Method for testing condensation in electronic components

Abstract

To provide a condensation test method for electronic components that can reliably detect the occurrence of Ag-ECM and can reproduce condensation loads under various test environments of the customer. [Solution] The condensation test method for the electronic component 5 includes a base selection step of selecting a base 17 from among a plurality of bases having different heat capacities, a step of setting the selected base 17 on a breathable shelf 16 placed inside the test chamber 12, a step of setting the electronic component 5 on the base 17, a step of covering the base 17 and the electronic component 5 with a cover member 21, and a step of controlling the temperature inside the test chamber 12.

Description

Technical Field

[0001] The present invention relates to a dew condensation test method for electronic components.

Background Art

[0002] Conventionally, a dew condensation test method for electronic components has been known. For example, in Patent Document 1, a test method is disclosed in which a sample is placed on a sample stage in a test tank and cooled, and air whose temperature and humidity are adjusted to predetermined conditions is supplied to the test tank while maintaining a constant temperature, and dew condensation is caused to occur on the surface of the sample due to the temperature difference between the supplied air and the sample. In this test method, predetermined characteristics are tested for a sample in a state where dew condensation has occurred on the surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the evaluation of electronic components by customers, migration may occur. For example, in the evaluation of an electronic component having a conductive resin layer containing an Ag filler on an external electrode, Ag electrochemical migration (hereinafter referred to as "Ag-ECM") may occur and Ag may appear on the surface of the electronic component.

[0005] In that case, based on information from the customer, an electronic component manufacturer conducts a reproduction test of Ag-ECM. In that test, a substrate on which an electronic component is mounted is set in a test tank capable of controlling temperature and humidity, and a temperature and humidity cycle test operation is performed while applying a voltage. However, even when an electronic component manufacturer tests the same lot of electronic components under the same test conditions as the customer, Ag-ECM may not be reproduced.

[0006] Ag-ECM is a phenomenon in which the dissolution (ionization, oxidation reaction) of the anode metal begins due to the electric field the moment a water droplet path is formed between electrodes due to condensation. Therefore, the most important intermediate indicator in Ag-ECM testing is the amount of condensation.

[0007] However, conventional technology has not been able to establish an effective method for quantitatively determining the amount of condensation during this test, nor has it been possible to confirm the stability of the test. This is because, although condensation sensors exist commercially and are actually used in tests of condensation environments, their detection limit is very low, making it impossible to quantitatively measure the amount of condensation in areas where water droplet paths are formed between electrodes.

[0008] Based on the above, conventional methods using condensation sensors cannot adequately detect the amount of condensation during the most crucial stages: heating and the initial drying phase. Furthermore, condensation sensors degrade quickly with repeated use in high-temperature, high-humidity environments, making it difficult to even verify reproducibility. Therefore, detecting condensation using condensation sensors is unsuitable for this test, where reproducibility is critical.

[0009] The present invention aims to provide a condensation test method for electronic components that can reproduce condensation loads under various test environments of the customer. [Means for solving the problem]

[0010] The condensation test method for electronic components according to the present invention is: A method for testing condensation in electronic components using a test chamber, A base selection process in which a base for the test is selected from among several bases having different heat capacities, The process involves setting the selected test base on a breathable shelf located inside the test chamber, The process of setting electronic components on the aforementioned test base, The process involves covering the test base and the electronic components with a cover member, A step of controlling the temperature inside the test chamber, Includes. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a condensation test method for electronic components that can reproduce condensation loads under various test environments of the customer. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing an overview of the condensation testing apparatus of this embodiment. [Figure 2] This is a perspective view of an electronic component being tested by a condensation testing device. [Figure 3] This is a block diagram showing the control configuration of a condensation testing apparatus. [Figure 4] This is a flowchart showing the flow of the condensation test method. [Figure 5] This graph shows the changes in air temperature inside the test chamber and surface temperature of electronic components during the drying phase of the condensation cycle test process. [Modes for carrying out the invention]

[0013] (Condensation testing device) Using Figure 1, a condensation test apparatus 1 used in the condensation test method for electronic components according to the embodiment of this disclosure will be described. Figure 1 is a schematic diagram showing the outline of a condensation test apparatus for carrying out the condensation test method of this embodiment.

[0014] Condensation test apparatus 1 is a device for performing temperature and humidity cycle tests. Temperature and humidity cycle tests are a test method for determining the suitability of electronic components to be used, transported, or stored under conditions where temperature changes are repeated under high humidity, for example, causing condensation on the surface of electronic components. Specifically, the low temperature / high temperature / high humidity cycle is performed one to multiple times, repeating the formation and drying of condensation.

[0015] The condensation test apparatus 1 has a test apparatus body 2. The test apparatus body 2 has a chamber wall 3, and an internal space 4 is provided within the chamber wall 3. A door 6 with a transparent portion is provided on the front side of the chamber wall 3.

[0016] The internal space 4 is divided by the partition wall 13 into an air-conditioning tank 11 and a test tank 12. The air-conditioning tank 11 is arranged in the rear region of the internal space 4, and the test tank 12 is arranged in the front region of the internal space 4. The partition wall 13 has an opening 13A that communicates between the air-conditioning tank 11 and the test tank 12.

