CN105301468A - Method for detecting heat dispersion of LED chip or package - Google Patents
Method for detecting heat dispersion of LED chip or package Download PDFInfo
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- CN105301468A CN105301468A CN201410275560.8A CN201410275560A CN105301468A CN 105301468 A CN105301468 A CN 105301468A CN 201410275560 A CN201410275560 A CN 201410275560A CN 105301468 A CN105301468 A CN 105301468A
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- led chip
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- junction temperature
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Abstract
The present invention discloses a method for detecting heat dispersion of an LED chip or package. The present invention provides a novel method for assessing good or bad of heat dispersion of the LED chip or package product on the basis of the dependent relation of junction temperature and time of the LED chip or package. A dynamic curve of junction temperature (T) and time (t) is acquired through the change of the input voltage of the LED chip or package with the passage of time during the period from starting time to stable time by the combination of a relationship curve of the forward voltage and junction temperature of the LED chip or package, and the curve is fitted by the utilization of indexes so that the coefficient of heat dispersion for assessing good or bad of heat dispersion of the LED chip or package is acquired. The method for detecting heat dispersion of the LED chip or package system is convenient and rapid to determine heat dispersion of the LED chip or package system, and has great significance for learning the reasonability of the heat dispersion structure of the LED chip or package and saving cost.
Description
Technical field
The present invention relates to the detection technique of semiconductor luminous chip (LED) heat dispersion, refer to a kind of method detecting LED chip or package cooling performance especially.
Background technology
LED is a kind of light emitting semiconductor device, and its luminous base reason belongs to electroluminescence.Owing to form in the physical characteristics of LED chip layers of material and Material growth process the reasons such as lattice mismatch between layers, cause the electronics that inputs under outside electric field action and hole to only have small part can be converted into the form of light in the compound of luminescent layer, all the other most heats are converted to heat energy.
Early stage light-emitting diode luminous efficiency is very low, its structure adopted and general-purpose diode similar, luminous flux only has per mille lumen, and the heat of generation is little, does not need to consider heat dissipation problem.But along with the large-scale application on LED of micro-, nanometer technology and electronics integrated technology, high-power, ultra-brightness LED product continues to bring out, and the heat radiation how effectively improving LED is more and more subject to industry and pays close attention to.
Along with the change of temperature, its characteristic has obvious change.This change is mainly reflected in the following aspects: 1) the interior quantum combined efficiency of LED reduces, and causes change and the decay of device luminescent properties; 2) will shorten actual life; 3) there is obviously drift in the color of LED light.These change the illuminating effect that will have a strong impact on LED illumination product.
The heat-sinking capability of LED chip or encapsulation and selected backing material, encapsulating material and to be used for the factors such as the mode connecting different Heat Conduction Material interface relevant.Therefore, heat radiation also just becomes a key factor of great power LED application, and how effectively detecting semiconductor luminous chip/package cooling performance just becomes LED and apply problem anxious to be resolved.
Improve the most direct method of heat radiation be exactly by good heat radiation structure design LED chip or be encapsulated in normal work time the heat that produces effectively distribute.Understand the radiator structure performance condition of LED chip or encapsulation, the detection method that one good must be had, therefore, find a kind of can not only fast but also the method simply measuring LED chip or package cooling performance quality seem particularly important, especially different to same type product heat radiation configuration designs.At present, concerning LED chip or encapsulation, LED chip or the interior junction temperature detection method of encapsulation have, but also do not have a kind of method that simple, effective detection LED chip or package cooling performance are carried out.
Summary of the invention
Object of the present invention is exactly to propose a kind of simple, effective method detecting LED chip or package cooling performance, determines that its heat dispersion is good and bad by measuring LED chip or encapsulating temperature rise curve.
To achieve these goals, technical scheme of the present invention is as follows: a kind of method detecting LED chip or package cooling performance, is characterized in that said method comprising the steps of:
A, put in integrating sphere by tested LED chip or encapsulation, connect the power supply with direct current output function, make LED chip or encapsulation can by normal mode of operation work, time initial, power switch be in off state;
B, open the working power of LED chip or encapsulation, open moisture recorder in integrating sphere, integrating sphere environment temperature before working power is connected in record LED chip or encapsulation;
C, open the working power of LED chip or encapsulation, work under making LED chip or being encapsulated in setting electric current, voltage instrument and moisture recorder just record from LED chip or encapsulation start luminous temperature value in the LED chip in each moment or the input voltage value of encapsulation and corresponding ball backward, until LED chip or encapsulation reach normal table duty;
D, utilize the measurement mechanism of LED forward drop and junction temperature curve, obtain the V of this LED chip or encapsulation forward voltage and LED chip or packaged LED junction temperature
f-T
jrelation curve;
E, the V utilizing step D to obtain
f-T
jrelation curve, finds the changes delta V of the forward voltage values caused by change of different time integrating sphere environment temperature after the unlatching working power of LED chip or encapsulation
f1, Δ V
f2, Δ V
f3Δ V
fn;
F, to LED chip or encapsulate actual input voltage value and revise; Then, the V again utilizing step D to obtain
f-T
jrelation curve, obtains not the LED chip under revised LED chip or the actual input voltage value of encapsulation in the same time or encapsulates junction temperature;
Junction temperature T corresponding to G, each moment obtained by step F is ordinate, and horizontal ordinate is time t, defines junction temperature temperature rise relation curve in time under LED chip or encapsulation normal operating conditions;
H, formula T=A+B × exp (-C × t) is utilized to carry out the Fitting Calculation to described temperature rise relation curve, wherein T and t represents LED module junction temperature and time in LED chip or encapsulation, A, B and C are Fitted parameters, by just obtaining this LED chip or encapsulation effective heat dissipation coefficient C after matching.
