Issue B 0507

Page 9 of 11

OPTEK reserves the right to make changes at any time in order to improve design and to supply the best product possible.

OPTEK Technology Inc. — 1645 Wallace Drive, Carrollton, Texas 75006

Phone: (972) 323-2200 or (800) 341-4747 FAX: (972) 323-2396 visibleLED@optekinc.com www.optekinc.com

10-Watt Lednium SMD

OVTL09LG3x Series

Typical elements in the conducting path and corresponding nominal thermal conductivities are:

Elements

w/mK

Epilayers

GaN/InGaN

150

Substrate

Sapphire

50

Die attach material

Conductive epoxy

10

Package

Silver plated copper

350

Solder

Solder (Sn/Ag/Cu)

35

Copper cladding

Copper

300

Note : Thermal conductivity is a physical constant. For the materials above, the respective contribution each makes

Thermal Conductivity (TC) is defined to be the heat conducted in time (t), through thickness (T) in a direction normal

to a surface area (A), due to a temperature difference (δT).

Therefore

TC= q/t x {T/[A x δT]}

and

δ

T = [Q x T]/[A x TC]

where δT = Temp. difference (K)

Q = Power (w)

A = Surface area (m

T = layer thickness (m)

TC = Thermal Conductivity (w/mK)

Theoretical Calculation (for 1 watt dissipated in a cup product via a single 40mil die)

GaN

Thickness approx 10 x 10

-6

= 1 x 10x10

Area 10

-6

= 0.07 K

Substrate

T = 60 x 10

-6

= 1 x 60x10

= 1.2 K

Die attach

T = 20 x 10

-6

= 1 x 20x10

A = 2 x 10

-6

= 1

Package

T = 0.4x10

-3

= 1 x 0.4x10

A = 6x10

-6

= 0.19

Solder

T = 60x10

-6

= 1 x 60x10

A = 6x10

-6

= 0.4

Total Calculated δT = 2.86K