[0017] The air-conditioning tank 11 is a tank for adjusting the temperature of the air sent into the test tank 12 to a predetermined condition. Inside the air-conditioning tank 11, a cooler 31, a heater 32, and a blower 33 are provided. The cooler 31 and the heater 32 adjust the temperature of the air in the air-conditioning tank 11 to a predetermined condition. The blower 33 supplies the air adjusted to a predetermined temperature and humidity into the test tank 12 through the opening 13A. The air supplied into this test tank 12 is returned to the air-conditioning tank 11 through the opening 13A. Incidentally, the humidity of the air in the air-conditioning tank 11 is set in advance to a certain high humidity.

[0018] The test tank 12 is a tank for conducting a dew condensation test on the electronic component 5 to be tested. The test tank 12 has a sample stage 15 as a heating and cooling unit. The electronic component 5 is arranged on the sample stage 15.

[0019] The sample stage 15 is provided above the shelf portion 16. The shelf portion 16 is a mesh-like member that penetrates vertically and has air permeability.

[0020] The sample stage 15 has a pedestal 17 and a heat transfer sheet 18.

[0021] The base 17 is a resin plate, and different thicknesses result in different heat capacities. The base 17 is made of, for example, acrylic resin. However, the base 17 is not limited to an acrylic resin plate; it can be any material with heat capacity on which the electronic components 5 can be placed directly or indirectly. As will be described later, multiple bases with different heat capacities are prepared. Each base with a different heat capacity can be selectively placed on the shelf 16. The electronic components 5 can then be placed directly or indirectly on each base 17 placed on the shelf 16.

[0022] The heat transfer sheet 18 is placed on the base 17. The heat transfer sheet 18 may be a rubber sheet, such as silicone rubber. The heat transfer sheet 18 may also contain fillers such as boron nitride or aluminum nitride. The heat transfer sheet 18 is placed to improve heat transfer between the sample stage 15 and the electronic component 5. More specifically, the heat transfer between the heat transfer sheet 18 and the substrate 19 on which the electronic component 5 is mounted is increased, thereby improving heat transfer from the base 17 to the electronic component 5. The heat transfer sheet 18 is not essential, and the sample stage 15 may be composed solely of the base 17. In this case, the base 17 is preferably made of a material with a surface that has low contact thermal resistance.

[0023] The condensation test apparatus 1 has a cover member 21. The cover member 21 has a closed top and sides and an open bottom, and covers the base 17, the heat transfer sheet 18, and the electronic component 5 from above. Specifically, the cover member 21 is, for example, transparent and covers the entire circumference of the top and sides of the base 17 and the electronic component 5. Air can flow into the cover member's internal space 14 from below the shelf 16. The top of the cover member 21 is also an inclined section that slopes in one direction. Specifically, the rear part of the cover member's internal space 14 is higher and the front part is lower. The cover member 21 is made of resin and may be composed of, for example, acrylic resin or polycarbonate.

[0024] By providing the cover member 21, the humidity inside the cover member 14 is more likely to rise above the humidity in the test chamber 12 (the part outside the cover member 21). As a result, the amount of condensation on the surface of the electronic component 5 can be increased compared to when the cover member 21 is not provided.

[0025] The base 17 is sized to be enclosed by the lower opening of the cover member 21. Air can move between the lower opening of the cover member 21 and the sample stage 15 through the shelf 16 and between the internal space 14 of the cover member 21 and the space below it (see arrows D1 and D2).

[0026] The electronic component 5 may be a chip-type electronic component. For example, it may be a chip-shaped multilayer ceramic electronic component with a roughly rectangular or cubic shape, as shown in Figure 2. Figure 2 is an external perspective view of the electronic component being tested by a condensation test apparatus.

[0027] In this embodiment, the electronic component 5 is a multilayer ceramic electronic component such as a multilayer ceramic capacitor. As shown in Figure 2, the electronic component 5 has a ceramic body 5A, a first external electrode 5B, and a second external electrode 5C.

[0028] More specifically, the multilayer ceramic electronic component includes a plurality of stacked ceramic layers and a plurality of internal conductor layers, and has a ceramic body 5A as a laminate having a first main surface TS1 and a second main surface TS2 facing the height direction T, a first side surface WS1 and a second side surface WS2 facing the width direction W perpendicular to the height direction T, and a first end surface LS1 and a second end surface LS2 facing the length direction L perpendicular to the height direction T and the width direction W. The multilayer ceramic electronic component of this embodiment has at least two external electrodes: a first external electrode 5B disposed on the first end surface LS1 side of the ceramic body 5A and connected to the internal conductor layer, and a second external electrode 5C disposed on the second end surface LS2 side of the ceramic body 5A and connected to the internal conductor layer.

