Modular socket fixture full front end test method

Abstract

The present application relates to the field of LGA or LCC package module test, in order to realize accurate test of the front-end circuit of the fixture, a complete front-end test method of module socket fixture is provided, a special test PCB is used, and a vector network analyzer is used, without welding cable line, the testable position is from the previous fixture bottom plate pad to the module pad position, and the whole front-end network of the module pad, the gold needle, the fixture bottom plate pad, the fixture bottom plate common passage and the test radio frequency line can be completely and accurately tested.

Description

Technical Field

[0001] This invention relates to the field of LGA or LCC packaged module testing, specifically a method for testing the complete front end of a module socket fixture. Background Technology

[0002] In the production testing phase of LGA or LCC packaged modules, the industry commonly uses the following testing method: the module is fixed to the base plate of the fixture using a socket fixture, and the gold pins inside the socket connect the module pads to the test pads of the fixture base plate, thereby simulating the electrical performance of the module after it is actually soldered to the base plate, and thus completing various tests of the module.

[0003] However, for larger RF pads, the above-mentioned test method for gold pin connections can lead to impedance mismatch due to the abrupt change in shape between the pad and the pin. For R&D personnel, this mismatch is unpredictable and unmeasurable.

[0004] During production line testing, the impedance of the gold pins cannot be accurately measured, making it impossible to effectively assess their usage. Currently, the industry can only estimate pin usage based on production volume experience. For example, the lifespan of RF gold pins is estimated at 4k product testing cycles, while that of other signal gold pins is estimated at 8k product testing cycles.

[0005] In addition, the industry currently mainly uses the following two methods for production line loss testing: A. Gold Board Method: This method uses laboratory power test results as the standard, recording the difference between the production line power test value and the laboratory test value as the production line test fixture line loss. However, in actual testing, power test results vary due to factors such as the current single board temperature, which leads to different temperature compensation and frequency compensation parameters being applied. Furthermore, the environmental conditions and operational procedures for laboratory power testing are difficult to maintain strictly. This method is highly dependent on the operation of laboratory R&D professionals, is time-consuming, and its accuracy is difficult to guarantee.

[0006] B. Power Meter Method: This method uses a signal generator to output a signal with a defined frequency and power, then uses a power meter to measure the power at the test point and calculate the path loss. This method can accurately measure the line loss of accessible paths and does not require professional operation. However, it cannot effectively measure physical inaccessible test areas, such as metal pins or the front end of tooling base plates. Summary of the Invention

[0007] To achieve accurate testing of the front-end circuit of the fixture, this invention provides a complete front-end testing method for module socket fixtures.

[0008] The technical solution adopted by the present invention to solve the above problems is: A complete front-end testing method for module socket fixtures, including: Step 1: Provide a dedicated test PCB. The dimensions of the dedicated test PCB are consistent with the length and width of the module under test. Only the RF signal pin and GND pin are retained on the dedicated test PCB, and the remaining signal pins are set to NC state. The RF signal lines on the dedicated test PCB are routed with a 50Ω impedance and reliably grounded. The dedicated test PCB is equipped with an IPEX test socket. Step 2: Connect the RF line connected to port 1 of the vector network analyzer to the dedicated test PCB through the IPEX test socket. Perform calibration compensation on the extension line of port 1 of the vector network analyzer. Calibrate and compensate all the test lines of port 1, the IPEX test socket of the dedicated test PCB, the traces of the dedicated test PCB, and the RF signal pads of the dedicated test PCB to the electrical length of the extension line of port 1. At the same time, port 2 remains unconnected to the RF line. Step 3: Place the calibrated and compensated dedicated test PCB into the fixture socket, press it to the fixture base plate, avoid the RF line area and keep it pressed flat, and connect port 2 normally to the RF socket on the fixture base plate. Step 4: Perform S11 impedance and S21 insertion loss tests using a vector network analyzer to complete the front-end test of the module socket fixture.

