Hardware-software complex for quality control of LEDs according

to thermal characteristics

CeBIT-2014

KOTELNICOV INSTITUTE of Radio Engineering and Electronics

of the Russian Academy of Sciences

(Ulyanovsk Branch)

Unique Systems

and Technologies

Typical construction of semiconductor devices on the radiator

Thermal model of semiconductor devices

Figure 2. Simple model of a real

physical structure Figure 3. Foster (a.) and Cauer (b.)

type representation of physical

structures with finite time constants

a.)

b.)

Standard methods

of thermal resistance measurement

Method on Russian Standard

Method on EIA/JEDEC Standard

Method on NIST Standard (US)

Method on MIL Standard (US)

Fundamental documents

The following documents are recommended reading for reference and test method standard description purposes:

Mil Std 883C Method 1012.1 Thermal Characteristics of Microelectronic Devices

SEMI Test Method #G43-87 Test Method, Junction-to-Case Thermal Resistance Measurements of Molded Plastic Packages

SEMI Test Method #G38-87 Still and Forced Air Junction-to-Ambient Thermal Resistance Measurements of Integrated Circuit Packages

SEMI Test Method #G42-88 Specification, Thermal Test Board Standardization for Measuring Junction-to-Ambient Thermal Resistance of Semiconductor Packages

SEMI Test Method #G30-88 Junction-to-Case Thermal Resistance Measurements of Ceramic Packages

SEMI Test Method #G32-86 SEMI Guideline for Unencapsulated Thermal Test Chip

SEMI Test Method #G46-88 Thermal Transient Testing for Die Attachment Evaluation of Integrated Circuits

EIA JEDEC EB-20 Accepted Practices for Making Microelectronic Device Thermal Characteristics Test

NIST Special Publication 400-86 Semiconductor Measurement Technology: Thermal Resistance Measurements

Diagrams, described the method

of JEDEC Standard 51-1

Time

Time

VH

0

IH

0

VFD

V

I

t0 t1 t2 t3

EIA/JEDEC Standard No. 51-1

Page 10

Thermal transient tester T3Ster

(Analog, produced by MicRed Co, cost about $100 000)

An automated photometric/radiometric measurement setup with a Peltier-cooled

LED fixture, used in connection with the T3Ster thermal transient tester

Heating curve of LED in logarithmic scale

Simulated thermal impedance plots at the three junctions

of the LED module in still air, green LED driven

Step responses

Device for measuring thermal impedance

of light emitting diodes LED-meter

Functional scheme of LED meter

Principal of thermal impedance determination

Thermal impedance is based on transmitting the electric pulse through the light emitting diode with the pulse-duration that is modulated according to harmonic law, and measuring the corresponding changes of the heterojunction temperature relative to the case or ambient.

On the basis of calculating the magnitude and phases of the first harmonics of heating power and temperature of heterojunction the module of thermal impedance is determined, as well as the phases shift between the temperature and the heating power.

Principal of thermal impedance determination

Thermal impedance is based on transmitting the electric pulse through the light emitting diode with the pulse-duration that is modulated according to harmonic law, and measuring the corresponding changes of the heterojunction temperature relative to the case or ambient.

On the basis of calculating the magnitude and phases of the first harmonics

of heating power and temperature of heterojunction the module of thermal

impedance is determined, as well as the phases shift between the temperature

and the heating power.

Diagrams of measurement signals

Features

The measurement of module and phase of the thermal impedance with different heating currents and frequencies of switching the heating power.

The measurement of thermal resistance of all the links of the thermal path of light emitting diodes: heterojunction – heat sink – circuit plate (soldering point) – radiator – ambient. This provides an opportunity to design lighting products with the most effective heat sink.

The measurement of overheating temperature of the crystal relative to the ambience medium.

The presentation of the measurement results in the form convenient for analysis and saving the results in the computer memory.

Computer interface of LED meter

Technical characteristics

Range of thermal impedance – from 0,1 up to 1000 K/W

Magnitude of the heating impulses of current – from 10 mA up to 1100 mA

Frequency of switching the heating power – from 0,001 Hz up to 800 Hz

Measurement error of thermal impedance – 2%

Power supply 220 V through the adaptor with output voltage +48 V

Wattage – less than 20 W

The overall device size –190x140x40 cm

The weight together with adapter – 0,6 kg

Technical specification and User's Guide: http://ctt.ulstu.ru/cebit_2014/ust-control_LEDs.pdf

Electrothermal model of structure

of a heterojunction light-emitting diode

Model

The equations of an electrothermal feedback:

Restrictive condition:

Structure

z

x

y

q(T, J)

Lx

Ly

0

Lz1

Lz2

heat sources

heterostructure

[InGaN/GaN]

substrate

[Al2O3]

heat sink

electric

power

Solution and calculated results

0.05 0.1 0.15 0.2 0.25 0.3 4

6

8

10

1 - = 0;

2

- = ( J,T);

3 - = ( T);

4

- = ( J);

5 - = const;

1

2

3

4

5

J, А/мм2

0 I, mA

RTj-c, К/W

100 200 300 400 500 600

3

4

6

5

7

Current dependences of thermal

resistance of power LED

Customers, partners and awards

The device was ordered by:

Concern JENOPTIC (Germany);

JSC Svyaz Engineering (Moscow);

Institute of Physics and Technology of RAS (Saint-Petersburg);

Research Institute of Semiconductors (Tomsk);

Moscow State University, Faculty of Physic; Ulyanovsk State Technical University

AWARDS:

Gold Medal at the International Exhibition 2012, IENA

DIPLOMA at the at the International Exhibition 2012, Moscow

Grant 2012 START Program

Awards on international exhibitions

Contacts

Small Innovative Enterprise

“Unique Systems and Technologies”

Mr. Vyacheslav Sergeev,

E-mail: sva@ulstu.ru

Ulyanovsk Centre for Technologies Transfer

Phone, fax: (8422) 77-81-92

E-mail: ctt@ulstu.ru, http://ctt.ulstu.ru

32, Severny Venets st., Ulyanovsk, Russia,

432027.