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Novel Low Inductive Phase-Leg IGBT Module Eases ParallelingABB has introduced the LinPak, a new open standard phase-leg type IGBT power module with a rating of1700 V and 2 x 1000 A and a footprint of 100 mm x 140 mm. This type of module will set a new standardin power density. LinPak is designed to accommodate chipsets from 1200 V up to 3300 V. A 3300 Vmodule version will follow early next year. Raffael Schnell, Samuel Hartmann, Dominik Trüssel,Fabian Fischer, Andreas Baschnagel and Munaf Rahimo, ABB Switzerland Semiconductors

The LinPak IGBT module features anexceptionally low stray inductance enablingthe full utilization of advanced lowswitching loss IGBT chipsets and even

future full Silicon Carbide switch solutions.In addition the LinPak is ideally suited forparallel connection with negligible derating,thus a large range of inverter power can be

realized with just one module type.Together with the open standard conceptthis module fulfills a long wish of theindustry in nearly all high power segmentssuch as traction and CAV (commercial,construction and agricultural vehicles),wind-power and solar and industrial drivesto name a few.

Open standard approachPresent IGBT module solutions are at itslimit when it comes to advanced and fasterIGBT/diode chipsets since the overall strayinductance per switched ampere is toolarge and high over-voltage will occur. Inaddition, the available electrical contactarea of today’s modules is limited anddates back to times when the packageswere rated with 50 % less current thannow. Due to today’s modules’ lack ofscalability, a large variation of outlines existto match various inverter ratings. Thepresented LinPak module concept (Figure1) addresses all these issues and ispublished as an open standard, meaningmodule manufacturers can freely adoptthe outline and customers benefit from astandard solution provided by more thanone supplier making inverter designseasier. The LinPak offers as well exceptional low

stray inductance of 10 nH and an easycustomer interface enabling theconstruction of a very low inductive DCconnection with sufficient contact area forthe high current densities. This is the idealfit for the full utilization of the advancedfast IGBT/diode chipsets such as the latest1700V SPT+ technology. It also makes thepackage fit for future hybrid and full SICsolutions that come with much higherswitching speeds.Besides the very advanced and novel

package concept, the LinPak features

Figure 1: ABB’s low inductive LinPak IGBT module for reliable high-power converters

Figure 2: LinPak scalability

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ultra-sonic welded terminals and anadvanced high reliability solder jointbetween the AIN substrate and AlSiCbaseplate material combination. Inaddition, the well-established hightemperature cycling capable bondingtechnique and the gate-print to substratealuminum bond interconnect from theimproved HiPak are incorporated in thenew LinPak design.

Module scalability and record currentdensityThe LinPak module type offers the benefitthat just one module type is needed pervoltage rating. Thanks to a homogenouscurrent path concept, the module enablesparallel connection of more than fourmodules without any significant derating(Figure 2). The current density offers asolid improvement of more than 10 %

compared to older module types on themarket as shown in Table 1.

Mechanical concept and connectionsThe gate-unit connection is realized with asimple adapter-board (PCB) directlymounted onto the module between ACand DC terminals. The connection to theauxiliary terminals for gate, emitter,collector and thermistor are realized withM3 screws. In addition, four molded M3nuts are positioned in the corners tomechanically fix the adapter board inharsh environmental applications liketraction or CAV. The adapter-boardconnects the modules’ gates and auxemitters in parallel. Thus, many modulescan be connected in parallel with just onegate-unit.The power connections are designed to

enable an absolute symmetrical DC

connection, which is crucial for excellentcurrent sharing. The creepage andclearance distances are designedaccording to IEC 60664-1 and EN 50124-1 for functional insulation up to a devicerating of 3300 V.The LinPak offers the highest contact

area per rated current. Table 2 comparesthe current per M8 screw for variouspackages. To compare the various packagetypes, the phase current is calculated withthe device nominal current divided by1.414. Because of the high contact areaheating of the contact interface and theterminal itself is much reduced comparedto HiPak or PrimePack modules.Present module designs have rather

high stray inductance values causing highover-voltages. This makes the use ofadvanced fast chipsets – such as the ABB1700V SPT++ chipset – difficult and the

