Bead Probe Designation Technology (AMBPT)

Agilent Medalist Bead Probe TechnologyCustomer Viewable

May 2007

Agilent Medalist Bead Probe

Technology (AMBPT)

Name

Designation


May 2007

Presentation OutlineWhat will we see today?

- In-Circuit Access and Industry Challenges

- Solution: Agilent Medalist Bead Probe Technology (AMBPT)

- Using AMBPT

- Questions


May 2007

In-Circuit AccessWhat’s the Problem ?

No layout space for targets

– Board density increasing rapidly

• More devices, smaller devices, with more device pins – more densely packed

• Finer trace-space routing – tighter routing restrictions

Targets affect board performance at higher frequencies

– Targets are 3 to 6 times wider than traces (e.g., 30 mil target on 5 mil

trace)

• Big targets present a lumped capacitance to ground somewhere mid-trace

• Lumped capacitance creates an impedance mismatch – causes reflections


May 2007

In-Circuit AccessWhat’s the Problem ?

Board designer perceives unacceptable schedule and performance risks due to “non-value-added” test requirements

– Adding test points disturbs the “best” layout, may hurt performance

– Takes time and skill to do, yet can’t do all that are requested

– Causes friction between Design and Test Departments

No test points, ideal layout

IC 1 IC 2

Two added test points

IC 1 IC 2


May 2007

Solution: Agilent Medalist Bead Probe TechnologyA New Way of Looking at Access

New Way (Close Up):

• Place target in the Fixture

• Hit it with a pointed probe

on the Board

Old Way (Close Up):

• Place target on the Board

• Hit it with a pointed probe

in the Fixture

Fixture

TargetProbe

Board

Fixture

Target Probe

Board


May 2007

Solution: Agilent Medalist Bead Probe Technology


May 2007

Solution: Agilent Medalist Bead Probe TechnologySectional views

Bead

FR4

Trace MaskSolder

EndSection

Bead

FR4

SideSection

Trace


May 2007

Solution: Agilent Medalist Bead Probe TechnologyBead Contact with Target

FR4

EndSection

Bead Flattened


May 2007

Wiping Action of Test Probes

- Pointing error inherent to test probes

- As the plunger draws back to the barrel, the tip of probe swings back and forth a few times.

- This creates “wiping action”

- Provide good contact after initial deformation


May 2007

Solution: Agilent Medalist Bead Probe TechnologyBead probes take on the width of the underlying trace and therefore provide “Layout Independent Test Points”.We don’t have to change the layout to get test access !


May 2007

Solution: Agilent Medalist Bead Probe TechnologyBead probes, compared to standard test pads have virtually no performance impact.

Source: “A New Probing Technique for High-Speed/High-Density Printed Circuit Boards”, K. P. Parker, International Test Conference, paper 13.1, Oct 2004, Charlotte NC, reprinted with permission.

30 80 130 180 230 280 330 380-20 420

0.0

0.4

0.8

1.2

1.6

2.0

2.4

-0.4

2.8

time, psec

p_

idea

l_5_

3_0

Voltag

e

30 80 130 180 230 280 330 380-20 420

0.0

0.4

0.8

1.2

1.6

2.0

2.4

-0.4

2.8

time, psecp_

ST

D_5_3_

0V

oltag

e

Ideal Trace Trace with 35 mil test target


May 2007

Solution: Agilent Medalist Bead Probe TechnologyBead probes, compared to standard test pads have virtually no performance impact.

Source: “A New Probing Technique for High-Speed/High-Density Printed Circuit Boards”, K. P. Parker, International Test Conference, paper 13.1, Oct 2004, Charlotte NC, reprinted with permission.