[0029] If the lengthwise dimension of the multilayer ceramic electronic component, which includes the ceramic body 5A and the first external electrode 5B and the second external electrode 5C, is denoted as dimension L, then dimension L may be between 0.1 mm and 15 mm. Furthermore, if the heightwise dimension of the multilayer ceramic electronic component is denoted as dimension T, then dimension T may be between 0.05 mm and 15 mm. Also, if the widthwise dimension of the multilayer ceramic electronic component is denoted as dimension W, then dimension W may be between 0.1 mm and 15 mm. In other words, the maximum dimension of the electronic component 5 may be 15 mm or less. More preferably, dimension L may be between 0.4 mm and 4 mm, dimension T between 0.2 mm and 3 mm, and dimension W between 0.2 mm and 3 mm. In other words, the maximum dimension of the electronic component 5 may be 4 mm or less. However, the size of the electronic component 5 is not limited to these dimensions.

[0030] The electronic component 5 is placed on the sample stage 15 with the circuit board 19 mounted on it. That is, the electronic component 5, mounted on the circuit board 19, is placed on the heat transfer sheet 18 of the sample stage 15 as a sample. However, the electronic component 5 may also be placed on the heat transfer sheet 18 of the sample stage 15 without the circuit board.

[0031] The electronic component 5 to be tested is not limited to a multilayer ceramic capacitor, but may also be chip-type electronic components such as piezoelectric components, thermistors, inductors, resistors, or other electronic components.

[0032] The substrate 19 has a substrate body and a wiring member to which the first external electrode 5B and the second external electrode 5C of the electronic component 5 are connected by metal solder. The substrate body is made of an insulating material such as glass epoxy resin. The wiring member is made of a metal such as Cu.

[0033] The voltage application unit 50 (see Figure 3) applies a voltage to the electronic component 5 placed on the sample stage 15. Specifically, the voltage application unit 50 is electrically connected to the wiring members of the substrate 19. The voltage application unit 50 then applies a voltage between the wiring members, thereby applying a voltage between the first external electrode 5B and the second external electrode 5C of the electronic component 5.

[0034] A first temperature and humidity sensor 22 is installed at the top of the test chamber 12. The first temperature and humidity sensor 22 is a sensor for measuring the temperature and humidity of the air inside the test chamber 12. In the following description, the temperature obtained by the first temperature and humidity sensor 22 will be defined as the "temperature inside the test chamber".

[0035] A second temperature and humidity sensor 23 is provided in the internal space 14 of the cover member 21. The second temperature and humidity sensor 23 is a sensor for measuring the temperature and humidity of the air in the internal space 14 of the cover member 21. The temperature obtained by the second temperature and humidity sensor 23 may be defined as the "temperature inside the test chamber" and used for the control described later.

[0036] A thermocouple 24 is provided on the upper surface of the substrate 19. The thermocouple 24 is a sensor for measuring the temperature corresponding to the surface temperature of the electronic component 5. In this embodiment, the thermocouple 24 is provided on the substrate 19. This allows for the substantial measurement of the surface temperature of the electronic component 5. The thermocouple 24 may also be directly attached to the surface of the electronic component 5. Alternatively, a substrate with the thermocouple 24 provided may be provided near the substrate 19 on the sample stage 15 to substantially measure the surface temperature of the electronic component 5. Hereafter, when it is explained that the surface temperature of the electronic component is being measured, this also includes cases where the temperature corresponding to the surface temperature of the electronic component 5 is being measured, and the surface temperature of the electronic component 5 is being measured substantially.

[0037] As shown in Figure 3, the condensation test apparatus 1 has a control unit 51. Figure 3 is a block diagram of the control unit of the condensation test apparatus of this embodiment.

[0038] The control unit 51 is configured to include, for example, an arithmetic processor such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array). The various functions of the control unit 51 are realized, for example, by executing a program (application) stored in the storage unit 56. The program (application) may be provided via a network, or it may be provided recorded on a computer-readable storage medium such as a CD-ROM (Compact Disc Read Only Memory) or a DVD (Digital Versatile Disc).

[0039] The memory unit 56 consists of a recording medium such as ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a removable memory card. Examples of recording media include non-transitory tangible media.

[0040] The control unit 51 can receive signals from the input unit 52, the first temperature and humidity sensor 22, the second temperature and humidity sensor 23, and the thermocouple 24. The input unit 52 is composed of a keyboard, touch panel, or the like. The operator uses the input unit 52 to input information such as test conditions. The input unit 52 may also be an input unit that receives information transmitted from a higher-level system or the like.

[0041] The control unit 51 can be controlled by transmitting control signals to the voltage application unit 50, the cooler 31, the heater 32, and the blower 33.

[0042] The control unit 51 includes a test condition setting unit 53, a voltage control unit 54, and an air temperature adjustment unit 55 as functional blocks that realize the above control functions.

[0043] The test condition setting unit 53 sets various test conditions related to the condensation cycle test based on the input information entered into the input unit 52.

[0044] The voltage control unit 54 controls the magnitude of the applied voltage applied to the electronic component 5 based on the conditions set by the test condition setting unit 53. Specifically, the voltage control unit 54 controls the voltage application unit 50 based on the above conditions.

[0045] The air temperature control unit 55 controls the cooler 31, heater 32, and blower 33 in the air condition adjustment tank 11 so that the temperature of the air in the air condition adjustment tank 11 reaches the target temperature.