Table 1: Currentdensity of LinPakcompared to othermodule types

Table 2: Current perM8 screw connection

Figure 3: Stray inductance including bus bar LinPak vs HiPak

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use very fast future SiC solutions close toimpossible.The LinPak is designed to offer the

lowest internal stray inductance current

thus enabling low inductive bus bars.Figure 3 compares the LinPak with a HiPakincluding a bus bar and an assumed DC-capacitor inductance of 1.5 nH. Still when

including the bus bar and capacitor, theover-voltage is below critical levelscompared to the HiPak solution – evenwith fast chipsets. This allows for parallel

Figure 4: Doublepulse test setup

Figure 5: LinPak nominal turn-off switching compared to HiPak (top), LinPak and diode SOA at 125°C (bottom)

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connection up to high current applicationswithout compromising the switchinglosses.

Electrical measurements of prototypemodulesPrototype modules with a current rating of2 x 900 A have been tested in a doublepulse test setup at a realistic customer DC-link with laminated bus bars specificallydesigned for the new LinPak (Figure 4).The measurements fully confirmed what

was expected from the LinPak concept.The tests revealed that an overall DC-linkstray inductance including module, bus barand capacitors of about 25 nH can beachieved already with the prototypemodule. As a result, the over-voltage fromthe switching stays well within themaximum device rating and snappy dioderecovery can be considered as a term ofthe past.Figures 5 (top) shows the LinPak and

HiPak IGBT module switching waveformsat nominal conditions. The LinPak showsvery smooth switching characteristics withthree times lower over-voltage and 20 %less switching losses compared to anequivalent HiPak module. The moduleshave also been tested up to the specified

SOA (Safe Operating Area). Thanks to thelow stray inductance no active clamp wasneeded to limit the IGBT over-voltage andboth, IGBT and Diode SOA show veryclean waveforms (bottom).

Conclusions and outlookThe LinPak is a new open standardmodule that satisfies the requirementsposed by both new advanced fast andhigh current density chipsets as well ascustomer wishes for a flexible and scalableIGBT module that is, in addition, ready forfuture technologies such as SiC devices.The benefits of the novel low strayinductance LinPak IGBT module are clearlydemonstrated and measurementsconfirmed the expectations into the newmodule. Today, the benefits of the new package

enable the customer to profit from thelatest chip technologies with lowinductance for achieving the highestcurrent density. Furthermore, particle freeultrasonic welding of the main terminals,advanced wire bonding including the well-established AIN / AlSiC substrate /baseplate material combination for hightemperature cycling capability areincorporated.

Looking ahead, the new module alsoallows a smooth phase-in of futuretechnologies both on chip level withrespect to Silicon and SiC based devices aswell as on advanced material joiningtechniques as they become available forcost efficient mass production withoutmajor changes in the converter design.

LiteratureRaffael Schnell, Munaf Rahimo “The

Quest for Higher Switching Frequencyand its Implications on SemiconductorSwitches” Proc.PCIM’11 Nuremberg,2011Corvasce C., Kopta A., Rahimo M.T.,

Schnell R, Geissmann S., Vobecky J.;“New 1700V SPT+ IGBT and Diode ChipSet with 175°C Operating JunctionTemperature” EPE’2011, BIRMINGHAM,UK, Aug. 2011R. Schnell, U. Schlapbach, K. Haas, G.

Debled, “Parallel Operation of LoPakModules” Proc. PCIM’03 Nuremberg,2003.G. Borghof “Implementation of low

inductive strip line concept forsymmetric switching in a new highpower module”, PCIM’13 Nuremberg,2013

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