can i correlate my probecard? - swtest.org i correlate my probecard? nasser ali jafari heather...

06/08/99 Ali Jafari/Heather McGill lint Re

Can I Correlate my Probecard? Can I Correlate my Probecard?

Nasser Ali JafariNasser Ali JafariHeather McGillHeather McGill

Intel CorporationIntel CorporationSanta Clara, CASanta Clara, CA

Southwest Test Conference June 8, 1999Southwest Test Conference June 8, 1999


MotivationMotivation❂❂ Pad pitch and pad size arePad pitch and pad size are

getting smaller so must thegetting smaller so must thealignment and planarity specs.alignment and planarity specs.

❂❂ The error budget is small, henceThe error budget is small, hencethe specs are extremely tight.the specs are extremely tight.

❂❂ Miscorrelation between build,Miscorrelation between build,metrology, and sort ismetrology, and sort isconsuming the majority of theconsuming the majority of theerror budget.error budget.


IntroductionIntroduction❂❂ There are several sources of miscorrelationThere are several sources of miscorrelation

that effect the critical parameters within athat effect the critical parameters within aprobecard’s lifetime. Theseprobecard’s lifetime. Thesekey sources of variation are:key sources of variation are:•• PlanarityPlanarity

–– Coplanarity of PlatformsCoplanarity of Platforms–– Motherboard EmulationMotherboard Emulation–– Probecard FlexureProbecard Flexure

•• AlignmentAlignment–– Overdrive and Reference PlaneOverdrive and Reference Plane–– Scrubbing SurfaceScrubbing Surface

(glass vs. sapphire vs. oxidized Al)(glass vs. sapphire vs. oxidized Al)


PlanarityPlanarity

❂❂ Coplanarity of PlatformsCoplanarity of Platforms❂❂ Motherboard EmulationMotherboard Emulation❂❂ Probecard FlexureProbecard Flexure


Coplanarity of PlatformsCoplanarity of Platforms❂❂ Is there a way to achieveIs there a way to achievecoplanarity of platformscoplanarity of platformsbetween build, metrology, andbetween build, metrology, andsort?sort?

❂❂ The majority of planarity error occursThe majority of planarity error occursdue to a lack of coplanarity betweendue to a lack of coplanarity betweenthe probecard and the testingthe probecard and the testingplatformplatform


Varying PlatformsVarying PlatformsSame Probe Card at Various Sites

-10

-5

0

5

10

15

0 200 400 600

Pad Number

Plan

arity

(um

Site #1 with MB #1Site #2 with MB #2Site #3 with MB #3


Same PlatformSame PlatformSame Probecard & Motherboard at Various Sites

-10

-5

0

5

10

15

0 100 200 300 400 500 600

Pad Number

Plan

arity

(um

) Site #1 with MB #4

Site #2 with MB #4

Site #3 with MB #4


Motherboard EmulationMotherboard Emulation❂❂ Can we emulate the environmentCan we emulate the environmentin which probecards are run onin which probecards are run onthe sort floor?the sort floor?

❂❂ There are three key components of There are three key components ofmotherboard emulation to consider:motherboard emulation to consider:•• Pogo pin force on PCBPogo pin force on PCB•• Locking mechanismLocking mechanism•• VacuumVacuum


❂❂ Probecard fixtures for build and metrologyProbecard fixtures for build and metrologyshould emulate the same environment asshould emulate the same environment aswith the test head.with the test head.

❂❂ The inherent nature of the forces caused byThe inherent nature of the forces caused bythings such as vacuum, pogo pins, and thethings such as vacuum, pogo pins, and thelocking mechanism can induce an awkwardlocking mechanism can induce an awkwardreshaping of the probecard.reshaping of the probecard.

❂❂ Proper motherboard emulation is aProper motherboard emulation is aprerequisite for addressing probecardprerequisite for addressing probecardflexure.flexure.

Motherboard EmulationMotherboard Emulation


Probecard FlexureProbecard Flexure❂❂ How accurately do we account forHow accurately do we account forthe flexure in probecard build andthe flexure in probecard build andmetrology testing?metrology testing?

❂❂ With an increasing number of probeWith an increasing number of probeneedles and various interposers (i.e. spider,needles and various interposers (i.e. spider,space transformer) the force applied by thespace transformer) the force applied by theprobecard in the sort environment inducesprobecard in the sort environment inducessome amount of flexure in the probecardsome amount of flexure in the probecardwhich effects planarity results.which effects planarity results.


