Electronic component reliability verification method, electronic component reuse system, and electronic component

Abstract

To provide an electronic component, an electronic component reliability verification method, and an electronic component reuse system that enable a method of manufacturing an electronic component that can be reused for industrial purposes.SOLUTION: In a reliability verification method of removing an electronic component from a first control board after market operation by using the electronic components attached to a first control board, attaching the electronic component to a second control board and reusing it, and performing guarantee of the performance at least until reuse before attaching the electronic components to the first control board, for the electronic component mounted on the control board, the load of the reused electronic component is defined, the load of the reused electronic component is quantified, and test to confirm that the performance is equivalent to that of the initial electronic component immediately after production is conducted.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the reuse of electronic components, and more particularly to an electronic component reliability verification method, an electronic component reuse system, and an electronic component that are suitable for reuse. [Background technology]

[0002] When electronic components are manufactured and shipped, their reliability is evaluated according to the standard number of years of use that corresponds to the life cycle of the product in which the electronic components are used.

[0003] For example, the reliability of solder joints of electronic components soldered to printed circuit boards is evaluated by selecting accelerated tests specified by standards such as JEDEC (Joint Electron Device Engineering Councils), JIS (Japanese Industrial Standards), and MIL (United States Military Standards), which simulate the actual operating environment of the board.

[0004] Regarding the reliability evaluation of such electronic components, Patent Document 1 discloses "a combined environmental testing method for performing a reliability evaluation of cracks in solder joints of an electronic component mounting board, the combined environmental testing method comprising the steps of: conducting a temperature cycle test on the electronic component mounting board until an initial crack appears in the solder joint; and conducting a vibration test on the electronic component mounting board that has been subjected to the temperature cycle test." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-300142 Summary of the Invention [Problem to be solved by the invention]

[0006] Electronic components are installed and used in many devices, but elevators, for example, operate alongside buildings for nearly several decades, so they are subject to regular repairs and maintenance. During these repairs, the circuit boards that control the elevator are also updated, and the electronic components mounted on the boards are replaced. Because elevator maintenance takes a fairly long time, electronic components are stockpiled for long periods of time to prepare for the risk that production of the components will be discontinued and replacements will not be available in the future.

[0007] An example of such electronic components that require long-term stockpiling is the surface-mount IC (QFP (Quad Flat Package)) components used in microcomputers. Furthermore, when stockpiles run out, it will be necessary to reuse electronic components from recovered circuit boards.

[0008] In order to mount the removed components onto new boards, it was necessary to confirm the reliability of the components, including the removal process and operation after the reused components were mounted.However, the reliability evaluation standards, which consist of accelerated tests determined by JEDEC standards, JIS standards, MIL standards, etc., are standards for using electronic components only once and do not cover the reuse process.

[0009] In view of the above, an object of the present invention is to provide an electronic component reliability verification method, an electronic component reuse system, and an electronic component that make it possible to realize a manufacturing method for electronic components that can be reused for industrial applications. [Means for solving the problem]

[0010] In view of the above, the present invention provides a reliability verification method for assuring performance at least during the period up to reuse, in which an electronic component is attached to a first control board and used, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse, in a stage prior to attaching the electronic component to the first control board, the method defining the load of the reused electronic component with respect to the electronic component mounted on the control board, quantifying the load of the reused electronic component, and carrying out a test to confirm that the performance is equivalent to that of the initial electronic component immediately after production. The test includes multiple heating for solder joints and two types of tests for moisture absorption and thermal expansion / contraction during the first and second field operation periods. A reliability verification method characterized by 。 " Furthermore, the present invention provides an electronic component reliability verification method for assuring performance at least during the period up to the reuse of an electronic component, in which an electronic component is attached to a first control board for use, and after market operation, the electronic component is removed from the first control board and attached to a second control board for reuse, prior to the attachment of the electronic component to the first control board, the method comprising the steps of: defining a load on the electronic component to be reused with respect to the electronic component mounted on the control board; quantifying the load on the electronic component to be reused; conducting a test to confirm that the performance is equivalent to that of the electronic component in an initial product immediately after production; measuring the wire bond strength inside the electronic component; and determining a grade based on the degree of strength deterioration.