30 80 130 180 230 280 330 380-20 420

0.0

0.4

0.8

1.2

1.6

2.0

2.4

-0.4

2.8

time, psec

p_

idea

l_5_

3_0

Voltag

e

Ideal Trace Trace with 9 bead probes

30 80 130 180 230 280 330 380-20 420

0.0

0.4

0.8

1.2

1.6

2.0

2.4

-0.4

2.8

time, psecP

_B

EA

D_5_

3_9

Voltag

e


May 2007

Solution: Agilent Medalist Bead Probe TechnologyBead probes also have superb high-frequency performance. The board’s normal performance is completely unaffected by their presence.

SIC (Centered) 1, 2 , 3 with and without Bumps

-8

-7

-6

-5

-4

-3

-2

-1

0

0.0E+00 5.0E+09 1.0E+10 1.5E+10 2.0E+10

Freq

dB

SIC1 SIC2 SIC3 SIC1_B SIC2_B SIC3_B

Source: “Implementation of Solder-bead Probing in High Volume Manufacturing”, M. Doraiswamy and J. J. Grealish, International Test Conference, paper 5.4, Oct 2006, Santa Clara CA, reprinted with permission.

Note, some traces had as many as 30 beads.


May 2007

Solution: Agilent Medalist Bead Probe TechnologyHow are bead probes made? (The short story)

Bead Probes are created using standard solder paste/reflow technology

– No new processing steps are required

– No unusual masking, stenciling or soldering parameters are required

There are two, similar types of Bead Probes

– Soldermask-defined Beads (on planar copper)

– Metal-defined Beads (on signal traces)

Manufactured the same way

– Open a hole in the soldermask over desired Bead location

– Apply paste with a stencil aperture (same step as all other paste applied)

– Reflow (same process as all other paste is reflowed)


May 2007

Solution: Agilent Medalist Bead Probe TechnologyHow are Bead Probes made? (The short story)

Cu Trace

Cu Trace

Stackup

Solder Mask Opening Solder Stencil Opening

Stackup

W

L

D


May 2007

Solution: Agilent Medalist Bead Probe TechnologyHow are bead probes made? (The short story)After stenciling, a paste brick remains that flows into a bead upon heating.


May 2007

Video Animation of Bead Probe Fabrication

Run video to show Bead Probe Fabrication


May 2007

THE

IMPLICATIONS

ItItItIt’’’’s proven. s proven. s proven. s proven. ItItItIt’’’’s been done ...s been done ...s been done ...s been done ...Just got to do it the right way.Just got to do it the right way.Just got to do it the right way.Just got to do it the right way.


May 2007

Fixture vendors

Headless probes

Spring force as per recommendation


May 2007

Contract Manufacturers

Solder paste mix

Stencil aperture sizing

Reflow

Rework steps


May 2007

Probe Makers

Flat-face headless probes


May 2007

CAD Engineers

Solder mask opening

Test attributes


May 2007

Expanding coverage opens doors

VTEP

iVTEP

NPM


May 2007

Agilent Intellectual Property

- 16 patents and patents-pending

- Filed in the USA and other countries


May 2007

Licensing

Types of licenses :

• Customer license

• Equipment license

(for test equipment vendors)


May 2007

Process for obtaining a Customer License

• Go to www.agilent.com/see/beadprobe

• Complete the licensing web-form

• A copy of the license agreement will be made

available to you

• You will be contacted by Agilent

• Return the signed agreement to Agilent

• Agilent counter-signs and returns the agreement

plus the Bead Probe Handbook


May 2007

AMBPT wins prestigious EDN Innovation Award of the Year (2007) EM Asia Innovation Award 2007

- Based on product released in 2006. (AMBPT was launched Nov 2006)

- Results and ceremony on 3rd April 07.

- Agilent Medalist Bead Probe announced as Innovation of the Year

- Dr Ken Parker named as one of the finalist for Innovator of the Year

- http://www.edn.com/index.asp?layout=InnovationAwardComp&year=2006&order=55


May 2007

Thank You !

Questions ?

See also:

www.agilent.com/see/beadprobe

Bead Probe Designation Technology (AMBPT)

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