On-chip antenna structure of millimeter wave radar chip and adjusting method thereof

Abstract

The invention provides an on-chip antenna structure of a millimeter-wave radar chip and an adjusting method of the on-chip antenna structure, and belongs to the technical field of on-chip antennas. The on-chip antenna structure comprises a built-in air pressure cavity, a metal containing cavity pipeline, low-melting-point metal and a first lead, the built-in air pressure cavity is communicated with one end of the metal containing cavity pipeline, the direction of the metal containing cavity pipeline is horizontal, an external air pressure adjusting outlet is formed in the other end of the metal containing cavity pipeline, and the low-melting-point metal is located in the built-in air pressure cavity and the metal containing cavity pipeline. And the low-melting-point metal is connected with the first lead wire and further connected with the radio frequency unit of the millimeter wave radar chip. Through the scheme of the invention, the shape of the on-chip antenna can be adjusted in the chip preparation process, individual radio frequency parameters are met, multiple chip tape-out is not needed, the cost of chip customization is greatly reduced, and the efficiency and effect of millimeter wave radar on-chip antenna customization are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of on-chip antennas, and in particular relates to an on-chip antenna structure of a millimeter-wave radar chip and an adjustment method thereof. Background Art

[0002] With the development of new energy vehicles, millimeter-wave radar technology has been widely used. Millimeter-wave radar chips are mainly used in front radar, corner radar, and cabin personnel status monitoring for vehicle external perception. At the same time, there are solutions to integrate the antenna part of the millimeter-wave radar chip into the chip, further improving the integration of the millimeter-wave radar chip.

[0003] In the existing technology, due to the different application scenarios of front radar and corner radar, there are certain differences in parameter requirements for their illumination distance, angle, resolution, etc. Usually, front radar and corner radar generally use different radar RF chips to better match the usage requirements of different scenarios and the balance between performance and cost. There are also solutions that use the same millimeter-wave radar chip and adjust the RF parameters of the antenna by changing the shape of the antenna to meet the application requirements of different scenarios such as front radar and corner radar.

[0004] However, with the development of technology and the emergence of on-chip antenna technology, the shape of the antenna is fixed when the millimeter-wave radar chip leaves the factory. It is impossible to change the RF parameters by adjusting the shape of the antenna on the PCB board, making it difficult to meet the application requirements of multiple scenarios. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention proposes an on-chip antenna structure of a millimeter-wave radar chip and an adjustment method thereof. This solution provides a method for adjusting the length and shape of the on-chip antenna during the chip preparation process, which can not only meet the parameter adjustment requirements for changes in scene applications such as front radar and corner radar, but also can fine-tune the shape of the antenna in batches according to the differences in the actual position layout of different vehicle models.

[0006] The technical solution proposed by the present invention is as follows:

[0007] On the one hand, the present invention proposes an on-chip antenna structure of a millimeter-wave radar chip, comprising a built-in air pressure cavity, a metal cavity pipe, a low-melting-point metal and a first lead; the built-in air pressure cavity is connected to one end of the metal cavity pipe, the direction of the metal cavity pipe is horizontal, and the other end forms an external air pressure adjustment outlet, and the external air pressure adjustment outlet is connected to the external atmosphere before the antenna adjustment is completed; the low-melting-point metal is located inside the built-in air pressure cavity and the metal cavity pipe to form a metal antenna; the built-in air pressure cavity has a cavity at one end away from the metal cavity pipe, and the metal cavity pipe also has a cavity at one end at the external air pressure adjustment outlet, and the cavity at the outlet is connected to the external atmosphere before the antenna adjustment is completed; the millimeter-wave radar chip includes a radio frequency unit, the low-melting-point metal in the built-in air pressure cavity is connected to the first lead, and the first lead is connected to the radio frequency unit of the millimeter-wave radar chip through a solder ball; the melting point of the low-melting-point metal is lower than the melting point of the solder ball.

