A high frequency filter test fixture

Abstract

The application provides a high-frequency filter test tool, which comprises a left clamp, a right clamp, a base, an isolation ridge and probes; the left clamp and the right clamp are detachably fixed on two sides of the base, and the distance between the left clamp and the right clamp is adjustable; a stepped limiting cavity is formed between the left clamp and the right clamp, which is used for adapting to a lead bonding filter to be tested; the isolation ridge is arranged in the middle of the base, the top of the isolation ridge and the bottom of the stepped limiting cavity are located on the same plane; the left clamp and the right clamp are each provided with probes, the probes on each clamp are divided into signal probes and ground probes I, at least two ground probes I are arranged around each signal probe; more than one ground probe II is arranged on the isolation ridge; the ground probe II is in contact with the surface metal of the lead bonding filter to be tested. The application has high flexibility, can be adapted to devices of different sizes, and can also be used for small-batch testing of filters.

Description

Technical Field

[0001] This invention relates to the field of electronic communication technology, and more specifically to a high-frequency filter testing fixture. Background Technology

[0002] With the rapid development of radio frequency system-in-package (SIP) technology, miniaturized, high-frequency, and highly integrated radio frequency filters have become core components of radio frequency communication equipment. Among them, wire-bonded filters fabricated using LTCC technology are increasingly widely used in radio frequency SIP modules due to their outstanding advantages such as small size, excellent radio frequency performance, and strong integration adaptability. A typical assembly structure for this type of filter includes, for example... Figure 1 As shown, the upper surface of the circuit board or bare chip is coplanar with the bonding steps of the filter, which can significantly shorten the bonding wire length, effectively ensure high-frequency matching performance, and the operating frequency can be adapted to high-frequency scenarios up to 40GHz. It is a key passive component in current high-frequency radio frequency systems.

[0003] Currently, the conventional non-destructive testing methods for surface-mount filters mainly include contact spring testing, probe testing, and anisotropic conductive film testing. All three methods involve setting up corresponding conductive contact structures between the filter under test and the test circuit board. Elastic contact components such as contact springs, probes, and anisotropic conductive films are used to achieve electrical connection between the device and the test board, thus completing the non-destructive testing operation. However, each testing method has inherent technical limitations in high-frequency testing and structural adaptability.

[0004] Specifically, while the spring-loaded test method is simple in structure and highly adaptable, in high-frequency testing scenarios above 6GHz, the spring structure introduces significant transmission discontinuities, severely deteriorating high-frequency test parameters and leading to a substantial decrease in high-frequency test accuracy, thus failing to meet the testing requirements of high-frequency filters. Anisotropic conductive films possess excellent high-frequency transmission characteristics and high high-frequency test accuracy, but they impose stringent requirements on the electrode layout structure of the device under test (DUT), ensuring that the device electrodes are placed on the surface of the device's maximum contour, with no structural obstruction between the electrodes and the test board. However, the electrodes of LTCC wire-bonded filters are located at the stepped structure of the device, resulting in structural obstruction issues, making it impossible to use anisotropic conductive films for testing, severely limiting their applicability. Conventional probe testing methods can adapt to stepped electrode structures and meet the electrode contact testing requirements of wire-bonded filters, but this method also introduces transmission discontinuities during high-frequency testing, causing deterioration of test standing wave characteristics and easily leading to signal leakage, electromagnetic radiation, and other problems. Furthermore, electromagnetic coupling interference between probes severely affects the test accuracy of the filter's out-of-band rejection parameters, resulting in poor high-frequency test reliability.

[0005] For the structural characteristics and high-frequency testing requirements of LTCC wire-bonded filters, the mainstream testing method in the industry is microwave probe station testing. Microwave probe stations offer high testing accuracy, are adaptable to the stepped electrode structure of filters, and are compatible with various device sizes, making them the optimal testing equipment for this type of filter. However, this testing solution has significant limitations in industrialization. Manual probe station testing is extremely inefficient and cannot meet the needs of mass production testing. Automated probe stations can achieve automated batch testing, but the high cost of equipment procurement and maintenance significantly increases the mass production testing cost of LTCC wire-bonded filters, hindering the large-scale promotion and low-cost industrial application of the product.

[0006] In summary, current testing technologies for LTCC wire-bonded filters cannot simultaneously meet the requirements of high-frequency testing accuracy, adaptability to stepped electrode structures, low cost, and high efficiency. There is a lack of a testing solution that is adaptable to 40GHz high frequencies, compatible with any device size, offers high testing accuracy, low cost, and excellent testing efficiency. Therefore, there is an urgent need to develop a novel high-frequency testing solution for LTCC wire-bonded filters to address the numerous technical shortcomings and industrialization challenges of existing technologies. Summary of the Invention

[0007] In view of this, the present invention provides a high-frequency filter testing fixture that is highly flexible in use, can be adapted to devices of different sizes, and can also be used for small-batch testing of filters.

