the substrate before cutting in this packaging method.

Figure 3 - Exploded view of adhesive film after encapsulation.

detailed description

The utility model is described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Fig. 1 and Fig. 3, it can be seen from the figures that the packaging structure of the thin film bulk acoustic wave filter of the present invention includes a substrate 1 and a chip 2, and corresponding electrodes are arranged on the substrate and the chip, and the chip electrodes are flip-chip welded. The process is to connect the gold ball 3 to the substrate electrode correspondingly. A film layer 4 is glued and fixed on the surface of the substrate 1 , and the film layer 4 is closely attached to the surface of the substrate 1 and wraps the chip 2 at the same time, forming a vacuum chamber 5 between the chip 2 and the substrate 1 .

The packaging method of the thin film bulk acoustic wave filter of the present invention, the thin film bulk acoustic wave filter has the aforementioned packaging structure, and the specific packaging steps are as follows:

1) Divide the chip packaging area on the substrate according to the number of chips to be packaged, and each area corresponds to a chip to be packaged; set the substrate electrode corresponding to the chip electrode in each area; the chip packaging area is arranged in a matrix;

2) Weld the electrodes on the chips to be packaged to the corresponding electrodes in the corresponding areas of the substrate through the flip-chip welding process;

3) Attach the protective film on the substrate and wrap all the chips through the vacuum film bonding process, forming a vacuum cavity between each chip and the substrate;

4) The protective film is bonded and cured by heating, so that the protective film is fixedly connected to the substrate and the chip respectively; the product form obtained in this step is shown in Figure 2;

5) Cutting the substrate according to the packaging area to obtain cutting units. Each cutting unit is composed of a substrate corresponding to the packaging area, a chip on it and a protective film. The cutting unit constitutes a thin-film bulk acoustic wave filter.

The material of the film layer in the utility model is an adhesive film and a resin film. This kind of membrane material is heat-curable. At a certain temperature, the material softens into a "jelly-like" shape, and can be shaped according to the designed shape under the action of pressure; further increasing the temperature, the material will gradually solidify and maintain It is precisely based on this feature that the shape after molding can be used in this packaging process to form this packaging structure.

The bare chip of the surface acoustic wave device of the utility model is flip-chip welded on the substrate by gold balls to form a stepped structure, there is a gap between the bottom of the step and the substrate, and the vacuum film sticking process is used to make the protective film form a wrapping layer along the upper surface of the device , after the film is pasted, the gap forms a vacuum cavity.

Since the working area of the surface acoustic wave device cannot be polluted, it is necessary to protect the cavity formed after the device is flip-chip soldered. The utility model adopts the protective film for encapsulation and uses it as a protective layer to prevent subsequent encapsulation materials from invading the cavity. The bare chip of the surface acoustic wave filter is welded on the substrate by flip-chip welding technology, and the protective film is mounted on the substrate by vacuum pressure and wraps the bare chip, thereby protecting the surface of the bare chip from contamination and sealing effect. Since the film attachment is carried out in a vacuum environment, the moisture content of the device can be guaranteed.

The above-mentioned embodiments of the utility model are only examples for illustrating the utility model, rather than limiting the implementation of the utility model. For those of ordinary skill in the art, other variations and modifications in various forms can be made on the basis of the above description. All the implementation manners cannot be exhaustively listed here. All obvious changes or variations derived from the technical solutions of the utility model are still within the scope of protection of the utility model.

Claims (2)

1. a kind of thin-film bulk acoustic wave filter encapsulating structure, including substrate and chip, substrate and chip are provided with corresponding electrode, It is characterized in that：The chip electrode, is adhesively fixed in substrate surface by gold goal connection corresponding with electrode of substrate by flip chip bonding There is a film layer, the film layer is close to substrate surface and while wrap chip, and vacuum chamber is formed between chip and substrate.

2. thin-film bulk acoustic wave filter encapsulating structure according to claim 1, it is characterised in that：The film layer is bonding die film And resin film.