JP2010245348A - Testing device and testing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a testing device which inspects reliability of a light emitting device in a state closer to that in the real usage environment, and surely, rapidly, and easily detect a failure article, and the testing method. <P>SOLUTION: The test device 1 comprises: a first controlling means (a controlling part 40) for controlling a temperature and a humidity of an atmosphere outside an emitting device 70 installed in a constant-temperature constant-humidity bath 10; and a second controlling means (a controlling part 20) for controlling a current value and a time to be passed through the emitting device 70 to make the emitting device 70 exposed to the atmosphere generate heat by applying current intermittently. The temperature and the humidity of the atmosphere outside the emitting device 70 installed in a constant-temperature constant-humidity bath 10 are controlled by using the test device 1, and while the current value and the time to be passed through the emitting device 70 to make the emitting device 70 generate heat by applying current intermittently to implement an accelerated life test of the emitting device 70. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a test apparatus for testing a light emitting device and a test method thereof.

As a method for testing deterioration of a semiconductor element, for example, there is an intermittent energization test in which the semiconductor element is intermittently switched.
In this method, an on period for energizing the transistor and an off period for interrupting energization are provided, and the on period and the off period are repeated. In the on period, the transistor generates heat due to power loss and the temperature rises, and in the off period, a temperature drop occurs due to heat dissipation (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 07-027817

  The present invention provides a test apparatus and a test method for a light emitting device provided with a semiconductor element such as an LED (Light Emitting Diode).

  According to one aspect of the present invention, a test tank capable of accommodating a light emitting device, first control means for controlling the temperature and humidity inside the test tank, and the light emitting device installed in the test tank And a second control means for intermittently energizing by controlling the current energized to the test apparatus.

  Further, according to one aspect of the present invention, a light emitting device is installed inside a test tank, and the light emitting device is energized intermittently while controlling the temperature and humidity inside the test tank. There is provided a test method characterized by examining the presence or absence of deterioration.

  According to the present invention, it becomes easier to detect a malfunction of a light emitting device under an actual use environment.

It is a principal part figure of the test apparatus concerning this Embodiment. It is a flowchart for demonstrating the test method of a light-emitting device. It is a figure explaining the switching operation of a light-emitting device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a main part view of the test apparatus according to the present embodiment. FIG. 1A shows a state in which, in addition to the test apparatus 1, a light emitting device 70 as a subject is attached in the test apparatus 1. Further, FIG. 1B shows a cross-section of the main part of the light emitting device 70. The light emitting device 70 corresponds to, for example, an LED (Light Emitting Diode) package.

  As shown in FIG. 1 (a), the test apparatus 1 includes a constant temperature and humidity chamber (test tank) 10, a terminal board (support) 11 disposed in the constant temperature and humidity tank 10, and a terminal board 11. In the state where the light emitting device 70 is mounted, the controller 20 that can control the lighting of the light emitting device 70, the power source (constant current power source) 30 that supplies power to the light emitting device 70, and the constant temperature and humidity chamber 10 And a controller 40 that adjusts (controls) the temperature or humidity of the atmosphere. The control units 20 and 40 and the power supply 30 are arranged outside the constant temperature and humidity chamber 10.

  The control unit 40 controls the temperature and humidity of the atmosphere (for example, air) in the constant temperature and humidity chamber 10 to be constant within a predetermined time range, or changes the temperature and humidity to different temperatures and humidity within the predetermined time range. Take control. For example, the temperature can be controlled in the range of 60 to 110 ° C., and the humidity can be controlled in the range of 60 to 100% RH (RH: relative humidity). In one embodiment, for example, the atmosphere in the constant temperature and humidity chamber 10 can be set to 85 ° C. and 85% Rh, which are severe environmental conditions in a general in-vehicle environment test. Moreover, in the atmosphere in the constant temperature and humidity chamber 10, it can also set to environmental conditions other than the said range as needed. For example, the ambient temperature can be normal temperature (about 25 ° C.) or −40 ° C. Alternatively, the atmosphere can be adjusted to a humidity outside the above range as necessary.

