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What are Adhesion and Peel-off?

 

A pressure-sensitive adhesive (PSA) tape is used in various fields because it can be applied instantaneously with rather weak pressure and it is easy to remove.
Specifically, in various forefront industries, such as in the fabrication of liquid crystal panels, semiconductors, optical instruments, solar batteries, and in medical treatment, the automobile industry, architecture, and IT, the unique capability of PSA is applied to the production process as well as constitutive parts in devices.

 

PSA tape is valued at the three basic elements, the so-called tack test, its adhesion, and its shear holding power. In general, the purpose of the peel-off test is to measure adhesion forces quantitatively at 90° and 180° angles in response to JIS Z0237:2009.

 

 At the angle of 180°, the result of the peel-off test is influenced by the thickness and degree of elasticity degree of the PSA tape. At an angle of 90°, the result of the peel-off test is less influenced by these characteristics of the tape and is more reliable and consistent for the evaluation of adhesion and cohesion. However, the test result is unsatisfactory at the present due to the deviation from a 90 °angle arising from the sagging and elongation of the tape.
   

A peel-off analyzer of any angles is already available on the market. To maintain the peel-off angle constant, linear movement of a substrate and a tilted detector element are utilized by simply satisfying the geometrical condition as shown in Fig. 1. The angle of peel-off is shown by the following formula;  θ=180−2α

  

The distance of peel-off method-2.jpgis equal to the distance of method-3.jpgbut the stage of substrate moves horizontally from  A  to A’ indicated as method-4.jpgin Fig. 1.
The relational calculus is expressed as the following formula,

 

            method-5.jpg

where Lp is the velocity of the stage movement.

 adhesion_img01.JPG
Fig.1 The principle of the conventional peel-off method
 

The Flat Plate Cross Stage Method was invented by Kyowa Interface Science Co., Ltd.
The synchronized actuator mechanism is designed to realize high accuracy evaluation of flat plate sliding at specified crossed angles with the pulling direction on a stage.
Refer to Fig.2, a flat cross stage shifts in the direction of A while a stage moves toward the direction of B at the same distance and speed.

 

  adhesion_img02.JPG

 

Fig.2 The principle of the Flat Cross Stage method
 
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