[0046] As described above, the control unit 51 is composed of multiple functional blocks, but each functional block does not necessarily have to be physically separate, and one CPU may implement the functions of multiple functional blocks. Furthermore, the control unit 51 may be located in two or more separate locations. In addition, all or part of the control unit 51 may be located in a server (not shown).

[0047] The memory unit 56 stores various test conditions set by the test condition setting unit 53. The memory unit 56 may also store programs for executing various functions of the control unit 51.

[0048] (Condensation test method) The condensation test method for electronic component 5 will be explained using Figure 4. Figure 4 is a flowchart showing the flow of the condensation test method. Note that the order of the following steps is not particularly limited. Each step can be omitted or rearranged as needed. Also, multiple steps may be performed simultaneously, or some or all of them may be performed at the same time. The numbers assigned to the steps are used solely for the purpose of explanation.

[0049] (1) Test condition setting process (S1) For example, an operator inputs test conditions into an input unit 52 such as a keyboard or touch panel. The test condition setting unit 53 sets the test conditions based on the input information entered into the input unit 52. The test condition setting unit 53 sets test conditions such as the applied voltage (described later), the target temperature and target humidity of the air in the test chamber 12, the time of the condensation process, the time of the drying process, and the number of cycles for the condensation cycle test.

[0050] (2) Base selection process (S2) From among several bases with different heat capacities, a test base with an appropriate heat capacity is selected to reproduce the conditions of other test equipment. This allows for base selection. As a result, the amount of condensation on the surface of electronic components can be changed to appropriately form water droplet paths between component electrodes, and furthermore, migration can be controlled. In other words, by changing the thickness of the base (i.e., heat capacity), it has become possible to test the migration resistance of electronic components under different set environments.

[0051] For example, the base 17 selected for this test is preferably one in which the difference in migration evaluation results of electronic components with different water bridge resistance characteristics is greater than that of other bases. For example, it is the base in which the difference in migration evaluation results is maximized.

[0052] More specifically, the base selection process includes the base selection pre-test described below, that is, a preliminary test conducted before selecting a base.

[0053] (2-1) A step of preparing a first electronic component and a second electronic component having different water bridge resistance characteristics from the first electronic component.

[0054] (2-2) The process of preparing multiple bases having different heat capacities.

[0055] (2-3) A step of performing condensation tests on the first and second electronic components using multiple bases having different heat capacities.

[0056] (2-4) A step in which the difference in migration evaluation results between the first electronic component and the second electronic component is greater than that of the other bases, and is selected as the base for the main test selected in the base selection step.

[0057] This allows the process of controlling the temperature inside the test chamber 12 using the base selected for the main test during the base selection pre-test.

[0058] As an experimental example, Table 1 below shows the results of migration evaluation when condensation tests were conducted on capacitor A (normal) as the first electronic component and capacitor B (water-repellent) as the second electronic component, with the base thickness varied between 6 and 13 mm. Specifically, Table 1 shows the number of occurrences and condensation amounts of Sn-ECM (Sn electrochemical migration), Ag-ECM (Ag electrochemical migration), and Ni-ECM (Ni electrochemical migration).

[0059] Capacitor A is a sample in which the surface of the laminate has not been treated with a water-repellent coating. In capacitor A, the contact angle with water on the surface of the laminate is generally low, and water droplet paths tend to form between the first and second external electrodes. In other words, capacitor A is a capacitor with poor water bridge resistance (a capacitor in which water bridges are likely to occur).

[0060] Capacitor B is a sample in which the surface of the laminate has been treated with a water-repellent coating. Capacitor B has a high contact angle with water on at least a portion of the surface of the laminate, making it difficult for water droplet paths to form between the first and second external electrodes. In other words, capacitor B is a capacitor with good water bridge resistance (a capacitor in which water bridges are less likely to occur).

[0061] As described above, capacitors with poor water bridge resistance are prone to water droplet paths forming between the external electrodes. When water droplet paths form between the external electrodes, electrochemical migration due to the metal components constituting the external electrodes is more likely to occur.

[0062] For example, capacitors as electronic components sometimes use Sn plating on their external electrodes, in which case Sn-ECM (Sn-Electrode Coating) may be considered as migration. For example, capacitors sometimes use a conductive resin layer containing Ag (silver) filler on their external electrodes, in which case Ag-ECM (silver-electrode coating) may be considered as migration. For example, capacitors sometimes use Ni (ni-coating) on ​​their external electrodes, in which case Ni-ECM (ni-coating) may be considered as migration.

[0063] [Table 1]

[0064] (2-A) For example, if a customer reports that "Ag-ECM occurred in capacitor A, but not in capacitor B," a condensation test is conducted, and evaluation results like those shown in Table 1 are obtained.

[0065] Bases 6mm and 7mm thick: In capacitor A, migration of Sn and Ni occurred, but migration of Ag did not. In capacitor B, migration of Sn, Ni, and Ag did not occur. In this case, since Ag-ECM did not occur in capacitor A, the amount of condensation was insufficient, and the migration evaluation results in the customer's test environment, which is another test environment, could not be reproduced.