[0009] Furthermore, the dedicated test PCB has two or four layers.

[0010] Furthermore, it also includes step 5, evaluating the usage status of the clamp needle based on the insertion loss test results of S21, in order to determine whether the needle needs to be replaced.

[0011] Furthermore, if the S21 impedance does not exceed the initial calibration value, it is determined that the fixture path is normal, and the insertion loss at each frequency point is recorded as the station line loss in the test tool.

[0012] Furthermore, the module under test is an LGA packaged module or an LCC packaged module.

[0013] The advantages of this invention compared to the prior art are: Using a dedicated test PCB and a vector network analyzer, the testable position can be moved from the previous fixture base plate pads to the module pads without the need for cable soldering. This allows for complete testing of the entire front-end network, from the module pads, pins, fixture base plate pads, to the fixture base plate common path, and the test RF lines.

[0014] The method of this invention only requires a vector network analyzer, which simplifies the use of the instrument compared to the power meter method.

[0015] The method of this invention provides a concrete test result for the condition of production line fixtures, especially the condition of gold needles. Based on this test result, the condition of gold needles can be effectively monitored, which helps to optimize costs. Attached Figure Description

[0016] Figure 1 Flowchart of the complete front-end testing method for the module socket fixture; Figure 2 This is a schematic diagram of the dedicated test PCB interface design in the embodiment. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] This invention designs a dedicated test PCB corresponding to the size of the module under test. This PCB retains only the RF signal pins and GND pins, setting the remaining signal pins to NC state. The RF signal lines are led out to the IPEX RF socket with a 50Ω impedance, thus physically replicating the contact interface between the module pads and the socket pins. During testing, the RF line of port one of the vector network analyzer is connected to the test PCB through the IPEX socket, and the extension line calibration of port one is performed. This calibration compensates the entire electrical length of the test line, IPEX socket, PCB traces, and PCB pads to the instrument reference plane, causing the test reference plane of the vector network analyzer to move from the instrument port to the surface of the RF pads on the test PCB. At this time, the test PCB is placed in the fixture socket and pressed. The S11 (impedance reflection) and S21 (insertion loss) parameters measured by the vector network analyzer completely reflect the RF characteristics of the entire front-end network from the module pads, through the pin contacts, the fixture base plate pads, the internal traces of the base plate, to the RF output port of the base plate common terminal. Based on transmission line theory, S11 reveals the reflection loss caused by impedance discontinuities, while S21 characterizes the insertion loss of the entire link. By comparing the test values ​​with the design values ​​or initial calibration values, the contact impedance changes, wear levels, and line loss of the entire front-end path of the gold pin can be quantitatively evaluated, thus providing a direct and accurate measurement basis for gold pin replacement and line loss compensation on the production line.

[0019] like Figure 1 As shown, the complete front-end testing method for the module socket fixture includes: Step 1: Provide a dedicated test PCB. The dimensions of the dedicated test PCB are the same as the length and width of the module under test. Only the RF signal pins and GND pins are retained on the dedicated test PCB; the remaining signal pins are set to NC state. The RF signal lines on the dedicated test PCB are routed with a 50Ω impedance and reliably grounded. The dedicated test PCB is equipped with an IPEX test socket. The interface design diagram is shown below. Figure 2 As shown.

[0020] Furthermore, to reduce costs, the number of layers on the dedicated test PCB can be appropriately reduced, such as by setting it to two or four layers. It is only necessary to ensure that the impedance of its RF traces, test sockets, and bottom pads is controlled to around 50 ohms. In this embodiment, to provide better impedance control for the module pad pins and IPEX test sockets, the dedicated test PCB uses a four-layer through-hole PCB.

[0021] Step 2: Connect the RF line connected to port 1 of the vector network analyzer to the dedicated test PCB through the IPEX test socket. Perform extension line calibration compensation on port 1 of the vector network analyzer. Calibrate and compensate all test lines of port 1, IPEX test socket of the dedicated test PCB, traces of the dedicated test PCB, and RF signal pads of the dedicated test PCB to the electrical length of the extension line of port 1. Keep port 2 unconnected to the RF line.