[0008] On the other hand, the present invention provides a method for adjusting the antenna length of the above-mentioned on-chip antenna structure, comprising:

[0009] The on-chip antenna structure is prepared, and the required antenna length is determined based on the radio frequency parameters required by the millimeter wave radar chip;

[0010] The on-chip antenna structure is placed in a sealed cavity, and a hot air flow is introduced into the cavity to adjust the temperature inside the cavity to between the melting point of the low-melting-point metal and the melting point of the solder ball, so that the low-melting-point metal is melted into a liquid state;

[0011] Ensure that the external air pressure adjustment outlet is not blocked, connect the closed cavity to the air pressure regulating device, and adjust the air pressure in the closed cavity through the air pressure regulating device to make the liquid low-melting-point metal extend or shorten along the metal cavity pipeline to the required antenna length; when the low-melting-point metal stops extending or shortening, keep the external air pressure unchanged, lower the temperature inside the cavity to below the melting point of the solder ball, turn the low-melting-point metal into a solid state, and at the same time block the external air pressure adjustment outlet, so as to obtain the on-chip antenna structure for the millimeter-wave radar chip.

[0012] The present invention has the following beneficial effects:

[0013] Through the scheme described in the present invention, the length and shape of the on-chip chip antenna can be dynamically adjusted in the early stage of chip manufacturing, so that the index parameters of the antenna can be dynamically adjusted during the chip manufacturing process, providing a flexible and changeable production method for millimeter-wave radar chips with on-chip antennas according to different needs, improving production efficiency, and meeting the needs of adjustable chip RF parameters in different scene applications. While meeting personalized RF parameters, the present invention does not require multiple chip tape-outs, greatly reducing the cost of chip customization and improving the efficiency and effect of customized millimeter-wave radar on-chip antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the on-chip antenna structure of the millimeter-wave radar chip of the present invention;

[0015] Figure 2 It is a top perspective view of the on-chip antenna structure of the millimeter-wave radar chip of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0017] The present invention provides an on-chip antenna structure of a millimeter wave radar chip, including a built-in air pressure cavity 201 , a metal cavity pipe 202 , a low melting point metal 203 and an antenna lead 207 .

[0018] The on-chip antenna structure is implemented on the millimeter-wave radar chip 1; the millimeter-wave radar chip 1 is connected to the PCB substrate through solder balls; the built-in air pressure cavity 201 is connected to the metal cavity pipe 202, and contains a low-melting-point metal 203 inside, and the low-melting-point metal 203 is connected to the millimeter-wave radar chip 1 through the antenna lead 207 and the solder ball.

[0019] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] An on-chip antenna structure of a millimeter wave radar chip, such as Figure 1 As shown, it is located above the radar chip and includes a built-in air pressure cavity 201, a metal cavity pipe 202, a low melting point metal 203, an external air pressure adjustment outlet 204, an antenna package 205, a metal substrate 206, an antenna lead 207, and a solder ball 208.

[0021] The millimeter wave radar chip 1, including a computing unit, a radio frequency unit, etc., is connected to the PCB substrate through solder balls.

[0022] In the on-chip antenna structure, the built-in air pressure cavity 201 and the metal cavity pipe 202 are connected to each other. Figure 2As shown. The metal cavity pipe 202 is connected to the external atmosphere through the external air pressure adjustment outlet 204. The built-in air pressure cavity 201 and the metal cavity pipe 202 contain a low-melting-point metal 203, and a cavity is left at one end of the built-in air pressure cavity 201 away from the metal cavity pipe 202, and the cavity is sealed by the low-melting-point metal 203; the metal cavity pipe 202 also has a cavity at one end at the external air pressure adjustment outlet 204, and the cavity is connected to the outside. The low-melting-point metal 203 forms a metal antenna in the built-in air pressure cavity 201 and the metal cavity pipe 202, and the part of the low-melting-point metal 203 in the built-in air pressure cavity 201 is connected to the antenna lead 207, and the antenna lead 207 is connected to the RF unit circuit of the radar chip 1 through the solder ball 208.