[0066] Bases with thicknesses of 8mm and 9mm: In capacitor A, migration of Sn, Ni, and Ag has occurred. In capacitor B, migration of Sn, Ni, and Ag has not occurred. In this case, Ag-ECM has occurred in capacitor A, but not in capacitor B, indicating that the amount of condensation is appropriate and that the migration evaluation results in the customer's test environment have been reproduced.

[0067] Bases with thicknesses of 10mm and 13mm: In capacitor A, migration occurs with Sn, Ni, and Ag. In capacitor B, migration also occurs with Sn, Ni, and Ag. In this case, Ag-ECM is occurring in capacitor B as well, indicating excessive condensation, and the migration evaluation results in the customer's test environment cannot be reproduced.

[0068] From the above evaluation results, it can be seen that the thicker the base (the greater the heat capacity), the slower the surface temperature of the electronic components follows the temperature of the test chamber, resulting in a greater amount of condensation.

[0069] As mentioned above, if a customer reports that "migration occurred in capacitor A, but not in capacitor B," the electronic component manufacturer will know that they can reproduce the customer's test conditions by using a base with a thickness of 8-9 mm.

[0070] (2-B) For example, if a customer reports that "Ag-ECM occurred in capacitor A," a condensation test is conducted, and evaluation results like those shown in Table 1 are obtained.

[0071] Bases with a thickness of 6mm and 7mm: Ag-ECM did not occur even with capacitor A, indicating insufficient condensation, and the migration evaluation results in the customer's test environment, which is a different test environment, could not be reproduced.

[0072] Bases with thicknesses of 8mm, 9mm, 10mm, and 13mm: Ag-ECM is generated in capacitor A, but not in capacitor B. This indicates that the amount of condensation is appropriate and may be able to reproduce the migration evaluation results in the customer's test environment.

[0073] As mentioned above, if a customer reports that "Ag-ECM occurred in capacitor A," the electronic component manufacturer can see that there is a high probability that they can reproduce the customer's test conditions by using a base with a thickness of 8 to 13 mm. Then, based on the migration evaluation results when using bases with a thickness of 8 mm and 9 mm, they can propose to the customer that adopting capacitor B may improve the Ag-ECM.

[0074] (2-C) For example, even if a customer reports that "Sn-ECM occurred in capacitor A, but Ag-ECM did not," a condensation test is conducted, and evaluation results like those shown in Table 1 are obtained.

[0075] Bases with a thickness of 6mm and 7mm: Sn-ECM is occurring in capacitor A, while Ag-ECM is not. This indicates that the amount of condensation is appropriate and that the migration evaluation results in the customer's test environment may be reproducible.

[0076] Bases with thicknesses of 8mm, 9mm, 10mm, and 13mm: Since both Sn-ECM and Ag-ECM are occurring in capacitor A, the amount of condensation is excessive, and the migration evaluation results in the customer's test environment cannot be reproduced.

[0077] As mentioned above, if a customer reports that "Sn-ECM occurred in capacitor A, but Ag-ECM did not," the electronic component manufacturer can see that there is a high probability that they can reproduce the customer's test conditions by using a base with a thickness of 6 to 7 mm.

[0078] As described above, in the base selection process, the base that can reproduce the migration evaluation results in other test environments with higher reproducibility than other bases is selected as the base for the main test. The base selection pretest for selecting the base for the main test may include the steps of preparing electronic components, preparing multiple bases with different heat capacities, conducting condensation tests on the electronic components using each of the multiple bases with different heat capacities, and selecting the base that shows high reproducibility of the migration evaluation results in other test environments as the base for the main test selected in the base selection process.

[0079] Furthermore, in the base selection process, a base in which the difference in migration evaluation results of electronic components with different water bridge resistance characteristics is greater than that of other bases may be selected as the base for the main test. The base selection pretest for selecting the base for the main test may include the steps of preparing a first electronic component and a second electronic component having different water bridge resistance characteristics from the first electronic component; preparing a plurality of bases having different heat capacities; conducting condensation tests on the first and second electronic components using each of the plurality of bases having different heat capacities; and selecting a base in which the difference in migration evaluation results between the first and second electronic components is greater than that of other bases as the base for the main test selected in the base selection process.

[0080] The migration evaluation results may be those of Ag, Sn, Ni, or other metals contained in the electronic component.

[0081] Furthermore, in the base selection process, a base in which the difference in migration evaluation results for different types of metals is greater than that of other bases may be selected as the base for the main test. The base selection pre-test for selecting the base for the main test may include the steps of preparing electronic components, preparing multiple bases with different heat capacities, conducting condensation tests on the electronic components using each of the multiple bases with different heat capacities, and selecting a base in which the difference between the migration evaluation result for a first metal and the migration evaluation result for a second metal different from the first metal is greater than that of other bases, as the base for the main test selected in the base selection process. In this case, the migration evaluation result for the first metal may be the migration evaluation result for any of Sn, Ag, or Ni, and the migration evaluation result for the second metal may be a metal different from the first metal, and may be the migration evaluation result for any of Sn, Ag, or Ni. For example, the migration evaluation result for the first metal may be the migration evaluation result for Sn, and the migration evaluation result for the second metal may be the migration evaluation result for Ag.

