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Semiconductor Packaging for

High Power Diode Lasers

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Requirements

High volumeCost efficientReliableInnovative

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Considerations

Mechanicaldifferent materials with distinct properties at different conditions (-40°C…+125°C)Electricalhigh current at low voltage or internal conversionOpticalhigh intensity light source needs low/zero absorption materialsEconomicalthe concept must work and must be affordable

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Examples

Smart laser.pulse laser for peak pulses up to P=100W withinternal driver circuit

ACC - pulse laser modulepulse laser-bar with 12 channels on PCB for SMT packaging

Sirilas®cw-laser module on TO263 lead-frame technology

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Smart laser package:

High currentHigh peak optical loadCurrent / voltage conversionMass production

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Smart laser – general performance

70

80

90

100

110

0 250 500 750 1000

time [h]

Pop

t_de

t [%

] .

h 80 W @ 100° C ambient temp.

h hardly any degradation at high power level and high temperature

50

75

100

-25 25 75 125T [°C]

P [W

] 50A

Pw = 50 ns

ν = 1 kHz

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Smart laser - components

Lead frame

Laser chipCapacitorsFET

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Smart laser - die bonding

Laser die

FET

Capacitor for charge acc

Capacitor for charge acc

Die bonding: - standard process,- uses often conductive glue- high throughput and highly automized

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Smart laser - wire bonding

Laser die

FET

Capacitor for charge acc

Capacitor for charge acc

Wire bonding: - standard process,- using Alu or Au wire- high throughput

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Smart laser - casting

Casting:Resin needs to grant: protection

against mechanical forcesagainst humidityagainst solvents

while offering good light output andgood stability at all temperatureswithout damaging device and package

Lead frame afterdie and wire bonding

Casting form filledwith resin

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Smart laser - singulation and testingLL90_3

3 samples, Lot 01-17-01, 30ns, 1kHz, 25°C

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35

Charge Voltage, V

Opt

ical

Pow

er, W

1

2

3

Singulation (after casting) and testing. Depicted is a measurement that showsthat the laser is operated at high voltage

Finished package after casting

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Package for pulse laser array:

High currentHigh optical loadMultiple channelAutomotive qualification

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Application: Laser range finder

Detects distance and velocity relative to thecar driving ahead⇒ Enables automatic Save Distance control⇒ Range 100 - 200 m

0

40

80

120

0 10 20 30 40 50current [A]

Pea

k-P

ower

[W] 3

2

1

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ACC Pulse Laser Arrays: die bonding

PCB panel for easy handling and parallel processing. Offers platformduring assembly and operation.

NTC for temperature control. Assemblyusing conductive glue. Wide positiontolerances. Simple process.

Submount assembly using conductiveglue. Very large die (1mm x 5mm) andtherefore difficult handling. Medium requirements for placement accuracy.

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ACC Pulse Laser Arrays: wire bonding

Die bonding laser barsdifficult since sensitive, large chip has to be placed withexcellent accuracy forproper fit to external optics.

Wire bonding:Standard process in BE production BUT:- bonding on emitter – risk of damage of die (cratering)- many channels – need to avoid cross talk and s.c.- only one wire / emitter – high current (50A / 50µmØ)

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ACC Pulse Laser Arrays: housing and separation

Housing assembly:Gluing PCB to housing. Risc of damaging die or wire bonds.

Punching of PCB for separation of individual units out of frame. Riscof bending PCB and loosing glueinterface

Fit housing – PCB:Tight fit requires tight specificationsand tight manufacturing specs for housing and PCB mechanicalinterfaces: Holes in PCB and postsin housing

Tracing:For later reference, all samples must betraceable. Therefore logisticdrops in at this working step.

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Package for CW Laser:

High heat loadHigh currentHigh optical load

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Application: Hardening

2 x 1.5 kW

99% availability

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Package Concepts

FAC lensα matched Heatsink

Laser bar – 16 emitter

Gold Wires

MCC Sirilas ®individual pieces volume concept

Laser bar

Mechanical fixture

waterin/out lets

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Interfaces : Current, heat, light

Drive current:35 .. 40 A @ 2 V

Optical outputpower:up to 30W cwNA < 0.1

Thermal load: 40 to 50 W Rth ≈ 0,6 K/W

Water cooling

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Package Technology

High temperaturepremold TO263 type leadframe

Laserbar

Heatsink

Cylindrical lens

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Optical properties: collimated beam

Laser source CylindricalLens

Window

Raytrace simulation

Need to offer good beam quality and to avoid waste heating of package.

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Assembly: die and wire bonding

After wire bonding and lens assemblyDie bonding:

Wire bonding:

Laser bar lens

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• ITH = 8.4 A

• η = 1.28 W/A

• RS = 4,4 mΩ

6.4mm Laser bar @ 50 W opt power: • IOP = 48,5 A• UOP = 1.81 V• WPE = 58.6 %

L-I-V characteristics

0

0,4

0,8

1,2

1,6

2

2,4

0 10 20 30 40 50Current, A

Vol

tage

/ V

0

10

20

30

40

50

60

Pow

er /

W; W

PE

/ %

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Reliability: Intermittent CW

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0,0 4,0 8,0 12,0 16,0 20,0 24,0 28,0 32,0 36,0 40,0

MShot

Popt

[nor

m.]

Wear out failures ( Degradation ) t50% = 62 MShotRandom failures with. open contact not seen yet

Iop=0A..36A

Using hard solder and CTE matched submount reduces stress and allows for excellent reliability. Up to now, no spontaneous failure.

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Summary

Diode lasers are used for many distinct applications(sensing, illumination, direct application…)

They operate in a very wide range of environmentalconditions (-40°C….+125°C, humidity, …)

Different kind of packages have been developed(high volume, highly specialized, optics, SMT….) for optimal use of die capabilties.