In the test apparatus 1, at least one light emitting device 70 mounted on the mounting substrate 80 can be disposed on the terminal board 11 via the mounting substrate 80. Here, when the mounting board 80 is placed on the terminal board 11, an electrode terminal (not shown) provided on the terminal board 11 and an electrode terminal (not shown) provided on the mounting board 80 are electrically connected.
Thereby, electric power can be supplied from the power supply 30 to each light emitting device 70, and each light emitting device 70 can emit light. In addition, the control unit 20 interposed between the power supply 30 and the terminal board 11 enables the flashing operation of each light emitting device 70. The blinking operation corresponds to, for example, intermittent energization (described later). The control unit 20 incorporates a semiconductor relay switching element, for example.

  Further, the mounting board 80 is a circuit board in which circuits, electrode terminals, and the like are selectively disposed on the main surface, and the light emitting device 70 can be mounted by, for example, soldering. Such a mounting board 80 is also referred to as a printed board or a wiring board. Further, the terminal board 11 of the test apparatus 1 is processed so that an actual mounting board can be mounted.

  Next, the structure of the light emitting device 70 mounted on the mounting substrate 80 will be described. Note that the light emitting device 70 exemplified below is an example, and may be a light emitting device other than the illustrated configuration. As shown in FIG. 1B, the light emitting device 70 includes a resin stem 70s as a base, two lead frames 70l sealed by the resin stem 70s, and an adhesive 71 on one lead frame 70l. And a light emitting element 70c mounted therethrough. The light emitting element 70 c is, for example, an LED, and a lower electrode thereof is bonded to the lead frame 70 l with an adhesive 71. The adhesive 71 is, for example, a silver (Ag) paste. A metal wire 70w is bonded to the upper electrode of the light emitting element 70c, and an end of the metal wire 70w is bonded to the other lead frame 70l.

Further, in the light emitting device 70, the light emitting element 70c, the metal wire 70w, and the like are sealed with a sealing resin 70r. The material of the sealing resin 70r is, for example, an epoxy resin or a silicone resin. The surface of the sealing resin 70r has a convex shape, for example, in order to improve the light collecting property. Further, the lead frame 701 of the light emitting device 70 is joined to an electrode terminal (not shown) of the mounting substrate 80 by an adhesive 72. The adhesive material 72 is, for example, lead (Pb) free solder.
When light is emitted from the light emitting element 70c of the light emitting device 70, the light is condensed and emitted by the convex sealing resin 70r.

And such a light-emitting device 70 may be used as vehicle-mounted illuminations, such as a rear combination lamp of a motor vehicle, for example. Therefore, the light emitting device 70 may be used under severe conditions of high temperature and high humidity such as a tropical climate region.
Further, since the rear combination lamp is generally covered with a resin cover, when the light emitting device 70 is turned on, the periphery of the light emitting element 70c immediately becomes high temperature. Further, not only in a humid climate, but also in the rain or after a car wash, the external atmosphere may become high humidity. Each time the brake is depressed under such a high temperature and high humidity, the light emitting device 70 blinks, and a large thermal stress continues to be applied to the periphery of the light emitting element 70c due to the thermal history.
Thus, the light emitting device 70 is often used under severe conditions.

Next, a test method for the light emitting device 70 using the test apparatus 1 will be described.
FIG. 2 is a flowchart for explaining a test method of the light emitting device.
FIG. 3 is a diagram for explaining the blinking operation of the light emitting device. A test method for the light emitting device 70 will be described with reference to FIGS. The flow illustrated in FIG. 2 and the temperature change illustrated in FIG. 3 are automatically performed by the control units 20 and 40 described above. Or you may comprise so that various conditions, such as preset temperature and humidity, can be adjusted manually via a well-known user interface.

  First, at least one light emitting device 70 is mounted on the mounting substrate 80, and the light emitting device 70 and the mounting substrate 80 are arranged in the test apparatus 1. That is, the mounting substrate 80 on which the light emitting device 70 is mounted is placed on the terminal board 11, and the light emitting device 70 as the subject is installed in the test apparatus 1 (step S10). The reason why the mounting substrate 80 is installed in the test apparatus 1 together with the light emitting device 70 is to evaluate in a state as close to actual use as possible. That is, when actually used as a rear combination lamp or the like, a plurality of light emitting devices 70 are mounted on a molded body similar to the mounting substrate 80. Note that the light emitting device 70 is mounted on the mounting substrate 80 by, for example, soldering the light emitting device 70 to the mounting substrate 80 using a solder reflow furnace (temperature: 245 ° C.).