[0082] Furthermore, in the base selection process, a base in which the difference in migration evaluation results of electronic components of different sizes is greater than that of other bases may be selected as the base for the main test. The base selection pretest for selecting the base for the main test may include the steps of preparing a first electronic component and a second electronic component of a different size from the first electronic component; preparing a plurality of bases having different heat capacities; conducting condensation tests on the first and second electronic components using each of the plurality of bases having different heat capacities; and selecting a base in which the difference in migration evaluation results between the first and second electronic components is greater than that of other bases as the base for the main test selected in the base selection process.

[0083] (3) Base assembly process (S3) The sample stand 15, including the selected base 17, is placed on the shelf 16 located inside the test chamber 12.

[0084] (4) Electronic component assembly process (S4) The electronic component 5 is placed inside the test chamber 12. Specifically, the electronic component 5 is placed on the sample stage 15 inside the test chamber 12. More specifically, the electronic component 5, mounted on a circuit board 19, is placed on the heat transfer sheet 18 of the sample stage 15. The wiring members of the circuit board 19 are electrically connected to the voltage application unit 50.

[0085] (5) Covering process (S5) The cover member 21 covers the sample stage 15 and the electronic component 5. This increases the amount of condensation in the condensation cycle test described later, ensuring the formation of a water droplet path between the first external electrode 5B and the second external electrode 5C, and further controlling the generation of Ag-ECM.

[0086] (6) Voltage application process (S6) A voltage is applied to the electronic component 5 by the voltage application unit 50. The applied voltage may be, for example, the rated voltage of the electronic component 5. The applied voltage may be, for example, 4V or more and 400V or less. The magnitude of the applied voltage is controlled by the voltage control unit 54 based on the conditions set by the test condition setting unit 53. In principle, the voltage is continuously applied to the electronic component 5 during the condensation cycle test. It is preferable that the voltage application be started before the condensation cycle test process described later. However, the voltage application may be started after the condensation cycle test process has started. Note that the voltage application may be intermittent.

[0087] (7) Steps to control the temperature inside the test chamber 12 (7-1) Air condition adjustment process (S7) In the air condition adjustment process, the temperature and humidity of the air inside the test chamber 12 are stabilized. Specifically, air whose temperature and humidity conditions have been adjusted in the air condition adjustment chamber 11 is supplied into the test chamber 12.

[0088] More specifically, the process of controlling the temperature inside the test chamber 12 includes the following steps.

[0089] (7-2) Condensation cycle test process (S8) After the air temperature and humidity in the test chamber 12 are stabilized through the air condition adjustment process, a condensation cycle test process is carried out in which a condensation process and a drying process are repeatedly performed on the electronic component 5.

[0090] In the condensation cycle test process, the air temperature control unit 55 controls the cooler 31, heater 32, and blower 33 based on a comparison between the set target temperature and the temperature detected by the first temperature and humidity sensor 22, so that the temperature detected by the first temperature and humidity sensor 22 approaches the target temperature.

[0091] As a result, air that has been adjusted to a predetermined temperature and humidity in the air condition adjustment chamber 11 is sent into the test chamber 12 through the opening 13A.

[0092] (7-2-1) Condensation process (heating process) The temperature inside the test chamber 12 is rapidly increased. This causes both the test chamber temperature and the surface temperature of the electronic component 5 to rise. Because the electronic component 5 has a larger heat capacity than air, its temperature rises more slowly than the surroundings, resulting in a temperature difference compared to the test chamber temperature. As a result, condensation forms on the surface of the electronic component 5.

[0093] (7-2-2) Drying process (temperature lowering process) The temperature inside the test chamber 12 is rapidly lowered. This dries and removes any condensation adhering to the surface of the electronic component 5. At this time, it is preferable to circulate the air inside the test chamber to lower the humidity.

[0094] For example, the temperature of the air in the space 14 inside the cover member rises from 20°C to 80°C during the heating phase and falls from 75°C to 20°C during the drying phase.

[0095] For example, the humidity of the air in the space 14 inside the cover member is 98-100% RH during the heating phase and 45-55% RH during the drying phase.

[0096] (8) Final measurement (S9) As a final measurement, migration evaluation of electronic components is performed. Specifically, electrical measurements and mechanical inspections are used for migration evaluation. For example, the presence or absence of Ag-ECM in electronic components is investigated using an optical microscope, scanning electron microscope, or energy-dispersive X-ray spectrometer.

[0097] In this final measurement, it may be determined whether the amount of condensation was appropriate or not. Figure 5 will be used to explain how to determine whether the amount of condensation was appropriate or not. Figure 5 is a graph showing the changes in the air temperature inside the test chamber and the surface temperature of the electronic components during the drying phase of the condensation cycle test process.

[0098] In Figure 5, the vertical axis represents the test chamber temperature A1 and the surface temperature B1 (°C) of the electronic component, and the horizontal axis represents the elapsed time (minutes) since the start of the test.