[0011] Furthermore, in the present invention, "an electronic component is attached to a first control board for use, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse, and a reliability verification method is carried out in a stage prior to the attachment of the electronic component to the first control board to guarantee performance at least until reuse." An electronic component reuse system for electronic components mounted on a control board, the system defines the load of the electronic components to be reused, quantifies the load of the electronic components to be reused, and performs tests to confirm that the performance is equivalent to that of the electronic components in the initial product immediately after production, the tests including multiple heating for soldering and two types of tests for moisture absorption and thermal expansion / contraction during the first and second market operating periods. "An electronic parts reuse system characterized by..." Furthermore, the present invention provides an electronic component reuse system in which "electronic components are attached to a first control board for use, and after operation in the market, the electronic components are removed from the first control board and attached to a second control board for reuse, and, prior to attaching the electronic components to the first control board, an electronic component reliability verification method is executed to guarantee performance at least during the period up to the reuse, wherein, for the electronic components mounted on the control board, a load of the electronic components to be reused is defined, the load of the electronic components to be reused is quantified, and tests are executed to confirm that the performance is equivalent to that of the initial electronic components immediately after production, and the wire bond strength inside the electronic components is measured and a grade is determined based on the degree of strength deterioration." [Effects of the Invention]

[0013] The present invention can provide an electronic component reliability verification method, an electronic component reuse system, and an electronic component that can realize a manufacturing method for electronic components that can be reused for industrial applications. [Brief explanation of the drawings]

[0014] [Figure 1] A conceptual diagram showing the timeline of various processes after the manufacture of electronic components. [Figure 2] FIG. 10 is a diagram showing an example of the contents of electronic component reliability verification executed in a verification stage TOA after electronic component manufacture. [Figure 3] Schematic cross-sectional view of electrodes where a QFP component is mounted on a printed circuit board. [Figure 4] Schematic cross-sectional view of the electrodes after the QFP component has been removed from the printed circuit board. [Figure 5] The figure shows the measurement of the solder height of the electrodes after removing the QFP component from the printed circuit board. [Figure 6] Temperature profile when removing a QFP component from a printed circuit board [Figure 7] FIG. 10 is a diagram showing an example in which it is possible to directly determine from electronic components whether a product has been verified for reuse. [Figure 8] FIG. 10 is a diagram showing an example in which it is possible to indirectly determine from electronic components whether a product has been verified for reuse. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, examples of the present invention will be described. In Example 1, an electronic component reuse system will be described, in Example 2, an electronic component reliability verification method will be described, and in Example 3, an electronic component whose reuse has been verified will be described. [Example]

[0016] In Example 1, an electronic component reuse system will be described. Fig. 1 shows a timeline of various processes after electronic component manufacturing. The upper part of Fig. 1 shows an electronic component reuse system, which is a timeline of various processes according to the present invention, and the lower part of Fig. 1 shows an electronic component reuse system, which is a timeline of various processes currently performed without reuse.

[0017] According to the lower part of this diagram, in the current process, the use of semiconductor electronic components (hereinafter simply referred to as electronic components) 9 begins in process T1 after the manufacturing and verification process T0, and in process T3 the electronic components 9 are incorporated into control boards 4 (printed circuit boards) and shipped.In the subsequent operation process T10, the electronic components are typically operated in the market for about 5 to 7 years, after which they are disposed of due to the end of their product life, etc.

[0018] In contrast to this, in the electronic component reuse system of the present invention shown in the upper part of Fig. 1, the electronic component reliability verification method shown in the second embodiment of the present invention is applied in the manufacturing and verification process T0A of the semiconductor electronic component 9. In the electronic component reliability verification method of the second embodiment, verification is carried out in advance to ensure that the component can withstand use including reuse for, for example, 40 years.

[0019] The verification here involves verifying the reliability of electronic components 9 required for long-term use, such as 40 years, after manufacture. Electronic component 9 here has terminals soldered to a substrate, and the electrode-side joints of the semiconductor chip are connected to electrodes connected to the component's external wiring with metal wires. For such electronic components, the wire strength can be measured by pulling the middle of the wire and accurately measuring its strength. Tests are also conducted early on to simulate the heating that occurs when the component is initially mounted on a substrate, its first operation in the market, the heating that occurs when the component is removed from a substrate after being collected from the market, the mounting heating that occurs when the component is reused, and its second operation in the market.

[0020] In the electronic component reuse system of Figure 1, the flow up to the subsequent operation process T10 is the same as the current process, but after, for example, 20 years of market operation process T10 (the service life of the electronic components), the control board 4 will reach the maintenance period T2. At this time, the control board 4 that has been in operation in the market is collected, and the electronic components 9 that are working properly are removed from that control board 4 and mounted on a new control board 4, a process known as reuse.

