This standard specifies the test method for the steady-state thermal resistance and transient thermal impedance of semiconductor diodes. This standard is applicable to the test of the steady-state thermal impedance of rectifier diodes, transient voltage suppression diodes, power Zener diodes and some Zener, signal and switching diodes. SJ 20788-2000 Test method for thermal impedance of semiconductor diodes SJ20788-2000 Standard download decompression password: www.bzxz.net

Military Standard of the Electronic Industry of the People's Republic of China FL5961
SJ20788—2000
Measurment method for thermal impedance of semiconductor diodesPublished on 2000-10-20
Implementation on 2000-10-20
Approved by the Ministry of Information Industry of the People's Republic of China Military Standard of the Electronic Industry of the People's Republic of China Test Method for Thermal Impedance of Semiconductor Diodes
Measurment method for thermal impedance of semiconductor diodes1 Scope
1.1 Subject content
This standard specifies the test method for steady-state thermal resistance and transient thermal impedance of semiconductor diodes 1.2 Scope of application
SJ20788—2000
This standard applies to the test of steady-state thermal resistance and transient thermal impedance of rectifier diodes, transient voltage suppression diodes, power Zener diodes and some Zener, signal and switching diodes. 1.3 Application Guidewww.bzxz.net
Transient thermal testing, known as a product screening process, is a branch of thermal impedance testing that determines the thermal conductivity of the diode die to base interface and is a measure of the thermal conductivity of the die attach. It is suitable for product screening processes. This method can be used to determine the design of the base or thermal conductive pins with respect to mass (weight) and thermal conductivity: and can identify the quality of die attach. This is particularly applicable to power devices. This method can be used for product monitoring, incoming inspection and pre-burn-in screening. Some Zener structures, especially when small junction area designs are used, cool too quickly due to the heating current when the diode forward current is tested to provide an accurate measurement. For such devices, a method is provided to apply current in the Zener direction and measure closest to the termination of the heating current. In this method, minority carriers are not included and the inductive effect is minimized due to the small current. This method can be considered a laboratory measurement because the cable has a certain length in automatic testing, which will prevent measurement at the termination of the heating current and thus affect the measurement accuracy. This test method is intended for use in initial design verification of Zener devices with forward thermal impedance testing (e.g., automated testing) that corresponds to previously established production test limits. In forward production assurance, it must be ensured that the reverse (Zener) thermal impedance does not exceed the specified limits. If the Zener test method exceeds the forward method by 10% or more, then for these devices, the limits for production monitoring (forward automated testing) may be reduced according to this more accurate laboratory method (see 5.3.1).
The steady-state thermal resistance and transient thermal impedance of semiconductor devices are sensitive to voids in the die attach material between the semiconductor die and the package because these voids impede the flow of heat from the die to the substrate (package). Because of the different thermal time bands between the die and the package, transient thermal response measurements are more sensitive to the presence of voids than steady-state measurements. This is because the thermal time constant of the chip is generally several orders of magnitude smaller than that of the package. Therefore, the heating power pulse width can be selected so that it is slightly greater than the thermal time constant of the chip and smaller than the thermal time constant of the package (substrate). In this way, during the heating pulse time, only the chip and the interface between the chip and the substrate are heated. For various tube and shell designs, a heating power pulse width of 1 to 400ns can meet this criterion. This greatly increases the detection capacity of voids. Another advantage is that the device under test does not need to be heated separately. However, transient thermal impedance or thermal response technology is a less time-consuming technology and can be used as a screening, sequence control or advanced inspection and testing in manufacturing. 2 Referenced documents GB128A--97 Test methods for discrete semiconductor devices 3 Definitions This standard adopts the definitions in GJB128A. 3.1 Parameter symbols The parameter symbols used in this forward test method are as follows (when using the Zener method, see the notes in this chapter): a. VF: The device under test that is sensitive to the junction temperature b.4V: Change in the temperature-sensitive parameter V due to the application of thermal power to the device under test. I: Current applied to the device under test during the heating time period to produce power dissipation. c.
d. Vi: The heating voltage introduced by the application of current to the device under test, PH: The product of the heating power pulse value and Vu. e.
: The duration for which P is applied to the device under test. f.
g, 1g: The measurement current applied to the forward biased temperature-sensitive diode junction to measure V. h:tun: The measurement delay time from the removal of the heating power (PH) to the last V test time (see tw).
i.tsw: sampling window time, during which the final VFr measurement is made. The tsw value should be as small as possible. When measured with an oscilloscope, sw can be close to zero.
j. VTC: voltage temperature coefficient of V, with respect to T, at a fixed IM value, in mV/K. k. K: thermal calibration coefficient, equal to the reciprocal of VTC, in K/mV. I, CU: comparison unit. Equal to divided by V, the transient thermal response is the normalization of the change in dissipated power, in mVV.
mT: junction temperature of the device under test.
n. 4: change caused by the application of P, time equal to. 0. Zhji-x: thermal impedance at a certain time from the device junction to a determined reference point, in K/W. Zm -: Thermal impedance measured from the device junction to a point on the outer surface of the tube case directly adjacent to the device chip, using a time equal to the device's time constant, in K/W. p, Riti-x: Thermal resistance from the device junction to a determined reference point, in K/W. Ri-: Thermal resistance from the device junction to a point on the outer surface of the tube case directly adjacent to the device chip, in K/W.
Rthi- Thermal resistance from the device junction to the environment, in K/W. Note: ①) When the Zener method is used, wherever the following definitions appear in this standard, corresponding changes shall be made to the academic symbols: Change to
Vg Change to VzL
Vn Change to VzH
Vei Change to VzLi
Ver Change to VzLt
SJ 20788--2000
Phrase: Forward bias is changed to reverse bias. When the Zener method is used, the AK, K and CU parameter values ​​should be significantly different from those of the forward bias method. Different nominal Zener voltages will also have some differences. 4 General requirements
The general requirements of the test should comply with Chapter 4 of GJB128A 5 Test equipment
The equipment required for this test should include the following equipment (configured as shown in Figure 1) applicable to the specified test steps: S
Figure 1 Thermal impedance test device for diodes
5.1.1 Constant current source, with the ability to calibrate the I value and provide the V value required by the device under test. During the entire heating time, the constant current source should be able to maintain the current within a 2% error. 5.1.2 Apply a 1M constant current source with sufficient voltage margin to fully conduct the TSP (temperature sensitive parameter) junction. 5.1.3 The switching time of the electronic switch that can switch between the heating state and the measuring state should be short enough to avoid cooling of the device under test during the switching period. The typical requirement for the switching time should be in the range of several microseconds or several + microseconds. 5.1.4 The voltage measurement circuit should have a millivolt resolution for measuring Vft. 5.2 Test method
During the test, first adjust IM and Im to the required values. The value is usually at least 50 times larger than the IM value. Then, put the electronic switch in position 1 and measure the VE value. Move the switch to position 2 again for a duration equal to and measure the Vu value. At the end, move the switch to position 1 again and measure V within the time period determined by mp (or tmp plus tsw). The two constant current sources should be turned off when the test is completed. The thermal impedance test waveform is shown in Figure 2. It should be short enough and should be controlled in the range of several + milliseconds. -3-
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SJ 20788-2000
Forward bias method
Zener bias method
Figure 2 Thermal impedance test waveform
Method: ① Some test instruments can directly provide
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