Next, the atmospheric temperature and humidity in the constant temperature and humidity chamber 10 are set to predetermined conditions (step S20).
For example, assuming a harsh environment (high temperature and high humidity) when the light emitting device 70 is used as an in-vehicle application, the atmosphere in the constant temperature and humidity chamber 10 is changed to a high temperature and high humidity area, in direct sunlight, in rainy weather, and in the ume. For example, the temperature is set to 85 ° C. and the humidity is set to 85% Rh.

Next, the current value (or voltage value) to be applied to each light emitting device 70 is set (step S30).
For example, the setting condition of the current value (or voltage value) includes (1) a current value (or a current value that does not cause destruction of the chip of the light emitting element 70c due to current application) in an atmosphere having a temperature of 85 ° C. and a humidity of 85% Rh. Voltage value), and (2) when the sealing resin 70r is heated by the heat generation of the light emitting element 70c, the temperature of the sealing resin 70r does not exceed the glass transition temperature Tg of the sealing resin 70r. It is a condition that satisfies both a current value (or voltage value) of about a degree.
This is because if one of (1) and (2) is not satisfied, chip breakage occurs during the test and the life test cannot be performed. For example, the current value is about 120 mA.
Furthermore, if both the above (1) and (2) are satisfied and the current (or high voltage) is as large as possible, a test under more severe conditions can be performed.

When the light emitting device 70 is energized with such a current value, the light emitting element 70c generates heat and the light emitting device 70 is heated. At this time, the ambient temperature of the light emitting element 70c is controlled to a temperature satisfying the above (2), and the test is performed.
For example, when the glass transition temperature Tg of the sealing resin 70r is in the range of 100 ° C. to 150 ° C. and the light emitting element 70c is not destroyed by current, the junction temperature of the light emitting element 70c in this test is 100 ° C. The temperature can be set in a range of ˜150 ° C. and lower than the glass transition temperature Tg. Such control of the current value (or voltage value) is performed by the control unit 20 described above.
The setting of the current value is appropriately changed according to the standard of the light emitting element 70c.

In this test, the reason why such a severe current value (or voltage value) is set is that the temperature of the light emitting device 70 is increased to a level just before the light emitting element 70c or the sealing resin 70r is destroyed, This is to perform the test. That is, this is because the acceleration test is performed with a load as large as possible for the light emitting device 70. Such severe conditions are, for example, acceleration test conditions in a state closer to the actual use state of a rear combination lamp used as a brake light of an automobile.
However, if an excessive surge current is added to the current signal during the blinking operation, the light emitting element 70c is easily destroyed at this point. This is because in this test, a maximum current (or maximum voltage) that does not cause destruction of the light emitting element 70c due to the current is always energized. Therefore, regarding the setting of the current value, in addition to the above (1) and (2), a condition that the maximum value of the surge current is suppressed to at least 10% of the set current value (current value during energization) It is desirable to add.

  Next, the light emitting device 70 is caused to blink. For example, the light emitting element 70c of the light emitting device 70 is energized intermittently so that a predetermined time is in the energized state (step S40a) and the predetermined time is in the disconnected state (step S40b). More specifically, for example, power supply to the light emitting element 70c is controlled so as to repeat an energization (on) state for 5 seconds and a non-connection (off) state for 5 seconds.

Here, the intermittent energization method will be described with reference to FIG. FIG. 3A shows the relationship between the time when the energization of the blinking operation is turned on and the current. In FIG. 3A, the horizontal axis represents time, and the vertical axis represents the current value.
As shown in FIG. 3A, the current value suddenly rises with the start of energization, and the current value suddenly falls with the end of energization.
Further, as shown in FIG. 3A, with respect to the current that is intermittently energized, from the rise time until the current signal increases from 10% to 90% of the maximum value of the current signal, and from 90% of the maximum value of the current signal. The fall time to decrease to 10% is controlled within 100 milliseconds (ms). This is because when the current is normally passed through the light emitting element 70c and the temperature of the light emitting device 70 is changed, the temperature change of the junction portion can be handled within 100 ms. The expansion or contraction caused by such a temperature change causes a steep stress change in the light-emitting device 70, and the effect can be tested.
Moreover, the time of an energized state and a disconnection state can be made into 1 second-10 second (in the example mentioned above, 5 second).