[0099] As shown in Figure 5, during the drying phase, in the initial stage (first phase), the surface temperature B1 is lower than the test chamber temperature A1. Then, in the next stage (second phase), the surface temperature B1 of the electronic component becomes higher than the test chamber temperature A1. The time C1 that has elapsed from the start of the test until the above timing (i.e., when the first and second phases switch) is defined as the "drying time". It is presumed that condensation has disappeared during this drying time, and therefore the maximum amount of condensation during the test can be obtained from the drying time. In other words, the maximum amount of condensation can be estimated from the temperature behavior during the drying phase.

[0100] By checking this drying time, it is possible to confirm whether condensation was stable in each test run. In other words, it is possible to determine whether the amount of condensation was appropriate in the evaluation of migration. If the amount of condensation is appropriate, it is guaranteed that the evaluation of migration is appropriate. If the amount of condensation is not appropriate, the test results will be judged as inappropriate.

[0101] If the amount of condensation is inappropriate, various conditions may be changed in subsequent tests to make the amount of condensation appropriate. For example, if the amount of condensation is excessive, the amount of condensation can be reduced to an appropriate level by reducing the thickness of the base (reducing the heat capacity).

[0102] With the above configuration and method, it is possible to provide a condensation test method for electronic components that can reliably detect the occurrence of migration such as Ag-ECM and can reproduce condensation loads under various test environments of the customer.

[0103] Furthermore, the process may include a step to obtain condensation test results using a selected test base in combination with multiple types of electronic components. The condensation test results may be, for example, migration evaluation results. The multiple types of electronic components may be, for example, electronic components with different water bridge resistance characteristics. The multiple types of electronic components may also be, for example, electronic components of different sizes. This makes it possible to reproduce and estimate the condensation test results of various electronic components under various test environments of the customer, and to propose appropriate electronic components to the customer.

[0104] <1> A method for testing condensation in electronic components using a test chamber, A base selection process in which a base for the test is selected from among several bases having different heat capacities, The process involves setting the selected test base on a breathable shelf located inside the test chamber, The process of setting electronic components on the aforementioned test base, The process involves covering the test base and the electronic components with a cover member, A step of controlling the temperature inside the test chamber, A method for testing condensation in electronic components, including [specific component name].

[0105] <2> The test base selected in the base selection process is a base that shows a greater difference in migration evaluation results for electronic components with different water bridge resistance characteristics compared to other bases. The aforementioned test base is selected through a base selection pre-test. <1> Condensation testing method for the electronic components described.

[0106] <3> The aforementioned base selection pre-test is, A step of preparing a first electronic component and a second electronic component having different water bridge resistance characteristics from the first electronic component, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the first electronic component and the second electronic component using each of several bases having different heat capacities, The process includes selecting a base in which the difference in migration evaluation results between the first electronic component and the second electronic component is greater than that of other bases, as the base for the main test selected in the base selection process. <2> The condensation test method for electronic components described below.

[0107] <4> The migration evaluation results mentioned above are the results of the migration evaluation for Ag. <2> or <3> The condensation test method for electronic components described below.

[0108] <5> The migration evaluation results mentioned above are the results of the migration evaluation of Sn. <2> or <3> The condensation test method for electronic components described below.

[0109] <6> The migration evaluation results mentioned above are the results of the migration evaluation of Ni. <2> or <3> The condensation test method for electronic components described below.

[0110] <7> The base selected in the base selection step is a base in which the difference in migration evaluation results for different types of metals is greater than that of other bases. The aforementioned test base is selected through a base selection pre-test. <1> The condensation test method for electronic components described below.

[0111] <8> The aforementioned base selection pre-test is, The process of preparing electronic components, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the electronic component using multiple bases having different heat capacities, The process includes selecting a base as the base for the main test selected in the base selection process, in which the difference between the migration evaluation result of the first metal and the migration evaluation result of a second metal different from the first metal is greater than that of other bases. <7> The condensation test method for electronic components described below.

[0112] <9> The migration evaluation result for the first metal may be the migration evaluation result for any of Sn, Ag, or Ni, and the migration evaluation result for the second metal may be the migration evaluation result for a metal different from the first metal, and is the migration evaluation result for any of Sn, Ag, or Ni. <8> The condensation test method for electronic components described below.

[0113] <10> The test base selected in the base selection process is a base that can reproduce migration evaluation results in other test environments with higher reproducibility than other bases. The aforementioned test base is selected through a base selection pre-test. <1> The condensation test method for electronic components described below.

[0114] <11> The aforementioned base selection pre-test is, The process of preparing electronic components, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the electronic component using multiple bases having different heat capacities, The process includes selecting a base that exhibits high reproducibility of migration evaluation results in other test environments as the base for the main test selected in the base selection process, <10> The condensation test method for electronic components described below.

[0115] <12> The step of controlling the temperature inside the test chamber is: A condensation step is performed by raising the temperature inside the test chamber to cause condensation on the electronic components, The process includes a drying step in which the condensation is dried by lowering the temperature inside the test chamber after the condensation step, <1> ~ <11> A condensation test method for electronic components as described in any of the following.

[0116] <13> In the drying process, in the first phase, the temperature inside the test chamber is lower than the temperature corresponding to the surface temperature of the electronic component, and in the second phase following the first phase, the temperature corresponding to the surface temperature of the electronic component is higher than the temperature inside the test chamber. The time until the transition between the first phase and the second phase is determined to be the drying time. <12> The condensation test method for electronic components described below.

