Adhesives are innovative products that are used to join components together and help in resisting separation.
To this end, a wide range of techniques are available to assess the quality of the bond created. In case the adherents are flexible, different types of peel tests are performed. For instance, a ‘T’ peel test can be employed if both adherents are flexible, and a 90° peel test can be used when one of the adherents is stiff.
In order to sustain the angle, the adherent which is rigid is positioned on a sliding stage which shifts as and when the tape is pulled. In case of small materials, where only a small amount of peel force is required, friction may lead to major errors and hence an alternative technique is needed for this kind of measurement.
4000Plus Micro Test System
This issue can be overcome by using the 4000Plus micro test solution equipped with Paragon™ software. This system uses active stage control to sustain the peel angle and includes a variety of low force cartridges to evaluate the peel strength of micro samples such as PCB copper tracks. In this method, ribbons, tapes and tracks are firmly held using air actuated tweezers that operate together with the load cartridges.
The 4000Plus system provides the required measurement capability, enabling the basic measurement of the force needed to peel a film. The system also provides a complete understanding of the characteristics of the adhesive layer.
Integrated Software and Accessories
With the help of multi-axis stages as well as the assorted range of dedicated load cells, the 4000Plus system can be sued for peel testing. These load cells are capable of measuring from less than 1g to up to 100kg. In addition, the integrated Paragon™ software allows for rapid set up of test parameters and helps obtain force-displacement information. Peel rates ranging from microns to 5mm/s can be set. This helps in studying the time-dependent properties of the adhesive.
Moreover, test data can be sent to different formats for complete analysis through third party packages. A series of work holders including a heated stage are also available. These accessories allow tests to be carried out at up to 400°C.
Figure 1. Shear test at elevated temperature.
Peel testing provides just a single measurement of adhesion. In case both adherents are stiff, shear testing (Figure 1) offers a simple and flexible method to determine bond strength.
On the other hand, a stud can be fixed to the sample and utilized to apply tensile loading to the bonded component. A variation of the stud pull method is the Hot Probe Attach (HPA) where a pin is automatically attached to one of the adherents and then the tensile load is applied on the pin.
The traditional peel test determines the force per unit tape width in order to remove the tape from a stiff adherent (Figure 2).
This test is often employed to perform comparative measurements. For example, adhesives of different types can be compared depending on their ability to join a tape and substrate. Given the fact that results depend on the mechanical characteristics of the tape as well as on the thickness of the glue layer, it is important to fix these parameters to obtain reliable data.
Figure 2. Force per unit width versus distance peeled for five samples of an adhesive tape of the same batch.
The properties of adhesives are significantly affected by temperature, peel rates, and environmental conditions. The peel test can be easily performed with the sample immersed water. This would help in assessing the effect of ingress, if any.
The shear test technique determines the peak force needed to isolate two rigid surfaces attached together. Self aligning technology together with a variety of tools ranging from 25µm face width to a few centimeters allows force to be evenly applied to a wide range of samples.
It is also possible to achieve micron level precision of shear heights, thanks to the surface detection capabilities of the shear cartridge. In case of metallic surfaces that are difficult to hold, HPA provides a suitable method of bonding and allows cyclic or static forces to be applied.
Thus, Nordson DAGE’s 4000Plus micro test system with integrated Paragon™ software can be effectively used for performing micro adhesion tests.
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.
This information has been sourced, reviewed and adapted from materials provided by Nordson DAGE.
For more information on this source, please visit Nordson DAGE.