The present invention proposes to obtain the new method of LED chip or encapsulating products heat dispersion quality based on LED chip or encapsulation junction temperature and time-dependent relation.By LED chip or encapsulation from being opened in stabilization time input voltage over time, in conjunction with LED chip or encapsulation forward voltage and junction temperature curve, obtain the performance graph of junction temperature (T) and time (t), this curve of utilization index matching obtains the coefficient of heat transfer characterizing this LED chip or package system heat dispersion.Method of the present invention considers the impact of measures ambient temperature on test result, for test LED chip or package cooling performance quality provide new approach, has simple to operate, is with a wide range of applications.The present invention can determine the heat dispersion of LED chip or package system easily and fast, for understanding LED chip or package cooling performance all significant.
Accompanying drawing explanation
Fig. 1 is the LED 1 sample junction temperature temperature rise curve in time in normal operation that the present invention records, represented by stain, provided by blue line with the curve that the exponential formula matching provided in instructions obtains, obtaining the parameter C value relevant with encapsulating 1 heat dispersion by matching is 0.024.
Fig. 2 is the LED 2 sample junction temperature temperature rise curve in time in normal operation that the present invention records, represented by stain, provided by blue line with the curve that the exponential formula matching provided in instructions obtains, obtaining the parameter C value relevant with LED 2 heat dispersion by matching is 0.011.
Embodiment
By the following examples and accompanying drawing the present invention is described in further detail.
The present invention obtains the parameter relevant with heat dispersion by matching LED chip or the temperature rise curve that encapsulates junction temperature in normal working conditions.Be below concrete case study on implementation, relevant embodiment can be understood in case study on implementation:
Embodiment 1:
LED, is encapsulated as detected object by 1WLED, and concrete measuring process is as follows:
Concrete steps of the present invention are as follows:
1, tested LED chip or encapsulation are put in integrating sphere, connect the power supply with direct current output function, power supply is in direct current supply state, making LED chip or encapsulate can by normal mode of operation work, and time initial, power switch is in off state;
2, open the working power of LED chip or encapsulation, open moisture recorder in integrating sphere, working power forecourt environment temperature (T is connected in record LED chip or encapsulation
0), be T in the present embodiment
0=25.1 degrees Celsius;
3, the working power of LED chip or encapsulation is opened, work (such as: 350mA) under the watt current that LED chip or encapsulation are claimed according to enterprise, voltage instrument and moisture recorder just record from LED chip or encapsulation start luminous the LED chip in each moment or the input voltage value (V of encapsulation backward
1, V
2v
n) and corresponding ball in temperature value.The input voltage value of LED chip or encapsulation and integrating sphere environment temperature value should records simultaneously, and with one_to_one corresponding writing time, writing time, interval should be short as far as possible, until LED chip or encapsulation reach normal table duty.In this example, data writing times is 1 time/10 seconds, until LED chip or encapsulation reach the junction temperature steady state (SS) under normal operating conditions, to ensure that all processes that LED chip or encapsulation are risen due to LED junction temperature after having added working current has all gone on record; Wherein the decision principle of steady-working state is according to international standard IEC62671 " general lighting LED module performance requirement ": carried out light output measurement at interval of 1 minute, reaches stable if thought when the maximum light output recorded in 15 minutes and minimum light output reading value (maximum-minimum) are less than 0.5%;
4, adopt Chinese utility model patent " measurement mechanism of LED forward drop and junction temperature curve " (patent No.: ZL.200920212653.0), obtain the V of this LED chip or encapsulation forward voltage and LED chip or packaged LED junction temperature
f-T
jrelation curve;
5, the V utilizing step 4 to obtain
f-T
jrelation curve, finds the changes delta V of the forward voltage values caused by change of different time integrating sphere environment temperature after the unlatching working power of LED chip or encapsulation
f1, Δ V
f2, Δ V
f3Δ V
fn;
6, to LED chip or encapsulate actual input voltage value and revise, revised LED chip or the actual input voltage value of encapsulation should be V
t1-Δ V
f1, V
t2-Δ V
f2, V
t3-Δ V
f3v
tn-Δ V
fn; Then, step 4 is again utilized to obtain V
f-T
jrelation curve, obtains not the LED chip under revised LED chip or the actual input voltage value of encapsulation in the same time or encapsulates junction temperature;
Junction temperature T corresponding to each moment 7, obtained by step 6 is ordinate, and horizontal ordinate is time t, defines junction temperature temperature rise in time (T-t) relation curve under LED chip or encapsulation normal operating conditions;
8, utilize business-like software Origin to carry out the Fitting Calculation to curve formula T=A+B × exp (-C × t), wherein T and t represents LED module junction temperature and time in LED chip or encapsulation, and A, B and C are Fitted parameters.By this LED chip or encapsulation effective heat dissipation coefficient C just can be obtained after matching.The size of C value has reacted the quality of this LED chip or encapsulated radiating structure validity.C value is larger, illustrates that this structure thermal diffusivity is better.