[0008] The technical solution adopted in this invention is as follows: A high-frequency filter testing fixture includes a left clamp, a right clamp, a base, an isolation ridge, and probes; The left and right clamps are detachably fixed on both sides of the base, and the distance between the left and right clamps is adjustable; a stepped limiting cavity is formed between the left and right clamps for adapting to the wire bonding filter under test; the isolation ridge is set in the middle of the base, and the top of the isolation ridge and the bottom of the stepped limiting cavity are on the same plane. The left and right clamps are each equipped with probes. The probes on each clamp are divided into signal probes and ground probes I. At least two ground probes I are provided around each signal probe. The isolation ridge is equipped with one or more ground probes II. The ground probes II are in contact with the surface metal of the wire-bonded filter under test.

[0009] Furthermore, the left fixture includes a fixture base, a test plate, a pin mold, and a connector; The test board is mounted on the upper surface of the fixture base, the connector is mounted on the side of the fixture base, and the connector pin is connected to the test board; the probe is embedded in the needle mold and mounted above the test board, with the bottom end of the probe contacting the top of the test board; The right clamp has the same structure as the left clamp.

[0010] Furthermore, the fixture base is made of metal, and the surface of the fixture base is provided with test plate mounting holes, pin mold mounting holes, and assembly positioning holes; the two sides of the fixture base are provided with waist-shaped fixture mounting holes; the side of the fixture base is provided with connector mounting holes and air coaxial cavity, and the middle of the fixture base is provided with transmission line groove; the air coaxial cavity is used to install connector pins, and the air coaxial cavity is connected to the transmission line groove.

[0011] Furthermore, a microstrip line is provided at the bottom of the test board, corresponding to the position of the transmission line slot. The characteristic impedance of the microstrip line is 50Ω. One end of the microstrip line is used to connect to the connector pin by soldering or gold strip soldering, and the other end is a metallized through hole connected to the metal disk at the top of the test board. A metal ground is provided around the microstrip line at the bottom of the test board and the metal disk at the top. The top metal disk and the metal ground do not contact each other. The top metal disk is used to contact the signal probe, and the metal ground contacts the ground probe I.

[0012] Furthermore, the needle mold is made of a non-metallic dielectric material; a limiting cavity is provided on one side of the needle mold, the limiting cavity has a stepped structure, the position of the step corresponds to the position of the electrode cavity of the wire-bonded filter under test; the depth of the step is 0-0.1 mm greater than the step height of the electrode of the wire-bonded filter under test; the depth of the limiting cavity is 0-0.2 mm greater than the thickness of the wire-bonded filter under test; a probe mounting hole is provided on the step, the height of the probe after being inserted into the probe mounting hole is 0.2-0.5 mm, and the distance between adjacent probe mounting holes is 0.4-1 mm.

[0013] Furthermore, the test fixture also includes an isolation ridge with a width of 0.5–2 mm.

[0014] Furthermore, the base is made of metal, and the base has left and right clamps on both sides to provide mounting positions.

[0015] Furthermore, the isolation ridge has an upper and lower split structure, used to clamp and fix the probe II.

[0016] Beneficial effects: 1. The present invention forms a stepped limiting cavity between the left and right clamps, which can be adapted to the wire bonding filter under test. At the same time, the probes set on the clamps are in the form of "ground-signal-ground", close to 50Ω, which solves the high-frequency test matching problem and the radiation leakage problem.

[0017] 2. This invention utilizes the waist-shaped mounting holes on the fixture base to adjust and adapt the spacing between the left and right fixtures, enabling the testing of filters of different sizes.

[0018] 3. The depth of the needle mold step in this invention is 0-0.1 mm greater than the height of the electrode step of the wire-bonded filter under test, which can prevent the filter from directly contacting the needle mold step and avoid damage to the filter; the distance between adjacent probe mounting holes is 0.4-1 mm. If the distance is too close, the processing accuracy will not be achieved. If the distance is too far, the test bandwidth will be limited, making it difficult to achieve wideband testing.

[0019] 4. The present invention also incorporates an isolation ridge, which helps to improve the isolation between the left and right clamp probes, reduce coupling, and improve the dynamic range of the test, especially the accuracy of the out-of-band suppression test of the filter. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a wire-bonded filter structure.

[0021] Figure 2 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 3 for Figure 2 Exploded view.

[0023] Figure 4 This is a schematic diagram of the left clamp structure.

[0024] Figure 5 for Figure 4 Exploded view.

[0025] Figure 6 This is a schematic diagram of the fixture base structure.

[0026] Figure 7 This is a schematic diagram of the fixture base from another perspective.

