Copper has become an accepted replacement for gold when it comes to interconnect material for stud bumps, wire bonds and pillars. Copper has many advantages such as better electrical and thermal conductivity, cost reduction and less intermetallic growths.
A crucial aspect of the quality assurance method during manufacture is analyzing the mechanical integrity of these bonds. However, testing copper interconnects poses many challenges for conventional shear analysis. Nordson DAGE has developed the first bond ball pull (FBBP) test technique to meet these challenges.
The ball bond is held with the aid of a specialized tweezer jaw such that a vertical load is applied to the bond thereby enabling a pull test to be performed.
The copper’s stiffness enables tensile testing to be conducted thus the FBBP test technique can be applied to various types of interconnects such as stud bumps, ball bonds and pillars.
Micro jaws are constructed to tightly hold the bumps, and vertical loads are enforced with the suitable load cartridge. Regular failure forces are measured and reproducible failure modes are monitored.
Key Features and Benefits
The main features and benefits are listed below:
- Low force load cell and jaws enable analysis of emerging interconnect tools such as stud bumps and copper ball bonds
- Copper bonds as small as 50µm in diameter can be analyzed
- Setting up and performing the test is quick
- Pad cratering artifacts, produced by shear tests, can be avoided in pull testing
Conducting the Test
Nordson DAGE tools enable performing copper interconnect tensile tests easy. Nordson DAGE’s experienced design engineers will help customers to assess the specific geometry of the interconnects to be tested. The assessment will take into consideration important factors such as shape, height, diameter and pitch so as to decide whether the testing can be carried out in a precise manner. A software controlled air-driven collet mechanism enables the opening and closing of the jaws, and this ensures adjusting the clamping pressure of the jaw with very high precision through incremental increases in the air pressure until the interconnect fails on test activation.
The advantage of closing the jaws on the copper interconnect will not reform it as the load is applied via a friction fit of the jaws unlike in the case of cold bump pull on traditional solder balls. When the pull system is well formed, the alignment process is easier to handle, thereby ensuring stable outcome without the requirement of an operator.
Figure 1. First bond ball pull test.
Precise dimensions of the interconnect are needed for the specialized jaw design. Nordson DAGE provides the additional tools to ensure that copper interconnect tensile tests can be conducted easily. The company provides complete technical support worldwide.
About Nordson DAGE
Dage was founded in 1961 and is a market leader in its chosen markets of Semiconductor and PCBA Manufacture. It has an award winning portfolio of Bondtester and X-ray Inspection Systems for destructive and non-destructive mechanical testing and inspection of electronic components.
Dage was acquired by the Nordson Corporation in 2006.
Nordson DAGE has a strong portfolio of award winning products for destructive and non-destructive mechanical testing and inspection of electronic components. It has an excellent, wholly owned distribution and support network of seven offices covering Europe, Japan, China, Singapore, and the USA, and maintains representative offices in other territories.
With its self-contained R&D facilities, Nordson DAGE has developed world-leading products for testing wire bonds on semiconductor packages such as BGA, Chip Scale Packages (CSP) and other electronic components. More recently Nordson DAGE has been heavily involved in the testing of the newest technology 300 mm wafer bump shear.
Nordson DAGE has developed an excellent suite of award-winning X-ray inspection equipment targeted at both the Semiconductor and PCBA markets.
Control of the patented core technology of X-ray tube manufacture ensures that the high-resolution X- ray will detect, identify and measure even the smallest of features. Nordson DAGE's high precision, state-of-the-art inspection equipment when joined with their sophisticated software offerings, ensure that the equipment is simple to use.
Our core strategy:
- To support our customers wherever they do business,
- To continually develop new products that provide its customers with enhanced competitive advantages,
- To develop products which bring new advantages to its customer base
- To control the core technologies that underpin its products.
This information has been sourced, reviewed and adapted from materials provided by Nordson DAGE.
For more information on this source, please visit Nordson DAGE.