When energization is started (turned on), the junction temperature rises at the same time or slightly delayed. Further, when energization is completed (off), the junction temperature decreases at the same time or slightly delayed.
FIG. 3B shows the time dependence of the junction temperature, and shows how the junction temperature changes when intermittent energization is repeated. Moreover, the enlarged view of a temperature change is shown by the upper right of FIG.3 (b).
As shown in FIG. 3B, before the start of energization (0 seconds), since the light emitting device 70 is exposed to the atmosphere in the constant temperature and humidity chamber 10, the junction temperature is the ambient temperature (this embodiment). In the form, it is 85 ° C.).

When the energization of the light emitting element 70c is started and the energization is repeatedly turned on / off, the average temperature _Tav rises while the junction temperature repeats rising and lowering, and after a certain time A, the average temperature _Tav becomes It becomes a steady state. After the average temperature T _av reaches a steady state, the junction temperature repeatedly rises and falls while maintaining the average temperature T _av in the steady state. That is, when the energized state and the disconnected state time are 5 seconds, the temperature rise in 5 seconds and the temperature drop in 5 seconds are continuously applied to the light emitting element 70c.

  The reason for setting the energized state and disconnected state time within 1 to 10 seconds is as follows.

  The rise in temperature when the light emitting device 70 as the subject is turned on rises in about 1 second from the start of energization, and thereafter the temperature rises gradually. Further, the temperature drop at the time of turning off also falls in about 1 second after the energization is turned off, and thereafter the temperature drop becomes gentle. That is, if each time of the energized state and the disconnected state is 1 second, a sufficient temperature change can be given to the light emitting device 70. Therefore, the shortest time for the energized state and the disconnected state is 1 second.

  In addition, the time during which the brake is actually depressed while the vehicle is being driven and the rear combination lamp (light emitting device 70) is lit is normally within 10 seconds except when the vehicle is stopped such as waiting for a long signal. Accordingly, 10 seconds is the longest time for each of the energized state and the disconnected state.

  For these reasons, each of the energized state and the disconnected state is set to 1 second to 10 seconds. Also, if the cycle is within this range, the number of times of cooling (the number of temperature drops and increases) of the light emitting device 70 increases, and a thermal shock close to actual use is given to the light emitting device 70.

Then, when such intermittent energization has been executed a predetermined number of times or when a predetermined time has elapsed since the start of the test, it is determined whether or not a failure has occurred in the light emitting device 70 (step S50).
Here, the malfunction of the light emitting device 70 is, for example, a phenomenon in which a part of the adhesive 71 that joins the light emitting element 70c and the lead frame 70l is peeled off or the metal wire 70w is cut from the light emitting element 70c. Say. Or degradation of the light emitting element 70c corresponds.

  Then, when the intermittent energization has not reached the predetermined number of times, or when there is no malfunction in the light emitting device 70, the process returns to step S40a and the intermittent energization is repeated. In addition, when intermittent energization has reached a predetermined number of times, or when a failure occurs in the light emitting device 70, the current value (or voltage value) in actual use is energized in the light emitting device 70, At least one or more characteristics of forward voltage, luminance, wavelength, and light distribution at that time are evaluated (step S60). In this test, the number of intermittent energizations and the characteristics of the light emitting device 70 are made to correspond to each other to create a database.

  Next, based on the evaluated characteristics, it is determined whether or not the light emitting device 70 under test is broken (for example, not lit) (step S70). If the destruction is not recognized, it is determined whether or not the number of intermittent energizations is the end number (step S80). Here, if it is not the number of times of completion, the process returns to step S40a, and intermittent energization is repeated. If it is the number of times of termination, the test is terminated (step S90). If the light emitting device 70 is found to be destroyed, it is determined whether or not the destruction is the total number of the light emitting devices 70 (step S100). Here, if the destruction reaches the total number of the light emitting devices 70, the test is terminated (step S110). If the destruction does not reach the total number of light emitting devices 70, only the destroyed light emitting devices 70 are removed (step S120), and the remaining light emitting devices 70 are repeatedly energized again to restart the test. . By such a method, the test of the light emitting device 70 is performed.

