A study of micro-holing of brittle materials using micro-abrasive jet machining
Date Issued
2005
Date
2005
Author(s)
Chen, Li-Chun
DOI
zh-TW
Abstract
Abstract
In the process of powder blasting, mask was closely stuck on the substrate to protect the area of substrate not to be powder blasted. The quality characteristics of this process depend completely on the erosion resistance of mask to the powder blasting and the accuracy of mask opening size. this paper will provides a new idea and methods to improve the precision and achieve a good quality of this process.
Instead of one protective layer for mask that is conventionally used, two layers are coated on the surface of the substrate material. The inner layer is water-soluble resin with excellent adhesion to the substrate but having weak resistance to powder erosion, and the second layer is a photosensitive oligomer that is adhered well to the first layer and has very high resistance to powder erosion. Once the openings of the second layer are formed at the desired positions via a photo-etching method, a printing method, or other methods, the holes or grooves can be obtained by etching through the openings of the second layer to the first layer and the substrate by a powder blasting process. Then the whole protective coating is easily and smoothly stripped off without any damage to the substrate by dissolving the first layer with water. Such a protective coating possesses two contrary characteristics: high resistance to powder blasting and easy removal from substrate after powder erosion. Due to two layers are coated on the surface of the substrate material, the material of each layer can thus separately be developed to its utmost properties by researcher, and therefore, more space is created for developing in the powder blasting process.
In creating a hole on brittle materials by double-side sand blasting, the rebounding sand particle flux during the process may result in underetching at the edge of the mask opening, and leads to a larger sized fluid hole than desired one. In practice, determination of the correct mask opening size was made mainly by trial and error or with fine-tuning of the masking process and compensation for mask wear. In this paper, relationships between the mask opening size and desired size of a hole on both the front and the back sides of the substrate are derived. For the front side, by taking into account the underetching effect, an equation is derived based on kinetic energy theory. For the back side, there is negligible rebounding sand particles, and the mask opening size is set to be equal to the desired size of the hole. Experiments were conducted to verify the derived relationships. It is found that the measured sizes of the eroded holes on both the front and the back sides of the wafer substrate are distributed normally. The desired hole sizes deviate slightly from the median of a normal distribution curve, and the maximum predicted errors are 2.4% and 3.0% for front side and the back side sand blasting, respectively. The very satisfactory result of the predicted errors for various hole size shows that the derived relationships is applicable for determination of mask opening size in powder blasting process.
With this improvement of hole accuracy in size, it is expected that the powder blasting process will provide another choice for the process of machining holes on brittle materials.
Subjects
脆性材料
噴蝕
護膜樣孔尺寸
過切噴蝕
brittle materials
sand blasting
mask opening size
underetching
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-94-D87522016-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):15de46813b4be94ab431d210a9b428b3