Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Reexamination Certificate
2000-06-06
2001-11-13
Raevis, Robert (Department: 2856)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
Reexamination Certificate
active
06314819
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display method, a container, a carrying document, an adhesion strength measuring method, and a composite manufacturing method for resin material (resin composition), and more particularly to a display method, a container, a carrying document, an adhesion strength measuring method and a composite manufacturing method for resin material (resin composition) which is capable of providing a universal adhesion strength regardless of dimensions and configuration of adhering specimens, and further to a resin material (resin composition), the adhering reliability of which can be easily evaluated.
2. Description of the Related Art
In resin-molded electronic and electric parts containing inserting components such as resin encapsulated semiconductor devices and resin insulating transformers, the inter-faces between the resin and the inserting components are subjected to high residual stress due to cure shrinkage of the resin and thermal expansion mismatch between the resin and the inserting components.
Further, the internal exothermic action and the harsh heating/cooling operations increase the thermal stress which sometimes causes delamination during operations of the components and reliability tests.
Such a delamination at adhering interfaces not only results in corrosion of electric wiring materials and electric insulating degradation, but also causes a variety of other damages, such as cracking of the resin and wire breaking due to the stress concentration by the delamination.
The evaluation of resin material adhesion strength is therefore a critical issue in assuring the reliability of such resin-molded components.
Conventional methods for measuring the adhesion strength of resin material apply tensile or shear loads to an adhering specimen, and then divide the obtained fracture (delamination) loads by the adhesion area or length as described in IEEE Transactions on Comp., Hybrids, Manuf. Technol., Vol. 14, No. 4 (1991) pp. 809-817 and in Adhesion Technology, Vol. 9, No. 1 (1990) pp. 60-63 and 64-75.
Another method is disclosed in the Proceedings of the 67th Spring Annual Meeting of the Japan Society of Mechanical Engineers Ser. A (1990), pp. 75-77. In this method, a load is applied to an adhering specimen having partly formed delaminating portions, and a stress distribution near the delamination tip, i.e. near the boundary between the delaminating portion and the adhering portion, at the onset of delamination propagation is described by fracture mechanics parameter.
Further, other method is disclosed in the Transactions of the Japan Society of Mechanical Engineers, Ser. A, Vol. 54, No. 499 (1988) pp. 597-603. In this method, a temperature at which delamination takes place due to a residual stress is measured during cooling process after molding an adhering specimen, and a residual stress distribution at the delamination onset portion at that time is analyzed.
Among aforementioned conventional arts, in the tensile/shear loads applying method there is present the residual stress already when the adhering specimen is made. Therefore, the measurable adhesion strength would be nothing more than an apparent adhesion strength, which is a superimposition of the residual stress on the true adhesion strength.
Particularly in the case of semiconductor transfer molding resin for semiconductor encapsulation, the adhesion strength is relatively low due to a mold release agent contained in the resin material for easily parting from molding die. As a result, the reduction rate of the adhesion strength caused by the residual stress becomes large, such that the residual stress sometimes causes by itself the delamination at the interface.
Even if the adhesion strength measured by such a method is compared to an interface stress obtained by analysis or experiment, the adhering reliability of the resin molded components cannot be evaluated.
Further, the stress at the adhering interface is not uniform, but has singularity so as to become infinite at the end portions.
All the distributions of the residual stress and the stress caused by the load application during the adhesion test depend on the dimensions, shapes and materials of the specimens. Accordingly, in such conventional methods, as dividing the load by the adhering area on the assumption that the stress is uniformly distributed, dividing the load by the adhering length on the assumption that the load acts only on a line along the delamination front, the resulting adhesion strength depends on the dimensions, shapes etc. of the specimens, such that no universal measured value can be obtained.
If there is no residual stress, it is possible to obtain a universal adhesion strength by a method of describing a stress distribution near a singular point such as delamination tip by use of fracture mechanics parameters. On the other hand, however, in the case of the residual stress being present, the residual stress distribution must be obtained by analysis, as in the aforementioned last reference, the Transactions of the Japan Society of Mechanical Engineers, Ser. A, Vol. 54, No. 499 (1988) pp. 597-603. The analysis of the residual stress would be sometimes quite complicated or difficult to be performed with high accuracy due to conspicuous temperature dependency of the material properties or significant viscoelastic behavior at high temperatures depending on the materials of the resin composition.
Further, as in the case of the last reference, if the delamination is caused only by the residual stress, there would be a disadvantage that the adhesion strength may not be freely measured at any desired temperatures.
Thus, in the conventional methods, any universal adhesion strength as material property values could not be actually obtained. As a result, it is not possible to quantitatively predict the adhesion reliability of the interface of resin-molded products, such that the adhering state and adhesion strength etc. of the interface should be actually tested and measured by actually making the resin-molded products.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method for measuring adhesion strength of resin material which is capable of separating a true adhesion strength from a residual stress and of accurately and readily measuring a universal strength independent of dimensions and shapes of specimens, and to provide a display method, a container and a carrying document of the resin material, using the measured result and a manufacturing method of a composite body using the measured result.
It is another object of this invention to provide a resin material the adhesion reliability of which at its product interface can be readily predicted and evaluated from given material property values.
The first object can be attained by: making an adhering specimen having a partial delaminating portion between a resin material and an adherend requiring the adhesion strength and having a configuration as residual stress on the adhering interface near the delamination tip is dominated by shear stress component; applying loads such that two types of shear stress in the positive and negative directions are generated on the interface near the delamination tip; and obtaining apparent delamination propagating strengths in respective directions.
The second object can be attained by attaching the measured result of the adhesion strength obtained by the afore-mentioned means to the resin material.
The display method, the container and the carrying document for the resin material according to this invention feature to describe an adhesion strength based on shear stress of a resin against an adherend material together with the name of the adherend material, or to describe an adhesion strength of the resin against the adherend material by substantially excluding influences of residual stress.
In this case, the term “resin material” represents a resin material before being molded, and particularly in thermosetting resin it signifies a resin compositi
Hirose Isao
Nishimura Asao
Tanaka Naotaka
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Raevis Robert
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