[0023] The antenna package 205 may be made of non-shielding materials such as engineering plastics. The metal substrate 206 is placed between the antenna package 205 and the radar chip as the RF reference ground of the antenna. At the same time, the metal substrate 206 is connected to the solder ball 208 through the antenna lead 207, and then connected to the GND node of the radar chip 1 below. The antenna lead 207 connected to the metal substrate 206 and the antenna lead 207 connected to the low melting point metal 203 are not the same lead, and are independent of each other.

[0024] The melting point of the low melting point metal 203 is lower than the melting point of the tin ball. In this embodiment, a tin-bismuth alloy (melting point is about 138° C.) can be selected, or a metal alloy containing low melting point materials such as tin, bismuth, and lead can be selected to facilitate adjustment of the antenna length.

[0025] The metal cavity pipe 202 can be a straight pipe or a multi-branch pipe, depending on the form of the required antenna. The multi-branch pipe is composed of multiple branch pipes, all of which are converged at one end and connected to the built-in air pressure cavity 201, and each branch pipe forms an external air pressure adjustment outlet 204 at the other end. Figure 2 shown.

[0026] Furthermore, during the preparation of the above chip, an antenna length adjustment process is added, and by controlling the length and shape of the metal on a specific path, the antenna performance index required by the radar chip below is adjusted to be consistent. The adjustment method of the above-mentioned millimeter-wave radar chip with adjustable on-chip antenna is as follows:

[0027] Based on the RF parameters required by the millimeter wave radar chip, the chip's on-chip antenna is simulated, designed, and measured to adjust, and finally the required antenna length is determined; the RF parameters include transmit power, receive power, operating frequency, etc.;

[0028] Assume the melting point of the low melting point metal is T A , the melting point of the solder ball is T BIn the antenna preparation process, after the above-mentioned on-chip antenna structure is initially prepared, the on-chip antenna structure is placed in a high-temperature box of a closed reflow furnace, and the temperature in the furnace is set to T A1 , T B <T A1 <T A The reflow furnace heats the on-chip antenna structure with hot air, so that the low-melting-point metal melts but the solder ball does not melt; at this time, the cavity pressure of the built-in air pressure cavity 201 is P A0 ;

[0029] The reflow furnace is equipped with an air pump that can adjust the air pressure in the furnace. When the metal inside is molten, ensure that the external air pressure adjustment outlet of the pipeline where the part to be adjusted is not blocked. Use the air pump to evacuate or inflate the furnace to adjust the air pressure in the furnace to P. BS1 At this time, since the external air pressure adjustment outlet 204 is connected to the external atmosphere, the air pressure at the external air pressure adjustment outlet 204 is also P BS1 ;

[0030] P A0 , P BS1 Due to the influence of the air pressure difference, the displacement of the low melting point metal 203 inside the metal cavity pipe 202 changes:

[0031] (1) When P A0 >P BS1 When the liquid low melting point metal 203 extends along the metal cavity pipe 202 toward the outlet side, the cavity pressure of the built-in gas pressure cavity 201 changes from P A0 Reduced to P A1 , when P A1 =P BS1 When , the liquid metal stops moving;

[0032] At this time, keep P BS1 Keep unchanged and lower the temperature to the melting point of solder ball T B Next, the liquid low melting point metal 203 is converted into a solid state with a fixed shape, and at the same time, the external air pressure adjustment outlet 204 is blocked, so that the air pressure in the two cavities of the built-in air pressure cavity 201 and the metal cavity pipe 202 remains consistent;

[0033] (2) When P A0 <P BS1 When the liquid low melting point metal 203 is shortened along the metal cavity pipe 202 toward the side of the built-in air pressure cavity 201, the cavity pressure of the built-in air pressure cavity 201 changes from P A0 Increase to P A2 , when P A2 =P BS1 When , the liquid metal stops moving;

[0034] By adjusting P BS1The size of P can make the liquid metal reach the required antenna length; after the liquid metal finishes moving, keep P BS1 Keep unchanged and lower the temperature to the melting point of solder ball T B Next, the liquid low melting point metal 203 turns into a solid state with a fixed shape, and at the same time blocks the external air pressure adjustment outlet 204, so that the air pressure in the two cavities of the built-in air pressure cavity 201 and the metal cavity pipe 202 remains consistent.