Embodiment 2:
LED 1 in LED in embodiment 2 and embodiment 1 is all the LED chip using equal-wattage, and difference is different at packing forms.
Concrete measuring process is identical with embodiment 1, and the LED chip finally obtained or the encapsulation 2 parameter C value relevant with heat dispersion are 0.011.The C value 0.024 having this C value to give LED chip in embodiment 2 or the relevant coefficient of package cooling performance to be less than LED chip in embodiment 1 or encapsulation, can think that LED chip in embodiment 1 or package cooling successful are better than LED chip in embodiment 1 or encapsulation for this reason.
Above-described embodiment is only in order to illustrate technological thought of the present invention and feature; its object is to enable those of ordinary skill in the art understand content of the present invention and implement according to this; the scope of this patent is also not only confined to above-mentioned specific embodiment; namely all equal changes of doing according to disclosed spirit or modification, be still encompassed in protection scope of the present invention.
Claims (1)
1. detect a method for LED chip or package cooling performance, it is characterized in that said method comprising the steps of:
A, put in integrating sphere by tested LED chip or encapsulation, connect the power supply with direct current output function, make LED chip or encapsulation can by normal mode of operation work, time initial, power switch be in off state;
B, open the working power of LED chip or encapsulation, open moisture recorder in integrating sphere, integrating sphere environment temperature before working power is connected in record LED chip or encapsulation;
C, open the working power of LED chip or encapsulation, work under making LED chip or being encapsulated in setting electric current, voltage instrument and moisture recorder just record from LED chip or encapsulation start luminous temperature value in the LED chip in each moment or the input voltage value of encapsulation and corresponding ball backward, until LED chip or encapsulation reach normal table duty;
D, utilize the measurement mechanism of LED forward drop and junction temperature curve, obtain the V of this LED chip or encapsulation forward voltage and LED chip or packaged LED junction temperature
f-T
jrelation curve;
E, the V utilizing step D to obtain
f-T
jrelation curve, finds the changes delta V of the forward voltage values caused by change of different time integrating sphere environment temperature after the unlatching working power of LED chip or encapsulation
f1, Δ V
f2, Δ V
f3Δ V
fn;
F, to LED chip or encapsulate actual input voltage value and revise; Then, the V again utilizing step D to obtain
f-T
jrelation curve, obtains not the LED chip under revised LED chip or the actual input voltage value of encapsulation in the same time or encapsulates junction temperature;
Junction temperature T corresponding to G, each moment obtained by step F is ordinate, and horizontal ordinate is time t, defines junction temperature temperature rise relation curve in time under LED chip or encapsulation normal operating conditions;
H, formula T=A+B × exp (-C × t) is utilized to carry out the Fitting Calculation to described temperature rise relation curve, wherein T and t represents LED module junction temperature and time in LED chip or encapsulation, A, B and C are Fitted parameters, by just obtaining this LED chip or encapsulation effective heat dissipation coefficient C after matching.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410275560.8A CN105301468A (en) | 2014-06-19 | 2014-06-19 | Method for detecting heat dispersion of LED chip or package |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410275560.8A CN105301468A (en) | 2014-06-19 | 2014-06-19 | Method for detecting heat dispersion of LED chip or package |
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|---|---|
| CN105301468A true CN105301468A (en) | 2016-02-03 |
Family
ID=55198963
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|---|---|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106449453A (en) * | 2016-09-29 | 2017-02-22 | 通富微电子股份有限公司 | Detection method for natural-convection heat exchange coefficients and thermal resistance of semiconductor package body |
| CN112114271A (en) * | 2020-08-24 | 2020-12-22 | 厦门多彩光电子科技有限公司 | Method for evaluating quality of LED chip |
-
2014
- 2014-06-19 CN CN201410275560.8A patent/CN105301468A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106449453A (en) * | 2016-09-29 | 2017-02-22 | 通富微电子股份有限公司 | Detection method for natural-convection heat exchange coefficients and thermal resistance of semiconductor package body |
| CN106449453B (en) * | 2016-09-29 | 2019-02-22 | 通富微电子股份有限公司 | A kind of NATURAL CONVECTION COEFFICIENT OF HEAT of semiconductor package body and the method for detecting of thermal resistance |
| CN112114271A (en) * | 2020-08-24 | 2020-12-22 | 厦门多彩光电子科技有限公司 | Method for evaluating quality of LED chip |
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Application publication date: 20160203 |