[0021] In the reuse and recycling process T5 after this maintenance T2, the electronic components 9 are removed from the control board 4 (process T6), the solder is removed or replenished (process T7), and the electronic components are reassembled and shipped (process T8) to be recycled into reusable electronic components 9, which will be put back into market operation for the next 20 years. If the first 20-year operating period is called the primary usage period T10, then the operating period after reuse and recycling can be called the secondary usage period T20 (reuse period).

[0022] As described above, the electronic component reuse system of the present invention executes verification tests in the verification stage TOA after the manufacture of electronic components, taking into consideration the stresses that the electronic components will be subjected to not only during the primary use period T10 but also during the reuse and recycling process T5 and the secondary use period T20 (reuse period). This makes it possible to reuse electronic components without conducting any special verification when moving to reuse. [Example]

[0023] In the second embodiment, a method for verifying reliability of an electronic component in a verification stage TOA after the electronic component is manufactured will be described.

[0024] Generally, electronic components 9 used for a long period of time deteriorate over time, but in the present invention, this load is quantified in the verification stage TOA after the electronic components are manufactured, and the initial lifespan of the electronic components 9 is estimated in relation to the usage environment, thereby ensuring the reliability of electronic components 9 that can be reused for industrial purposes so that the component performance can be maintained after reuse.

[0025] Figure 2 shows an example of the contents of electronic component reliability verification performed in the verification stage TOA after electronic component manufacturing. This example focuses on the process D11 of the electronic component 9 to be reused, the failure mode D12 to be confirmed, and the test method D13.

[0026] First, looking at process D11 for the electronic component 9 to be reused, this electronic component 9 is attached to the control board 4, then removed for reuse, and heated a total of five times before being reattached. For this reason, the failure mode D12 to be checked in this regard focuses on heat resistance, and the test method D13 involves performing heat treatment test A in advance.

[0027] Furthermore, when considering process D11 for reused electronic components 9 from the perspective of long-term operation spanning 40 years, failure modes D12 to be checked in this regard focus on destruction and moisture resistance, and test method D13 involves conducting high-temperature, high-humidity, and pressure test B in advance. Also, from this perspective, failure modes D12 to be checked in this regard focus on destruction due to expansion and contraction, and test method D13 involves conducting temperature cycle test C in advance.

[0028] The reliability verification of electronic components performed in the verification stage TOA after electronic component manufacture is, for example, as described above. However, since verification of the load during the primary use period T10 of a 40-year usage period has already been performed and is known, it is only necessary to clarify the load during the reuse and regeneration process T5, which is still unknown. The load during the secondary use period T20 (reuse period) can be considered to be equivalent to that during the primary use period T10. For this reason, the following elucidation process will verify the performance of new electronic components and removed electronic components.

[0029] Here, tests are conducted on surface-mounted ICs (QFP components) as electronic components 9, and the results are evaluated. The surface-mounted electronic components 9 used here are a QFP product 9a with 100 pins and a 0.65 mm pitch and a 240 pin QFP product 9b with 0.5 mm pitch, and a BGA product 9c with 479 pins and a 1.27 mm pitch.

[0030] Figure 3 is a cross-sectional view of an electrode where a QFP component is mounted on a printed circuit board, and Figure 4 is a cross-sectional view of the electrode after the QFP component has been removed from the printed circuit board. In these figures, 11 indicates the electrode, 12 indicates the heel, 13 indicates the toe, 17 indicates excess solder, and 18 indicates the solder height. In this example, in the configuration of Figure 3, electronic components 9 (9a, 9b, 9c) are to be removed from control board 4 and reworked to return them to the state of Figure 4 for reuse.

[0031] For these electronic components 9a, 9b, and 9c, verification of the loads imposed on them up to the primary use period T10 has been carried out in the past and is known numerically, so here we verified the load when they are removed from the control board 4. For this rework, parts taken from recovered control boards were used, and unused new parts that had been stored were used for IC life verification. In addition, the reuse process was formulated and whether the IC life was sufficient for reuse operation was verified using the following methods.

[0032] First, we will explain the rework process for the QFP and BGA of the main ICs from the recovered control boards. The common process is to first bake the recovered board to dry out any moisture it has absorbed in the field, then heat and adsorb the desired components to remove them. After that, the solder remaining on the electrodes of the removed components is removed and the electrodes are regenerated using the appropriate method.

