THE POTENTIAL AND CHALLENGES OF

CONCURRENT TEST

jean-francois.lescure@teradyne.com

“New Challenges In DFT” – Cambridge, April16th 2015

Because Technology Never Stops

Test Time Reduction

WHAT IS CONCURRENT TEST ?

2

Mu

lti S

ite

SERIALIZED

FLOW

Test

Flo

w

Blo

ck B

Tests

Blo

ck A

Tests

Blo

ck C

Tests

SC

AN

Device trends: Higher complexity Greater integration IP-based architecture

Concurrent Test =

Parallel test of independent device blocks

2-LEVEL

CONCURRENCY

Blo

ck B

Tests

Blo

ck A

Tests

Blo

ck C

Tests

SCA

N

Test

Flo

w

3-LEVEL

CONCURRENCY

Blo

ck B

Tests

Blo

ck A

Tests

Blo

ck C

Tests

SCA

N T

est

Flo

w

Block

A Block

B

Block

C DUT

ATE ARCHITECTURES AND CONCURRENT CAPABILITY

3

MAGNUM

Tester per board • Up to 40 boards • 128 IOs + 16 supplies / board • Controller and patgen / board • External RF instrument

Patgen per board • Up to 16 boards • 128 IOs / board • 2 Patgens per board • Separate analog instruments • Sync. through digital channel

or pattern microcode

J750 + RF tester • Upgrade to any J750 • LitePoint instrument is a full

tester (Src, Cap, processing) • Sync via code or digital

channels

Multi-time domain • Complex SOC tester • Large instrumentation offering • Multiple time domains per

instrument • Multiple flow domains • Protocol-aware engines • Sync-link technology • background DSP • Deferred Limits & Datalog

Complexity & Capability

MOTIVATION FOR CONCURRENT TEST

Reduce test time Objections to this are rare

Situations where increasing parallelism is not an option (questionable ROI, high product mix with little high runners, handler limited …)

Gain is application dependant, typically double digit number

Preserve or adopt an IP-based test strategy As opposed to system-level optimization (reduced pin-count etc…)

Particularly beneficial for SIP

Reduce or optimize investment May appear devious or counter nature

Concurrent test can allow to reduce test time .. or configuration !

As long as a test runs concurrently it doesn’t matter how long it takes (share costly resources)

Improve test Coverage uncommon

CONCURRENT TEST IN THE DEVELOPMENT CYCLE

Capitalize on Cost-of-Test savings asap

Device design enables Concurrent Test

Tester configuration addresses Site Count and

CT flow

Tester SW enables fast CT implementation and

debug

Dev

ice

Vo

lum

e

1st Si Samples

Volume Shipment

Functional Characterization

MultiSite/TTR/CT

Faster Time to Profit

Market pressure

APPRAISING CONCURRENT TEST

Shortest path to FAILURE

CT is a Test Program Optimization

technique

My device already works concurrently

It just takes a “concurrent” tester

It’s trivial

Safest path to SUCCESS

CT is part of my DFT strategy

I need to review the constrains that CT

sets on the device

I need a clear understanding of the

tester architecture and capability

I need to define my concurrent test

strategy early on

Concurrent Implementation

Concurrent Planning

Tester Device

PLANNING PHASE

What tests CAN run concurrently?

• Device conflicts

• Tester configuration

What tests SHOULD be run concurrently?

• Find the optimal concurrent flow

Evaluating manually gets laborious for complex SOC :

• 1000s of tests leads to millions+ combinations

• Satisfying tester rules is getting complex with high levels of concurrency

Need a tool to:

• capture rules

• flag conflicts

• runs scenarios and provides results

Concurrent Test

strategy

Device Architecture

Test System Configuration

& Architecture

Test Time Estimates

CONCURRENT TEST PLANNING PROCESS

Define test blocks

Identify device resources used (by-block)

Identify tester resources required (by-block)

Find valid concurrent flows

Choose and execute *best* option

• Group tests by similar device and tester usage • Typically < ~15-20 blocks

• DUT pins, internal resources, etc. • Will define what concurrency the device can support

• Used to find tester channel assignments that satisfy for the tester rules for a given concurrent flow

• Discard flows with device conflicts • Attempt to find valid concurrent blocks

• Best Cost-of-Test balance of: o tester configuration o site count o Concurrent flow

iterate

CT DESIGN WITH CTEXPERT

Tester Configuration & Usage by Block

Device Requirements & restrictions

Test time estimate Per Block

CONFLICTING BLOCKS

RESULTS FOR ALL SCENARIOS

Optimal CT Flows

DEVICE CONSIDERATIONS

Understand Device Block Independence

access to device block are all signals available shared output pins shared test access pins

access to control registers / data shared interface (JTAG, SPI …) registers separation test mode entry

shared signals / functions reset power supplies test mode entry clock domains

Interference crosstalk noise power consumption power dissipation

scan which in/out pins can cause resource mapping conflict (scan optimization vs

concurrent requirements)

10

Block A Block B

Block C Block D

DUT

Concurrent Test Starts

at the DESIGN STAGE,

requires test eng for

tester capability

discussion

Teradyne Confidential

IMPLEMENTATION PHASE: CHALLENGES

Challenges

Time to Convert

Program to CT

Hard to debug

CT flow complex to

optimize

Identifying the

optimal CT flow

Teradyne Confidential 11

Minimize Development Time Optimize Concurrent Test Efficiency

CTExpert Test Solution Planning

Multi-sheet Support Collaborative development

CTExec Serial / Concurrent Execution

TimeLines

CONCURRENT TEST PROOFS

12 Teradyne Confidential

Device Sites Concurrency

Level TT Savings (%) Comment

Mobile Baseband SiP

Analog

Digital

2 2 41%

DVD device 1 2 33%

Mobile Integrated Cellular RF Tx/Rx

PMIC

ABB

DBB, USB

4 3 25%

Mobile Baseband SiP

ABB

DBB

4 2 6.9%

Device limited

- shared control bus

- unavoidable device

resets

- sensitive tests run serially

CONCLUSION

13

Concurrent testing can be applied to various extents and

various degrees of complexity

Reducing Cost Of Test is the main objective

ATE platforms support Concurrent test in various ways -

each have their specific rules and constrains

Successful implementation of Concurrent Test requires

careful planning and DFT

TO LEARN MORE ABOUT CONCURRENT TEST

Talk to your local Teradyne Representative

(number available on demand)

14