Copper pillar testing

19 December 2014

Copper pillar
Copper pillar
  • Shear and/or pull testing
  • Sensor accuracy ±0.075%

Friction grip
Friction grip


Copper Pillar is rapidly being adopted as a bumped wafer interconnect. The construction is that of a Copper cylinder around 50µm in diameter and height, topped with a dome of solder.

Reformed solder ball
Reformed solder ball

As with any interconnect the quality of the bonding process between the different parts is vital for the reliability of the finished product. The bond between the copper and its pad on the wafer are of particular interest as this is seen as the most likely failure mode. In a bond test a failure mode between the copper and wafer is then the “Failure mode of interest”.

Pull test copper pillar gripped with two tapered cavities
Pull test copper pillar gripped with two tapered cavities

Pull testing

This failure mode can be produced by either a pull or a shear test and the measured bond strength used for your process control. In many other applications pull testing is typically preferred because the bond is subjected to a simple tensile load, distributed over the bond area. The bond separation is clean making failure mode analysis of the surfaces relatively easy. Unlike solder bumps, Copper is relatively hard and gripping it therefore easier.

Example of typical pull test results for Copper pillar
Example of typical pull test results for Copper pillar

Solder balls require precise reforming in order to be able to apply a meaningful test load on to the bond. Copper also has to be reformed in order to be able to grip it but this takes the form of well know gripping methods such as plain surfaces and friction, a few serrations that slightly reform the copper in order to get a mechanical grip or a slight tapper.

Failure mode P1
Failure mode P1

Shear testing

An alternative to pull testing is a shear test. If this is done with a very low shear height the bond is subjected to mostly shear. If a high shear height is used the bond is loaded by shear and a bending moment. It is though the bending loads, and in particular the tension side of the bending moment, that typically cause the bond to fail. The pillar tends to pivot on its edge furthest from the shear tool, making the failure mode very similar to that of a pull test.

Copper pillar low shear height and bond fails in shear
Copper pillar low shear height and bond fails in shear

The advantages of a high shear test are that the tool and test are much simpler. Making pull tweezers with 50µm cavities is difficult and costly. Aligning them to the pillar takes time and requires skill. A shear test is no different to that commonly used when testing wire bonds. The only difference being the shear height is bigger. The tools cost a lot less and its alignment to the pillar is not so critical, making it less skilled and faster.

Copper pillar high shear height and bond fails in tension
Copper pillar high shear height and bond fails in tension

Variations in shear height will cause variations in the test result but with the Condor Sigma accuracy of ±1µm these affects are likely to be less than those caused by the grip reforming and operator misalignment in a pull test. It is though beneficial to test with the highest possible shear height as this reduces any effect from the small variations in height and assures that the bending moment dominates the failure mode.

Example of typical shear test results for Copper pillar
Example of typical shear test results for Copper pillar

For a solder ball a Cold Bump Pull test is known to be better than shear. A 1st bond Gold ball test is best done with a low shear height. The reason for both of these comes from our “Golden rules of bond testing” ©, they both produce the highest number of failure modes of interest or the highest possible test force.

Failure mode S1
Failure mode S1

In the case of Copper pillars we should be guided by these same rules. Shear is the simplest test and it does produce the failure mode of interest. The optimum shear height will be the one that maximises this or produces the highest test force.

Choose between pull and shear testing

The choice between pull or shear testing depends on the application and the test objectives. If you are interested to find out more please contact us for more information, to request a demonstration or a quotation.


Dec 2019 Xyztec faces any challenge
Jul 2019 Meet the world’s biggest bond testers
Apr 2019 Free SMTconnect ticket? Register now
Aug 2018 Is Fully Automatic Bond Testing Possible?
Jul 2017 Advances in Thin, 3D and MEMS Die Bond Strength Testing
May 2017 Shear testing copper pillar
Mar 2017 Fracture strength of thin wafers and die
Feb 2017 Centralized database for enhanced security and SPC options
Jan 2017 Full Automation with Improved Pattern Recognition, Fiducial Marks Analysis, Wire Detect and Failure Mode Analysis
Dec 2016 Coating and film testing
Nov 2016 Latest software release enables automatic grading
Oct 2016 Vision enhanced materials testing

Click to subscribe.

Other news

02 Mar EPIC invests in XYZTEC’s most advanced bond tester
17 Jan Visit us in Tokyo this month
13 Nov Visit us at Productronica in München
03 Oct Xyztec at EuWoRel Berlin
18 Sep Sigma and Magazine Loader in action at Semicon Taiwan
17 Sep Xyztec at EMPC conference in Pisa
04 Sep Meet us worldwide in September
05 Jul Teaming up with Micronnect B.V. and BRIDGE S.r.l.
07 May Newest Sigma HF High Force bond tester live in action at SMTconnect
26 Apr XYZTEC spreads bond testing knowledge to partners worldwide
20 Mar Visit us at Semicon China
29 Jan XYZTEC at Semicon Korea
21 Nov Presentation at CSPT 2018
15 Nov Matelec show 2018 for the Electrical and Electronics Industry with Antycip
20 Sep Successful ESTC Conference in Dresden, Germany
11 Jul LEGO® for Nepal sponsored by XYZTEC
05 Jun Visit us at SMT Hybrid Packaging Nuremberg
20 Apr Smart LED and Solar panels for XYZTEC head office
18 Apr XYZTEC workshop at IMAPS UK
16 Mar ODEOM shows Condor Sigma in Istanbul
15 Mar Semicon China under way
31 Jan Condor Sigma W12 at Semicon Korea
04 Dec Condor Sigma stars in Audi Tech Day video
10 Nov Raysun to represent XYZTEC in China
23 Oct Award for First Technology China

View all news

Subscribe to our RSS-feed to be notified of the latest news automatically. You can also find us on Facebook, LinkedIn, Twitter, Weibo 微博, Google+, YouKu 优酷 and YouTube.

XYZTEC Newsletter


Your name:

Your email:

© 1999-2016 XYZTEC BV Disclaimer, Privacy, Cookies
Condor Sigma
Condor 150HF
Test types
Markets & solutions
Sales & support

XYZTEC Netherlands

J.F. Kennedylaan 14-B
5981 XC Panningen
Netherlands (map / route)

Tel: +31-77-3060920
Fax: +31-77-3060919

Find your local representative

XYZTEC Germany

Schäferei 18
06237 Leuna
OT Günthersdorf
(map / route)
Tel: +49-34638-666690
Fax: +49-34638-666695
Cell: +49-152-21722629
Email: Volker Loibl

Find other office locations

XYZTEC New Hampshire

33 South Main Street Unit #1,
Wolfeboro, NH 03894
(map / route)
Tel: +1-978-880-2598

Find other office locations

Technology leader in bond testing worldwide