With the rapid development of 5G communication, data center interconnection, and AI computing infrastructure, the application of 400G/800G high-speed optical modules is becoming increasingly popular. As the core component of optoelectronic conversion, the reliability of optical modules directly determines the operating life and failure rate of communication systems.
Optical modules can be classified according to multiple dimensions. According to the packaging form, mainstream types include SFP/SFP+/SFP28 (small pluggable), QSFP/QSFP+/QSFP28/QSFP-DD (four channel/dual density four channel), OSFP (eight channel small pluggable), CFP/CFP2/CFP4 (C-type pluggable), etc. According to the speed level, from 10Gb/s and 25Gb/s to 400Gb/s, 800Gb/s and above, the higher the speed, the more stringent the reliability requirements for optical devices and packaging processes. According to temperature levels, it can be divided into commercial grade (0 ℃~70 ℃, suitable for indoor environments such as data center rooms), industrial grade (-40 ℃~85 ℃, suitable for wide temperature environments such as outdoor cabinets and base stations), and expansion grade (-20 ℃~85 ℃).
The reliability test of optical module environment is divided into two categories: non working environment test and working environment test. The non working environment test includes four main items: high temperature storage: temperature of 85 ℃, duration of 2000 hours. Low temperature storage: temperature -40 ℃, duration 72 hours. Temperature cycle: According to MIL-STD-883G method 1010.8, the temperature range is -40 ℃ to 85 ℃, with 500 cycles, and the temperature change rate is required to be ≥ 10 ℃/min. Constant humidity and heat: 85 ℃/85% relative humidity, lasting for 500 hours. Work environment test: mainly for high temperature life test, with a test temperature of 70 ℃ or 85 ℃, lasting for 2000 hours under normal working conditions of the optical module. After the completion of various tests, the change in key performance indicators of the optical module before and after the test must be ≤ 1.0dB (1.5dB for the lifespan test).
The HAST aging test chamber is mainly used to evaluate the reliability of products or materials in a humid environment. It is achieved by setting and creating various conditions of temperature, humidity, and pressure in a highly controlled pressure vessel. These conditions accelerate the penetration of moisture through the external protective plastic packaging and apply these stress conditions to the material body or product interior.
Supporting conditions for conducting optical module testing using HAST aging test chamber
1. Bias feedthrough component: The pressure vessel wall is sealed and feedthrough, which leads the power supply and I2C DDM signal out of the box; Direct penetration of ordinary cables can cause pressure vessel leakage and safety risks.
2. Optical module dedicated carrier board: resistant to high temperature and humidity of 130 ℃, cannot use ordinary PCB carrier board; Supports SFP/QSFP-DD/OSFP sockets.
3. External monitoring equipment: external error code meter and optical power meter connected to the box, comparing the optical and electrical performance indicators of the optical module before and after the test.
4. Post test processing: After the sample is taken out, it is dried at room temperature and then subjected to performance testing to avoid misjudgment and failure caused by condensation water.
HAST aging test chamber is used for two modes of optical modules
1. U-HAST (unsaturated mode, mainstream optical module): controls humidity at 85% RH, does not reach 100% condensation saturation, and the chamber will not have a large amount of condensation and dripping water. Principle: In a high temperature and high pressure environment, the partial pressure of water vapor is controlled to maintain a relative humidity of 85% RH; there will be no liquid dripping to soak the sample, avoiding non real failure caused by direct immersion of the sample in liquid water. Almost all optical module testing uses the U-HAST mode.
2. B-HAST bias charging mode: The power supply and I2C signal are transmitted through the pressure vessel wall and led out to the outside through the pressure vessel dedicated sealed feedthrough terminal. The sample operates under high temperature, high pressure, and high humidity conditions when powered on; After the invasion of water vapor, ion migration, electrochemical corrosion, and leakage short circuit are excited under the action of an electric field, simulating the corrosion failure under actual charged use.
The HAST aging test chamber is based on the principle of a sealed pressure vessel, which generates high-temperature water vapor through heating to increase the internal pressure of the chamber. The pressure difference is used to drive the rapid infiltration of water vapor into the gaps and interfaces of the sample, achieving accelerated activation of wet heat failure; Implement U-HAST unsaturated mode through closed-loop control to avoid a large amount of condensation water. The optional high-voltage sealed feedthrough component can achieve B-HAST bias voltage live testing, which is used to evaluate the reliability of non gas sealed optical modules against water vapor penetration and electrochemical corrosion.