❂❂ The key places flexure is missed are:The key places flexure is missed are:•• the build process lacks motherboardthe build process lacks motherboard

emulationemulation•• lack of flexure accountability when testinglack of flexure accountability when testing

and repairing a probecard on metrologyand repairing a probecard on metrologytoolstools–– a probe can not accurately be reworked if a probe can not accurately be reworked if

there is no pressure from the entire array onthere is no pressure from the entire array onthe PCB !the PCB !

Probecard FlexureProbecard Flexure


Probecard Flexure ModelProbecard Flexure Model

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Sum of Forces = LockingSum of Forces = LockingMechanism - ReferenceMechanism - ReferenceSurface - Pogo Pins +Surface - Pogo Pins +Vacuum/PCB Resilience -Vacuum/PCB Resilience -PCB&Spider Resilience +PCB&Spider Resilience +Chuck/ProbesChuck/Probes

Chuck/Probes >Chuck/Probes >PCB&Spider ResiliencePCB&Spider Resilience


Probecard Flexure ModelProbecard Flexure Model

Test Head Emulator

Loads

Constraints

Pro/E model

SideView

Pro/Mechanica Analysis of PCB Displacement for a 50lb Load

Mechanical Modeling done by Rahima Mohammed


Planarity with Flexure ModelPlanarity with Flexure Model

SPIDER

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B C

PL (A) = 0PL (B) = 1PL (C) = 2

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SPIDER

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PL (B) = 1 + Fs(A)PL (C) = 2 + Fs(A)

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PL (C) = 2 + Fs(A+B)

Flexure induced by one probe can effect the measured planarity of othersFlexure induced by one probe can effect the measured planarity of others


Possible SolutionsPossible Solutions❂❂ The coplanarity of platforms has to existThe coplanarity of platforms has to exist

in every step, from the probecard buildin every step, from the probecard buildand planarization process to theand planarization process to themetrology test and sort processes.metrology test and sort processes.Since the reference surface of theSince the reference surface of thestiffener ring is the only fixed referencestiffener ring is the only fixed referenceplane, all fixtures need to be coplanar toplane, all fixtures need to be coplanar tothe ring.the ring.

❂❂ Utilization of available metrology tools toUtilization of available metrology tools toplanarize various platforms.planarize various platforms.

❂❂ Add planarity flexure specs to theAdd planarity flexure specs to theprobecard build specificationsprobecard build specifications.


The Effect of Planarity on AlignmentThe Effect of Planarity on Alignment

❂❂ Planarity will AFFECT your alignmentPlanarity will AFFECT your alignmentdata. If we do not correlate planarity wedata. If we do not correlate planarity wewill not have correlated alignmentwill not have correlated alignmentresults.results.


AlignmentAlignment

❂❂ Overdrive andOverdrive andReference PlaneReference Plane

❂❂ ScrubbingScrubbingsurfaces (glasssurfaces (glassvs. sapphire vs.vs. sapphire vs.oxidizedoxidizedaluminum)aluminum)

Trademark of Disney CorporationTrademark of Disney Corporation


Overdrive & Reference PlaneOverdrive & Reference Plane❂❂ What do we use as a referenceWhat do we use as a referenceplane for applying overdrive?plane for applying overdrive?

❂❂ When looking at the lifetime of theWhen looking at the lifetime of theprobecard it has several differentprobecard it has several differentreference planes. With these referencereference planes. With these referenceplanes varying from platform toplanes varying from platform toplatform we can never correlateplatform we can never correlatealignment.alignment.


Overdrive & Reference PlaneOverdrive & Reference Plane❂❂ Techniques for establishing X,Y results vary becauseTechniques for establishing X,Y results vary because

of different reference planesof different reference planes•• Probe Card BuildProbe Card Build

–– Visual specified overtravel applied to glassVisual specified overtravel applied to glass

•• MetrologyMetrology–– First touch of all probesFirst touch of all probes–– Median Signal planeMedian Signal plane

•• ProberProber–– Optical first touch (based on all or a select few probes)Optical first touch (based on all or a select few probes)–– Electrical first touch (based on both signal & bussedElectrical first touch (based on both signal & bussed

probes)probes)–– Electrical median (based on both signal & bussed probes)Electrical median (based on both signal & bussed probes)–– Electrical last touch (based on both signal & bussed probes)Electrical last touch (based on both signal & bussed probes)


Reference Plane MiscorrelationReference Plane Miscorrelation•• We increase our time of tweaking 100X by changing theWe increase our time of tweaking 100X by changing thereference plane from first touch (all probes) to medianreference plane from first touch (all probes) to medianplane (signal probes). If we took 1 minute to tweak a probeplane (signal probes). If we took 1 minute to tweak a probethen our probecard repair time increases from 2 minutes tothen our probecard repair time increases from 2 minutes to3 hours and 20 minutes.3 hours and 20 minutes.•• Can we afford this? Which method actuallyCan we afford this? Which method actuallycorrelates to the prober?correlates to the prober?