  As described above, the test apparatus 1 according to the present embodiment includes the first control unit (control unit 40) that controls the temperature and humidity of the atmosphere outside the light emitting device 70 installed in the constant temperature and humidity chamber 10. In order to generate heat by intermittent energization of the light emitting device 70 exposed to the atmosphere, a second control means (control unit 20) for controlling the current value and time of the current to be supplied to the light emitting device 70 is provided. Yes. Then, in order to cause the light emitting device 70 to generate heat by intermittent energization while controlling the temperature and humidity of the atmosphere of the light emitting device 70 installed in the constant temperature and humidity chamber 10 using the test apparatus 1, the light emitting device 70. The deterioration test of the light emitting device 70 is performed while controlling the current value and time of the current to be supplied to the light source.

In the conventional reliability test, only one of the thermal cycle test and the energization test is performed. That is, it is difficult to perform an acceleration test in a harsh environment of high temperature and high humidity while the light emitting device 70 emits light, and it is difficult to detect defective products of the light emitting device under actual use conditions.
Moreover, in a general thermal shock test, for example, it is often rapidly heated from −40 ° C. to 100 ° C. or rapidly cooled from 100 ° C. to −40 ° C., and thermal stress more than actual use is applied to the light emitting device, The acceleration test under conditions close to actual use was not supported.

However, in the present embodiment, for example, the light emitting device 70 is placed in a harsh environment of high temperature and high humidity of 85 ° C. and 85% Rh, and intermittent energization control (flashing operation) is performed to execute the test. Yes. Thereby, the light-emitting device 70 is tested under conditions close to actual use.
Therefore, if the light emitting device is designed and developed based on the test results using the test apparatus 1, a more reliable light emitting device can be realized.
Further, if the test apparatus 1 is used, it is possible to recognize in advance the test results under conditions close to actual use before mass production of the light emitting device 70, so that it is easy to extract a precise problem during the development stage. Therefore, the development efficiency of the light emitting device 70 can be greatly improved. And the reliability can be improved by mass-producing the light-emitting device 70 which cleared the test result.

The embodiments of the present invention have been described above with reference to specific examples. However, the present embodiment is not limited to these specific examples. In other words, those obtained by appropriately modifying the design of the above specific examples by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate.
In addition, each element included in each of the above-described embodiments can be combined as long as technically possible, and combinations thereof are also included in the scope of the present invention as long as they include the features of the present invention.
In addition, in the category of the idea of the present invention, various changes and modifications that can easily be made by those skilled in the art are also included.

1 Test equipment
10 Constant temperature and humidity chamber
11 Terminal board
20, 40 control unit
30 power supply
70 Light Emitting Device
70c light emitting device
70l lead frame
70r sealing resin
70s resin stem
70w metal wire
71, 72 Adhesive
80 Mounting board

Claims (9)

A test chamber capable of accommodating a light emitting device;
First control means for controlling the temperature and humidity inside the test chamber;
A second control means for controlling the current supplied to the light emitting device installed in the test tank to intermittently supply current;
A test apparatus comprising:   2. The test according to claim 1, wherein the first control unit executes control for maintaining the temperature inside the test tank at 60 to 110 ° C. and maintaining the humidity at 60 to 100% Rh. apparatus.   2. The test apparatus according to claim 1, wherein the second control unit is configured to intermittently energize a current within a range in which a temperature of a sealing resin of the light emitting device does not exceed a glass transition temperature thereof.   The test apparatus according to claim 1, wherein a junction temperature of the light emitting element in the light emitting device is controlled in a range of 100 ° C. to 150 ° C. 5.   The energization time of the current that is intermittently energized by the second control means is in the range of 1 second to 10 seconds, and the current interruption time is in the range of 1 second to 10 seconds. 4. The test apparatus according to any one of 4.   The current intermittently energized by the second control means until the rise time when increasing from 10% of the maximum value of the current signal to 90% and decreasing from 90% to 10% of the maximum value of the current signal. The test apparatus according to any one of claims 1 to 5, wherein the fall time is controlled within 100 milliseconds.   The maximum value of the surge current added to the current during energization by the second control means is controlled within 10% of the current value during energization. The test apparatus described.   A light emitting device is installed inside a test tank, and the temperature and humidity inside the test tank are controlled, and the light emitting device is intermittently energized to check for deterioration of the light emitting device. Test method.   The test method according to claim 8, wherein the current is intermittently supplied in a range where the temperature of the sealing resin of the light emitting device does not exceed the glass transition temperature.

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