Silicon wafer bending strength testing

Recently, Andy Li received silicon wafer samples from customers and needed to test their bending strength. To meet the customer’s testing needs, the VTS measurement and control technical team developed a set of technical solutions for it. This included both testing equipment and methods.

Silicon wafer bending strength testing Test Principle

The principle of the silicon wafer bending strength test is to apply a gradually increasing bending load to the sample. By doing so, we can determine the maximum bending stress it can withstand before breaking. Consequently, this process allows us to evaluate the material’s fracture resistance and structural stability.

Test related standards

Tests were conducted based on the reference standard GB/T 15615-1995 “Test method for bending strength of silicon wafers”

Testing equipment

1. VTS – WDW- 5KN universal material testing machine

2. Protective cover

Since the silicon wafer will break due to stress during the test and produce flying fragments, the protective cover can effectively isolate these fragments to prevent harm to personnel.

3. 3-point bend test

4. Thickness gauge

5. Test conditions

Sample name: silicon wafer

Test temperature: room temperature

Test type: three-point bending

Test speed: 0.508mm/min

IV. Test process

Sample preparation

Before the experiment begins, cut the silicon wafer into a shape that meets the test requirements, clean and dry it, and ensure that there is no contaminant on the surface of the sample to obtain accurate test results.

Measure the thickness and width of the sample

Use a thickness gauge with an accuracy of 1 micron to measure the thickness and width of each sample silicon wafer to ensure data consistency.

Thickness measurement: Measure the thickness of the silicon wafer, with an average value of 0.775mm.

Length measurement: Measure the length of the silicon wafer, with an average value of 40mm.

Width measurement: Measure the width of the silicon wafer, with an average value of 20mm.

Equipment and fixture preparation

Firstly, install the test equipment by using the VTS-WDW-5 universal material testing machine. Additionally, install a protective cover to ensure safe operation. The protective cover can effectively isolate the fragments splashed by the fracture during the test, thereby avoiding harm to personnel.

Next, install the three-point bending fixture on the test machine. Ensure that the fixture position is accurate and meets the requirements of the silicon wafer bending test.

Test condition setting

Set the test machine parameters and test according to the following conditions:

Sample name: silicon wafer

Test temperature: room temperature

Test type: three-point bending

Test speed: 0.508mm/min

Start the experiment

Place the silicon wafer sample on the three-point bending fixture, start the test machine to apply bending force at a preset speed, and record the bending strength data of the silicon wafer.

Data recording and analysis

Firstly, record the maximum bending stress and related data that the silicon wafer withstands before breaking. Subsequently, organize and analyze this data. Finally, evaluate the bending strength performance of the silicon wafer material.