[0033] The rework process is outlined below. First, the recovered substrates were baked at 125°C for 24 hours. The moisture absorption test conditions were MSL level 1 (85 / 85%, 196 hours). After leaving the substrates in this atmosphere, the components were immediately removed and heated.

[0034] QFP and BGA component removal was performed using a rework device, with the bottom of the board heated to 100°C and N2 sprayed onto the top heater profile. The component removal was performed in a nitrogen concentration of 99.99%. With other common removal devices, the atmosphere around the components is equivalent to air, even when N2 is sprayed onto them.

[0035] To measure the height of the solder remaining on the backside of the electrode after removing the component, the surface of the surface plate was used as the reference plane, and the distance A to the terminal and the height B of the excess solder were measured with a digital microscope. The height of the excess solder was defined as the value AB.

[0036] Figure 5 shows the measurement of the solder height of the electrodes after the QFP component was removed from the printed circuit board. For example, as shown by the solder height for each pin number on the horizontal axis, it was confirmed that the solder height was approximately 20 μm or less.

[0037] The method for regenerating and reballing BGA electrodes is as follows. After removing the BGA, the flux residue is wiped off with cotton or a cotton swab soaked in cleaning solution. After cleaning, flux is applied. As with the QFP, the solder wick / soldering iron (350°C for Sn3Ag0.5Cu) is used to melt and remove any variations in solder height. The flux residue is then removed with cotton or similar soaked in cleaning solution.

[0038] The reliability test method equivalent to operational degradation is as follows. The destructive test conditions for the PCT test, which simulates the period of operation after QFP and BGA components are first mounted on circuit board 4, are 121°C, 100% RH, 2 atmospheres, and 192 hours. The reliability test conditions after the same components are reworked and remounted on the board as reused components for the second time are 400 cycles: -20°C for 30 minutes, room temperature for 15 minutes, 80°C for 30 minutes, and room temperature for 15 minutes. This is equivalent to 5 years of operation.

[0039] The QFP resin was opened and the Au wire pull test was carried out as follows. The molding resin was removed using a small amount of fuming nitric acid or chemicals. Inside the opened packing, the tensile strength of the Au wire connecting the chip electrode and the lead frame electrode was measured.

[0040] The QFP rework process is as follows. Figure 6 shows the temperature profile when a QFP component is removed from a printed circuit board, along with the measurement locations and measurement result profiles for the board temperature on the component (right side of Figure 6) and near the solder (left side of Figure 6) during QFP rework. The set temperature Tmax was 240°C, and the solder joint and component surface were within 10°C. The QFP rework temperature profile was optimized. As a result, the height of the excess solder on the removed QFP electrodes was 60 μm for a 100-pin QFP and 5 μm for a 240-pin QFP. These were confirmed to be at levels that did not require removal.

[0041] The QFP resin opening and Au wire pull test methods are as follows. The molding resin was opened by removing it with a small amount of fuming nitric acid or other chemicals. The QFP resin opening and Au wire pull test results, in which the tensile strength of the Au wire connecting the chip electrode and lead frame electrode inside the opened packing, were measured, are as follows. The resin was opened from the QFP with the recovered board removed and from the QFP after the heating test (heating at 235°C five times), PCT destruction test (192 hours), and reliability test (400 cycles).

[0042] The initial product's unpacking condition is as shown in Figures 3 and 4, and inspection of the IC surface revealed no corrosion or damage. Measurements of the Au wire tensile strength showed that for the initial product, the product undergoing a series of reliability tests, and the recalled product after 15 years of actual operation, the Au wire tensile strengths of the QFP100-pin packing for the 100-pin QFP and 240-pin QFP were 9.6 gf, 9.72 gf, and 9.96 gf, respectively, with no difference observed after testing. This indicates that the QFP100-pin packing has not deteriorated in the field.

[0043] On the other hand, the average tensile strength of the Au wire in the QFP240 pin packing was 5.6 gf initially, but after the test it was 2.1 gf, and for the market-recalled products it was 2.4 gf. These strengths are equivalent to the MIL standard for φ25 μm Au wire, so there is no problem with the results.

[0044] For tests simulating market operation, salt damage tests can be conducted, for example, assuming operation near the sea. In this case, it is recommended to conduct a 28-day test, which is conducted under conditions conforming to the JIS salt spray test standard JIS 60068-2-52: salt spray using a 5 wt% sodium chloride solution at 15-35°C, followed by exposure to humidity at 40°C and 93% RH for one cycle (7 days), and exposure to standard air once, repeated five times. It is also possible to conduct an appropriate gas corrosion test for tests simulating market operation.