[0027] Figure 8 This is a schematic diagram of the front and back of the test board.

[0028] Figure 9 This is a schematic diagram of the needle mold structure.

[0029] Figure 10 This is a schematic diagram of the base structure.

[0030] Figure 11 This is a cross-sectional view of the filter during testing in conjunction with the tooling of this invention.

[0031] Among them, 1-left clamp, 2-right clamp, 3-base, 4-probe, 5-clamp base, 6-test board, 7-needle mold, 8-connector, 9-test board mounting hole, 10-needle mold mounting hole, 11-assembly positioning hole, 12-clamp mounting hole, 13-connector mounting hole, 14-air coaxial cavity, 15-transmission line groove, 16-microstrip line, 17-metallized through hole, 18-top metal disk, 19-limiting cavity, 20-step, 21-isolation ridge, 22-ground probe II, 23-wire bonding filter under test. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] This invention provides a high-frequency filter testing fixture, including a left clamp 1, a right clamp 2, a base 3, an isolation ridge 21, and a probe 4, as shown below. Figure 2 , Figure 3 As shown.

[0034] Left clamp 1 and right clamp 2 are detachably fixed to both sides of base 3, and the distance between left clamp 1 and right clamp 2 is adjustable; a stepped limiting cavity 19 is formed between left clamp 1 and right clamp 2 for fitting with the wire bonding filter 23 under test; each left clamp 1 and right clamp 2 is equipped with probes 4, and each probe 4 on the clamp is divided into a signal probe and a ground probe I, with at least two ground probes I around each signal probe. The center pin is the signal probe, and the two side pins are ground probes I, forming a "ground-signal-ground" structure.

[0035] The left clamp 1 and the right clamp 2 have the same structure. The explanation will take the left clamp 1 as an example. Figure 4 , Figure 5 As shown, the left fixture 1 includes a fixture base 5, a test plate 6, a needle mold 7, and a connector 8; the test plate 6 is mounted on the upper surface of the fixture base 5, the connector 8 is mounted on the side of the fixture base 5, and the connector pin is connected to the test plate 6; the probe 4 is embedded in the needle mold 7 and mounted above the test plate 6, with the bottom end of the probe 4 contacting the top of the test plate 6.

[0036] Specifically, such as Figure 6 , Figure 7 As shown, the fixture base 5 is made of metal, such as copper or aluminum. The surface of the fixture base 5 is provided with test plate mounting holes 9, pin mold mounting holes 10, and assembly positioning holes 11. The fixture base 5 has waist-shaped fixture mounting holes 12 on both sides, which facilitates the adjustment of the distance between the left fixture 1 and the right fixture 2 according to the filter size. The side of the fixture base 5 is provided with connector mounting holes 13 and air coaxial cavity 14. The middle of the fixture base 5 is provided with transmission line groove 15. The air coaxial cavity 14 is used to install connector pins, and the air coaxial cavity 14 is connected to the transmission line groove 15.

[0037] like Figure 8As shown, a microstrip line 16 is provided at the bottom of the test board 6, corresponding to the position of the transmission line slot 15. The characteristic impedance of the microstrip line 16 is 50Ω. One end of the microstrip line 16 (end A in the figure) is used to connect to the connector pin by soldering or gold strip soldering, and the other end (end B in the figure) is a metallized through-hole 17, which is connected to the top metal disk 18 of the test board 6. A metal ground is provided around the bottom microstrip line 16 and the top metal disk 18 of the test board 6. The top metal disk 18 and the metal ground do not contact each other. The top metal disk 18 is used to contact the signal probe, and the metal ground contacts the ground probe I.

[0038] like Figure 9 As shown, the needle mold 7 is made of a non-metallic dielectric material; a limiting cavity 19 is provided on one side of the needle mold 7 (the area where the filter is placed). The limiting cavity 19 has a structure with a step 20. The position of the step 20 corresponds to the position of the electrode cavity of the wire-bonded filter 23 under test. During testing, the step 20 is embedded in the filter electrode cavity; the depth of the step 20 is 0-0.1 mm greater than the height of the electrode step of the wire-bonded filter 23 under test. The depth of the step 20 refers to the height difference between the upper surface of the step 20 and the upper surface of the needle mold 7. In this embodiment, the depth of the step 20 is... The depth of the limiting cavity 19 is 0.2-0.5mm; the depth of the limiting cavity 19 is 0-0.2mm greater than the thickness of the lead-bonded filter 23 under test. The depth of the limiting cavity 19 refers to the height difference between the bottom plane of the cavity and the upper surface of the needle mold 7. During the test, it is necessary to ensure that the probe 4 is pressed in place to prevent the filter from touching the limiting cavity 19 first. The step 20 is provided with probe mounting holes. After the probe 4 is inserted into the probe mounting hole, the retractable part is exposed, with an exposed height of 0.2-0.5mm. The distance between adjacent probe mounting holes is 0.4-1mm to ensure a closer characteristic impedance.

