What is a Clean Room?
The heart of any semiconductor assembly line is a clean room that utilizes advanced equipment such as fully-automated die attach machines and state-of-the-art wire bonders. However, all this equipment would be meaningless if it were not for the clean room specifications that ensure that the final product meets the hi-reliability standards set by the military and aerospace industry.
Clean Room Requirements
Golden Altos has an integrated circuit assembly clean room for both monolithic and hybrid devices that was designed from the ground-up to meet the stringent requirements set forth by the Military and Aerospace Industry, and is currently maintained by our internal specifications. The current rating for the entire cleanroom meets ISO Class 6 standards (previously Class 1000), meaning that there are no more than 35,300 particles larger than 0.5 µm/m³. Golden Altos has also implemented a 5S Manufacturing Methodology to assist in maintaining order and cleanliness throughout the facility. ESD clean room bunny suits, shoe covers, hoods, and face masks must be worn before entering the air shower room to remove loosely attached particles.
Foreign contamination is a serious problem that can severely affect the reliability and function of any semiconductor device. Airborne particulates must be controlled, and there are different class limits as required by the military standards governing microelectronics such as MIL-PRF-38534, MIL-PRF-38535, which refer to ISO 14644-1, and ISO 14644-2. Both MIL-STD-750 and MIL-STD-883 have specific inspection criteria for foreign material.
Clean Room Readings
While the overall rating for the clean room is ISO Class 6, critical processes are done under a laminar flowhood equipped with HEPA (High Efficiency Particulate Air) filters to achieve an ISO Class 5 environment (previously Class 100; no more than 3,530 larger than 0.5 µm/m³). Critical processes include, but are not limited to: wafer film attach, wafer saw, wafer wash, die plate, die attach, adhesive dispense, wire bond and wire pull equipment are also located under the same flow hoods. Seal operation using the seam sealer, welder, CDA IR furnace, and Nitrogen atmosphere furnace are too large to be placed under a flow hood but are still within the clean room environment with particle counts that meet or exceed the ISO Class 6 (previously Class 1000) standards. All processes performed in both the ISO Class 5 and ISO Class 6 environments are closely monitored by performing particle count checks daily during normal work hours and operations.
Maintaining High Environment Standards In Our Clean Rooms
The environment of the clean room is also maintained for temperature and humidity by an internal Golden Altos specification following military requirements with additional safeguards. The acceptable temperature range is 67°F to 75°F and the humidity is at 35% to 55% RH to prevent ESD (Electrostatic Discharge). Golden Altos also has an HVAC (Heating Ventilation and Air Conditioning) system that will maintain humidity and temperature control that will meet or exceed military requirements.
5S Lean Manufacturing Methodology
In addition to complying with MIL-PRF-38534 and MIL-PRF-38535, Golden Altos has also implemented the 5S Lean Manufacturing Methodology to aid in the day-to-day operation and organization of processes and materials on-site. This system aims to increase the value of products or services for customers by finding and eliminating waste from production processes.
The steps for the methodology are as follows:
1. Sort: Identify essential tasks, tools, and processes.
2. Set in Order: Organize, detail, and arrange tools and materials for easy accessibility
3. Shine: Maintain a clean and tidy workplace
4. Standardize: Establish consistent rules and guidelines that everyone can follow
5. Sustain: Actively practice the 5S Methodology in the workplace on a regular basis