[0045] Based on the results of the above considerations regarding rework, the details of the electronic component reliability verification to be performed in the verification stage TOA after electronic component manufacturing (e.g., heat treatment test A, high temperature and humidity pressure test B, temperature cycle test C) are specifically determined and will be performed before shipment.

[0046] In essence, the reliability verification method described above involves defining the load of reused electronic components mounted on control boards, quantifying the load of the reused electronic components, and confirming that the performance is equivalent to that of the initial electronic components immediately after production. [Example]

[0047] In Example 3, an electronic component verified for reuse will be described. Whether a product is verified for reuse can be determined directly or indirectly from the electronic component.

[0048] For example, a direct means of understanding is to clearly indicate on the surface of electronic component 9 that it is a standard-compliant product, as shown in Figure 7. Standards for reused products are determined in standards such as JEDEC standards, JIS standards, and MIL standards, and products that have passed these standards are marked on the surface of the electronic component with a standard number or the like, making it possible to confirm that the electronic component is reusable. Alternatively, the fact that the component is reusable may be marked directly.

[0049] As an indirect means of understanding, as shown in Figure 8, the model number of the electronic component 9 is engraved on the surface of the electronic component, and by entering the model number into a personal computer (PC), the specifications of the electronic component can be confirmed, thereby confirming that the product is compliant with the standards. [Explanation of symbols]

[0050] T1: Semiconductor electronic component start-up process T2: Control board recovery process during maintenance T3: Assembly and shipping process 4: Control board T5: Reuse and regeneration process T6: Removal process T7: Solder removal / replenishment process T8: Reassembly and shipping process 9: Electronic Components 11: Electrode 12: Heel 13: Toe section 14: Circuit board 16: Heat removal 17: Excess solder 18: Solder height

Claims

1. The electronic component is attached to a first control board for use, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse; a method for verifying reliability of an electronic component for guaranteeing performance at least during a period until reuse, prior to mounting the electronic component on the first control board, the method comprising: Regarding the electronic components mounted on the control board, a load of the electronic components to be reused is defined, the load of the electronic components to be reused is quantified, and a test is performed to confirm that the performance of the reused electronic components is equivalent to that of the initial electronic components immediately after production; The method for verifying the reliability of electronic components is characterized in that the test includes multiple heating tests for solder joints and two types of tests: moisture absorption tests and thermal expansion / contraction tests during the first and second periods of market operation.

2. An electronic component is attached to a first control board and used, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse, and a method for verifying reliability of an electronic component for guaranteeing performance at least during a period until reuse, prior to mounting the electronic component on the first control board, the method comprising: Regarding the electronic components mounted on the control board, a load of the electronic components to be reused is defined, the load of the electronic components to be reused is quantified, and a test is performed to confirm that the performance of the reused electronic components is equivalent to that of the initial electronic components immediately after production; The method for verifying reliability of electronic components comprises measuring the wire bond strength inside the electronic component and determining a grade based on the degree of deterioration of the strength.

3. The electronic component is attached to a first control board for use, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse; an electronic component reuse system that executes a reliability verification method for guaranteeing performance at least during a period until the electronic component is reused, before the electronic component is attached to the first control board, Regarding the electronic components mounted on the control board, a load of the electronic components to be reused is defined, the load of the electronic components to be reused is quantified, and a test is performed to confirm that the performance of the reused electronic components is equivalent to that of the initial electronic components immediately after production; The electronic component reuse system is characterized in that the tests include multiple heating tests for solder joints and two types of tests: moisture absorption tests and thermal expansion / contraction tests during the first and second periods of market operation.

4. An electronic component is attached to a first control board and used, and after operation in the market, the electronic component is removed from the first control board and attached to a second control board for reuse, and an electronic component reuse system that executes an electronic component reliability verification method for guaranteeing performance at least during a period until the electronic component is reused, before the electronic component is attached to the first control board, Regarding the electronic components mounted on the control board, a load of the electronic components to be reused is defined, the load of the electronic components to be reused is quantified, and a test is performed to confirm that the performance of the reused electronic components is equivalent to that of the initial electronic components immediately after production; An electronic component reuse system characterized in that the strength of wire bonds inside the electronic component is measured and a grade is determined based on the degree of deterioration of the strength.

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