[0039] like Figure 10 As shown, an isolation ridge 21 is disposed in the middle of the base 3. The width of the isolation ridge 21 is 0.5-2 mm, and one or more ground probes II 22 are provided on the isolation ridge 21. The ground probes II 22 are in metal contact with the surface of the wire-bonded filter 23 under test. The presence of the isolation ridge 21 and the ground probes II 22 helps to improve the isolation between the left clamp 1 and the right clamp 2 on both sides, eliminate mutual coupling, and is beneficial to improving the dynamic range of the test and improving the accuracy of out-of-band suppression test. Preferably, the isolation ridge 21 has an upper and lower split structure for clamping and fixing the ground probes II 22.

[0040] The base 3 is made of metal, and the isolation ridge 21 is located in the middle of the base 3. The top of the isolation ridge 21 is on the same plane as the bottom of the limiting cavity 19 of the needle mold 7. The base 3 provides mounting positions for left and right clamps on both sides.

[0041] like Figure 11 As shown, during the test, the wire-bonded filter 23 under test is placed upside down into the limiting cavity 19, and the signal probe is connected to the filter electrode and the top metal disk 18 of the test board 6.

[0042] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-frequency filter testing fixture, characterized in that, Includes left clamp, right clamp, base, isolation ridge and probe; The left and right clamps are detachably fixed on both sides of the base, and the distance between the left and right clamps is adjustable; a stepped limiting cavity is formed between the left and right clamps for adapting to the wire bonding filter under test; the isolation ridge is set in the middle of the base, and the top of the isolation ridge and the bottom of the stepped limiting cavity are on the same plane. The left and right clamps are each equipped with probes. The probes on each clamp are divided into signal probes and ground probes I. At least two ground probes I are provided around each signal probe. The isolation ridge is equipped with one or more ground probes II. The ground probes II are in contact with the surface metal of the wire-bonded filter under test.

2. The high-frequency filter testing fixture as described in claim 1, characterized in that, The left fixture includes a fixture base, a test plate, a pin mold, and a connector; The test board is mounted on the upper surface of the fixture base, the connector is mounted on the side of the fixture base, and the connector pin is connected to the test board; the probe is embedded in the needle mold and mounted above the test board, with the bottom end of the probe contacting the top of the test board; The right clamp has the same structure as the left clamp.

3. The high-frequency filter testing fixture as described in claim 2, characterized in that, The fixture base is made of metal. The surface of the fixture base is provided with test plate mounting holes, pin mold mounting holes, and assembly positioning holes. The two sides of the fixture base are provided with waist-shaped fixture mounting holes. The side of the fixture base is provided with connector mounting holes and air coaxial cavity. The middle of the fixture base is provided with transmission line groove. The air coaxial cavity is used to install connector pins and is connected to the transmission line groove.

4. The high-frequency filter testing fixture as described in claim 3, characterized in that, The test board has a microstrip line at the bottom, corresponding to the position of the transmission line slot. The microstrip line has a characteristic impedance of 50Ω. One end of the microstrip line is used to connect to the connector pin by soldering or gold strip soldering, and the other end is a metallized through hole connected to the metal disk at the top of the test board. A metal ground is provided around the microstrip line at the bottom of the test board and the metal disk at the top. The top metal disk and the metal ground do not contact each other. The top metal disk is used to contact the signal probe, and the metal ground contacts the ground probe I.

5. The high-frequency filter testing fixture as described in any one of claims 2-4, characterized in that, The needle mold is made of non-metallic dielectric material; a limiting cavity is provided on one side of the needle mold, the limiting cavity has a stepped structure, the position of the step corresponds to the position of the electrode cavity of the wire-bonded filter under test; the depth of the step is 0-0.1 mm greater than the step height of the electrode of the wire-bonded filter under test; the depth of the limiting cavity is 0-0.2 mm greater than the thickness of the wire-bonded filter under test; a probe mounting hole is provided on the step, the height of the probe after being inserted into the probe mounting hole is 0.2-0.5 mm, and the distance between adjacent probe mounting holes is 0.4-1 mm.

6. The high-frequency filter testing fixture as described in claim 5, characterized in that, The width of the isolation ridge is 0.5 to 2 mm.

7. The high-frequency filter testing fixture as described in claim 6, characterized in that, The base is made of metal, and there are two clamps on the left and right sides of the base to provide mounting positions.

8. The high-frequency filter testing fixture as described in claim 6, characterized in that, The isolation ridge is a split structure, used to clamp and fix the probe II.

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