# probes tweaked Max scrub Min Scrub

Metrology at median 2 29.3 um 9.1 umMetrology at 1st touch 200 20.7 um 6 um


Alignment at Median SignalAlignment at Median Signal

Median Plane (signal) X,Y Alignment @ OD#1

-20

-10

0

10

20

-20 -10 0 10 20


Alignment at 1st TouchAlignment at 1st Touch

1st Touch X,Y Alignment @ OD#1

-20-15-10-505

101520

-20 -10 0 10 20

9 o’clock9 o’clockpositionposition


Alignment at Various ODAlignment at Various OD1st Touch OD Comparision

OD#1 < OD#2 < OD#3

-20

-10

0

10

20

-20 -10 0 10 20

OD#1OD#2OD#3


Alignment at Various ODAlignment at Various OD

Median Plane OD ComparisionOD#1 < OD#2 < OD#3

-20

-10

0

10

20

-20 -10 0 10 20

OD#1OD#2OD#3

3 o’clock3 o’clockpositionposition


Overdrive & Reference PlaneOverdrive & Reference Plane

❂❂ The reference plane used is a keyThe reference plane used is a keyfactor for alignment datafactor for alignment data

❂❂ Overdrive is also a critical parameterOverdrive is also a critical parameter❂❂ Therefore both the reference planeTherefore both the reference plane

and the overdrive must be controlledand the overdrive must be controlledand correlatedand correlated


Scrubbing SurfaceScrubbing Surface❂❂ Are we accurately able toAre we accurately able tocompare the scrub lengthcompare the scrub lengthof a probecard?of a probecard?

❂❂ There are several factors that vary:There are several factors that vary:•• Different materials (glass, sapphire, oxidizedDifferent materials (glass, sapphire, oxidized

aluminum) - of which each has a different frictionaluminum) - of which each has a different frictioncoefficientcoefficient

•• Various degrees of how much the material deformsVarious degrees of how much the material deformsas it is scrubbedas it is scrubbed

•• Amount of bending of the probe tip due to frictionAmount of bending of the probe tip due to frictionforcesforces


Scrubbing Surface DiagramScrubbing Surface Diagram

Sapphire / Glass(Non-Deforming)

��Aluminum w/ Oxide

(Deforming)


Bending of Probe TipBending of Probe TipCommon bendingcharacteristic of probe tips dueto friction


Possible Solutions - AlignmentPossible Solutions - Alignment❂❂ Set up a structure which will communicateSet up a structure which will communicate

to all processes (build, metrology, and sort)to all processes (build, metrology, and sort)what needs to be done to correlate datawhat needs to be done to correlate data

❂❂ Incorporate modeling to compensate for theIncorporate modeling to compensate for thedifferences in scrub between the variousdifferences in scrub between the varioussurfacessurfaces


Where do we go from here?Where do we go from here?❂❂ Probecard, metrology, and prober suppliersProbecard, metrology, and prober suppliers

need to work with semiconductorneed to work with semiconductormanufacturers to achieve correlation bymanufacturers to achieve correlation bydefining the critical parameters which wedefining the critical parameters which wehave discussed today.have discussed today.

❂❂ Money savedMoney saved•• reduced tweak timereduced tweak time•• minimizing reject ratesminimizing reject rates•• extended lifetime of probecardsextended lifetime of probecards•• reduced chuck force requirementsreduced chuck force requirements


Contact InformationContact Information❂❂ Nasser Ali Jafari - Intel Test ToolingNasser Ali Jafari - Intel Test Tooling

OperationsOperations•• [email protected]@intel.com•• 408/653-7181408/653-7181

❂❂ Heather McGill - Intel Test ToolingHeather McGill - Intel Test ToolingOperationsOperations•• [email protected]@intel.com•• 408/653-7847408/653-7847

can i correlate my probecard? - swtest.org i correlate my probecard? nasser ali jafari heather...

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