- 40 -`

AUGUST08,2012|DATASHEET| Rev3.1

IR3894

12AHighlyIntegratedSupIRBuck

Single‐InputVoltage,SynchronousBuckRegulator

PD‐97745

PCBMETALANDCOMPONENTPLACEMENT

Evaluationshaveshownthatthebestoverall

performanceisachievedusingthesubstrate/PCBlayout

asshowninfollowingfigures.PQFNdevicesshouldbe

placedtoanaccuracyof0.050mmonbothXandYaxes.

Self‐centeringbehaviorishighlydependentonsolders

andprocessesandexperimentsshouldberunto

confirm

thelimitsofself‐centeringonspecificprocesses.

Forfurtherinformation,pleasereferto“SupIRBuck™

Multi‐ChipModule(MCM)PowerQuadFlatNo‐Lead

(PQFN)BoardMountingApplicationNote.”(AN1132)



Figure48:PCBMetalPadSizingandSpacing(alldimensionsinmm)

*ContactInternationalRectifiertoreceiveanelectronicPCBLibraryfileinyourpreferredformat

- 41 -`

AUGUST08,2012|DATASHEET| Rev3.1

IR3894

12AHighlyIntegratedSupIRBuck

Single‐InputVoltage,SynchronousBuckRegulator

PD‐97745

SOLDERRESIST

 IRrecommendsthatthelargerPowerorLand

AreapadsareSolderMaskDefined(SMD.)

ThisallowstheunderlyingCoppertracestobeas

largeaspossible,whichhelpsintermsofcurrent

carryingcapabilityanddevicecoolingcapability.

 WhenusingSMDpads,theunderlyingcopper

tracesshouldbe

atleast0.05mmlarger(oneach

edge)thantheSolderMaskwindow,inorderto

accommodateanylayertolayermisalignment.

(i.e.0.1mminX&Y.)

 However,forthesmallerSignaltypeleadsaround

theedgeofthedevice,IRrecommendsthatthese

areNonSolderMaskDefinedorCopperDefined.

 WhenusingNSMDpads,theSolderResist

WindowshouldbelargerthantheCopperPad

byatleast0.025mmoneachedge,(i.e.0.05mm



inX&Y,)inordertoaccommodateanylayerto

layermisalignment.

 Ensurethatthesolderresistin‐betweenthe

smallersignalleadareasareatleast0.15mm

wide,duetothehighx/yaspectratioofthe

soldermaskstrip.

Figure49:Solderresist

*ContactInternationalRectifiertoreceiveanelectronicPCBLibraryfileinyourpreferredformat

- 42 -`

AUGUST08,2012|DATASHEET| Rev3.1

IR3894

12AHighlyIntegratedSupIRBuck

Single‐InputVoltage,SynchronousBuckRegulator

PD‐97745

STENCILDESIGN

 StencilsforPQFNcanbeusedwiththicknesses

of0.100‐0.250mm(0.004‐0.010").Stencilsthinner

than0.100mmareunsuitablebecausethey

depositinsufficientsolderpastetomakegood

solderjointswiththegroundpad;highreductions

sometimescreatesimilarproblems.Stencilsin

therangeof0.125mm‐0.200mm(0.005‐0.008"),

with

suitablereductions,givethebestresults.

 Evaluationshaveshownthatthebestoverall

performanceisachievedusingthestencildesign

showninfollowingfigure.Thisdesignisfor

astencilthicknessof0.127mm(0.005").

Thereductionshouldbeadjustedforstencils

ofotherthicknesses.



Figure50:StencilPadSpacing(alldimensionsin mm)

*ContactInternationalRectifiertoreceiveanelectronicPCBLibraryfileinyourpreferredformat

Part #	ERJ-3EKF1000V
Description	RES THKFLM 0603 100 OHM 1% 1/10W 100PPM/ C SMD - Cut TR (S
Category	CHIP RESISTOR
Availability	Out of Stock
Qty	0

ERJ-3EKF1000V

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