[0022] This step includes the port's test leads, the IPEX test sockets on the test PCB, the test PCB traces, and the RF signal pads on the test PCB in the extension compensation of the port's electrical length. This lays the foundation for accurate subsequent measurements of the complete front-end path loss from the module pad contact, gold pins, baseboard pads, baseboard common path, and RF lines.

[0023] Step 3: Place the calibrated and compensated dedicated test PCB into the fixture socket, press it to the fixture base plate, avoid the RF line area and keep it pressed flat, and then connect port 2 normally to the RF socket on the fixture base plate. Step 4: Perform S11 impedance and S21 insertion loss tests using a vector network analyzer to complete the front-end test of the module socket fixture.

[0024] During testing, if the S11 impedance does not exceed the initial calibration value (e.g., 1 dB), the fixture path is considered normal, and the insertion loss at each frequency point is recorded as the station line loss in the testing tool. The initial calibration value can be set based on the test results from the R&D laboratory.

[0025] Furthermore, step 5 is included: assessing the usage status of the fixture pins based on the S21 insertion loss test results to determine whether the pins need to be replaced. The S21 insertion loss test results provide a quantitative result of the pin usage status. Compared with the previous method of estimating service life based solely on production experience, this can significantly reduce the cost waste caused by prematurely replacing intact pins. It can also avoid the risk of defective products flowing out due to excessive wear of pins and failure to replace them in time. This effectively improves the stability and reliability of production line testing, while reducing the overall operation and maintenance costs of the testing process.

[0026] This method can be used for all modules except LGA or LCC packaged modules that use socket testing. A test PCB with the same size as the module under test can be designed, and a vector network analyzer can be used to test the complete front-end network from the module pad contacts to the fixture base plate and the test RF lines.

Claims

1. A complete front-end testing method for module socket fixtures, characterized in that, include: Step 1: Provide a dedicated test PCB. The dimensions of the dedicated test PCB are consistent with the length and width of the module under test. Only the RF signal pin and GND pin are retained on the dedicated test PCB, and the remaining signal pins are set to NC state. The RF signal lines on the dedicated test PCB are routed with a 50Ω impedance and reliably grounded. The dedicated test PCB is equipped with an IPEX test socket. Step 2: Connect the RF line connected to port 1 of the vector network analyzer to the dedicated test PCB through the IPEX test socket. Perform calibration compensation on the extension line of port 1 of the vector network analyzer. Calibrate and compensate all the test lines of port 1, the IPEX test socket of the dedicated test PCB, the traces of the dedicated test PCB, and the RF signal pads of the dedicated test PCB to the electrical length of the extension line of port 1. At the same time, port 2 remains unconnected to the RF line. Step 3: Place the calibrated and compensated dedicated test PCB into the fixture socket, press it to the fixture base plate, avoid the RF line area and keep it pressed flat, and connect port 2 normally to the RF socket on the fixture base plate. Step 4: Perform S11 impedance and S21 insertion loss tests using a vector network analyzer to complete the front-end test of the module socket fixture.

2. The complete front-end testing method for module socket fixtures according to claim 1, characterized in that, The dedicated test PCB has two or four layers.

3. The complete front-end testing method for module socket fixtures according to claim 1, characterized in that, It also includes step 5, evaluating the usage status of the clamp gold needle based on the insertion loss test results of S21, in order to determine whether the gold needle needs to be replaced.

4. The complete front-end testing method for module socket fixtures according to claim 1, characterized in that, If the S21 impedance does not exceed the initial calibration value, the fixture path is considered normal, and the insertion loss at each frequency point is recorded as the station line loss in the test tool.

5. The complete front-end testing method for module socket fixtures according to any one of claims 1-4, characterized in that, The module under test is an LGA packaged module or an LCC packaged module.

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