[0117] <14> The process further includes determining the amount of condensation on the electronic component using the aforementioned drying time. <13> The condensation test method for electronic components described below.

[0118] (modified version) Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described herein can be arbitrarily combined as needed.

[0119] With regard to the structure of the test chamber and the air conditioning chamber, their relative positions, the type of cooling means provided on the sample stage, and the specific configuration of the air conditioning chamber, various applications and modifications can be made within the scope of the invention.

[0120] A humidifier may be provided to adjust the humidity inside the condensation test apparatus. A hot water bath may be used as the humidifier. A hot water bath may be placed at the bottom of the test chamber, and the humidity may be adjusted by controlling the temperature of this bath during the condensation process. In this case, the steam from the hot water bath can effectively increase the humidity inside the cover. [Explanation of Symbols]

[0121] 1: Condensation testing apparatus 5: Electronic components 11: Air Condition Adjustment Tank 12: Test chamber 15: Sample stage 16:Shelf 17: Pedestal 18: Heat transfer sheet 19: Circuit board 21: Cover component 22: First temperature and humidity sensor 23: Second temperature and humidity sensor 24: Thermocouple 31:Cooler 32: Heater 33: Blower 50: Voltage application section 51: Control Unit

Claims

1. A method for testing condensation in electronic components using a test chamber, A base selection process in which a base for the test is selected from among several bases having different heat capacities, The process involves setting the selected test base on a breathable shelf located inside the test chamber, The process of setting electronic components on the aforementioned test base, The process involves covering the test base and the electronic components with a cover member, A step of controlling the temperature inside the test chamber, A method for testing condensation in electronic components, including [specific component name].

2. The test base selected in the base selection process is a base that shows a greater difference in migration evaluation results for electronic components with different water bridge resistance characteristics compared to other bases. The condensation test method for electronic components according to claim 1, wherein the test base is selected by a pre-test for base selection.

3. The aforementioned base selection pre-test is, A step of preparing a first electronic component and a second electronic component having different water bridge resistance characteristics from the first electronic component, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the first electronic component and the second electronic component using each of several bases having different heat capacities, A method for testing condensation of an electronic component according to claim 2, comprising the step of selecting a base in which the difference in migration evaluation results between the first electronic component and the second electronic component is greater than that of other bases, as the base for the main test selected in the base selection step.

4. The condensation test method for electronic components according to claim 2 or claim 3, wherein the migration evaluation result is the result of the migration evaluation of Ag.

5. The condensation test method for electronic components according to claim 2 or claim 3, wherein the migration evaluation result is the result of the migration evaluation of Sn.

6. The condensation test method for electronic components according to claim 2 or claim 3, wherein the migration evaluation result is the result of the migration evaluation of Ni.

7. The base selected in the base selection step is a base in which the difference in migration evaluation results for different types of metals is greater than that of other bases. The condensation test method for electronic components according to claim 1, wherein the test base is selected by a pre-test for base selection.

8. The aforementioned base selection pre-test is, The process of preparing electronic components, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the electronic component using multiple bases having different heat capacities, A method for testing condensation in an electronic component according to claim 7, comprising the step of selecting a base as the base for the main test selected in the base selection step, wherein the difference between the migration evaluation result of a first metal and the migration evaluation result of a second metal different from the first metal is greater than that of other bases.

9. The condensation test method for electronic components according to claim 8, wherein the migration evaluation result of the first metal may be the migration evaluation result of any of Sn, Ag, or Ni, and the migration evaluation result of the second metal is the migration evaluation result of a metal different from the first metal, and is the migration evaluation result of any of Sn, Ag, or Ni.

10. The test base selected in the base selection process is a base that can reproduce migration evaluation results in other test environments with higher reproducibility than other bases. The condensation test method for electronic components according to claim 1, wherein the test base is selected by a pre-test for base selection.

11. The aforementioned base selection pre-test is, The process of preparing electronic components, The process of preparing multiple bases with different heat capacities, A step of performing a condensation test on the electronic component using multiple bases having different heat capacities, A method for testing condensation of an electronic component according to claim 10, comprising the step of selecting a base that shows high reproducibility of migration evaluation results in other test environments as the base for the main test selected in the base selection step.

12. The step of controlling the temperature inside the test chamber is: A condensation step is performed by raising the temperature inside the test chamber to cause condensation on the electronic components, A method for testing condensation of an electronic component according to any one of claims 1 to 3, 7 to 11, comprising a drying step of drying the condensation by lowering the temperature inside the test chamber after the condensation step.

13. In the drying process, in the first phase, the temperature inside the test chamber is lower than the temperature corresponding to the surface temperature of the electronic component, and in the second phase following the first phase, the temperature corresponding to the surface temperature of the electronic component is higher than the temperature inside the test chamber. The method for testing condensation of an electronic component according to claim 12, wherein the time until the first phase and the second phase switch is determined to be the drying time.

14. The method for testing condensation on an electronic component according to claim 13, further comprising the step of determining the amount of condensation on the electronic component by using the drying time.

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