[0035] Through the above method, the length of the antenna inside the on-chip antenna unit can be adjusted (the shape is placed in advance according to a preset pipeline and is not limited to a single straight line shape), thereby fine-tuning the RF parameters of the antenna.

[0036] For the multi-branch metal cavity pipe 202, the metal length in each branch pipe can be adjusted in sequence by the above method, thereby completing the length adjustment of the multi-branch antenna.

[0037] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An on-chip antenna structure of a millimeter-wave radar chip, characterized in that: It includes a built-in air pressure cavity, a metal cavity pipeline, a low melting point metal and a first lead; The built-in air pressure cavity is connected to one end of the metal cavity pipe, the metal cavity pipe is horizontal, and the other end forms an external air pressure adjustment outlet, which is connected to the external atmosphere before the antenna adjustment is completed; The low melting point metal is located inside the built-in air pressure cavity and the metal cavity pipe to form a metal antenna; the built-in air pressure cavity has a cavity at one end away from the metal cavity pipe, and the metal cavity pipe also has a cavity at one end at the external air pressure adjustment outlet, and the cavity at the outlet is connected to the external atmosphere before the antenna adjustment is completed; The millimeter wave radar chip includes a radio frequency unit, and the low melting point metal in the built-in air pressure cavity is connected to the first lead, and the first lead is used to connect the radio frequency unit of the millimeter wave radar chip through a solder ball; The melting point of the low melting point metal is lower than the melting point of the solder ball.

2. The on-chip antenna structure according to claim 1, characterized in that: The low melting point metal is a metal having a melting point lower than 230°C.

3. The on-chip antenna structure according to claim 1, characterized in that: The metal cavity pipeline is composed of a plurality of branch pipelines, one end of each branch pipeline is converged and communicated with the built-in air pressure cavity, and the other end forms an external air pressure adjustment outlet.

4. The on-chip antenna structure according to claim 1, characterized in that: The on-chip antenna structure also includes an antenna package, a metal substrate and a second lead. The antenna package is used to encapsulate a built-in air pressure cavity, a metal cavity pipe, a low-melting-point metal and a first lead. The metal substrate is located between the antenna package and the millimeter-wave radar chip. The metal substrate is connected to the GND node of the millimeter-wave radar chip through the second lead, and a solder ball is provided at the connection for fixation.

5. The on-chip antenna structure according to claim 4, characterized in that: The antenna package is made of engineering plastics.

6. The on-chip antenna structure according to claim 1, characterized in that: The external air pressure adjustment outlet is closed after the antenna adjustment is completed.

7. A method for adjusting the antenna length of the on-chip antenna structure according to claim 1, characterized in that: Methods include: The on-chip antenna structure is prepared, and the required antenna length is determined based on the radio frequency parameters required by the millimeter wave radar chip; The on-chip antenna structure is placed in a sealed cavity, and a hot air flow is introduced into the cavity to adjust the temperature inside the cavity to between the melting point of the low-melting-point metal and the melting point of the solder ball, so that the low-melting-point metal is melted into a liquid state; Ensure that the external air pressure adjustment outlet is not blocked, connect the closed cavity to the air pressure regulating device, and adjust the air pressure in the closed cavity through the air pressure regulating device to make the liquid low-melting-point metal extend or shorten along the metal cavity pipeline to the required antenna length; when the low-melting-point metal stops extending or shortening, keep the external air pressure unchanged, lower the temperature inside the cavity to below the melting point of the solder ball, turn the low-melting-point metal into a solid state, and at the same time block the external air pressure adjustment outlet, so as to obtain the on-chip antenna structure for the millimeter-wave radar chip.

8. The antenna length adjustment method according to claim 7, characterized in that: If the metal cavity pipeline is composed of a plurality of branch pipelines, the length of the low-melting-point metal in each branch pipeline is adjusted in turn, and other branch pipelines are blocked during the adjustment process.

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