What Is a Pressure Cooker?
Pressure cookers are used to evaluate the humidity resistance of electronic products under conditions of 100°C or higher and high humidity.
Since the test is conducted under conditions that are hotter and more humid than the normal environment in which electronic products are placed, the water vapor pressure inside the test chamber is considerably higher than the water vapor partial pressure inside the test sample.
This allows moisture to penetrate into the test sample, an electronic product, for a shorter period and can be used as an accelerated test to confirm moisture resistance.
Applications of Pressure Cookers
Pressure cookers can be used to check the penetration of moisture into electronic products under high temperature and humidity conditions.
In many electronic products, the circuit board is covered with resin, etc. If water penetrates into electronic products under high humidity conditions, it may affect the insulation resistance characteristics and aluminum corrosion inside the product. Therefore, electronic products are required to have durability against humidity. Since accelerated testing for humidity stress is possible, it is often included as a test item when electronic components are shipped.
Principle of Pressure Cookers
Pressure cookers require special equipment because they must be set at temperatures above 100°C and high humidity.
First, the test conditions are created by setting the temperature, humidity, and pressure in a test chamber. The test sample is placed in the test chamber for a specified period, and then several items are checked, including insulation degradation of the printed wiring board.
Types of Pressure Cookers
1. Unsaturated Pressure Cookers
Unsaturated pressure cookers are conducted in an environment of 85% humidity. This is one of the environmental tests for electronic products, and its criteria are specified in international standards.
2. Saturated Pressure Cookers
Saturated pressure cookers are conducted in an environment of 100% humidity. Since the humidity is higher than that of the unsaturated pressure cookers test, the water vapor pressure in the test sample can be extremely high, which accelerates the penetration of moisture and is therefore used as an acceleration test.