New processes are qualified at RFMD through a phase-gate process designed to ensure risks are identified as early as possible. Qualification plans are crafted to stress processes well beyond their intended lifespans and into the wear-out region of the bathtub reliability curve. Results are then used to establish reliability models from which safe operating areas can be defined for product designs.
Once a process is qualified, it is released to be designed into a product and combined with many other integrated circuits, surface mount components, and package materials. The product development lifecycle also follows a phase-gate process to ensure all areas of risk are addressed. The finished product is then subjected to an intense battery of stress tests to ensure there are no negative interactions between processes.
RFMD Product Quality Lifecycle Management Program
Product Quality Lifecycle Management Process Flow
- Technology Qualification - Qualification work begins with the reliability assessment of individual subcomponents and sub processes. This technology level qualification work may begin at an approved RFMD supplier or (in the case of RFMD internal manufacturing processes) may occur solely at RFMD. In the case of technology qualification work completed at suppliers, the results must be reviewed and approved by RFMD. Additional work may be necessary at RFMD to successfully approve an external technology for use by RFMD.
- Product Qualification - Once a technology is successfully qualified, it is integrated into a saleable product. Product qualification then commences with the goal of evaluating all sub processes and subcomponents as they exist in the form of a completed product.
- Early Production Phasing - Once a product is successfully qualified, it may be selected for a period of highly intensive, large sample size testing known as early production phasing. The goal of phasing is to closely monitor representative products and technologies as they are “phased-in” to high volume manufacturing processes. Large samplings of parts are selected on a weekly basis to assess process stability and reliability across the manufacturing process. These parts are then submitted for a set of core reliability tests such as moisture sensitivity level (MSL), temperature cycling, solderability, and unbiased Highly Accelerated Stress Test (HAST).
- Ongoing Reliability Monitoring (ORM) – After product qualification and early production phasing are complete, representative technology platforms are re-evaluated on a quarterly basis to assess reliability over time. Core ORM tests include solderability, MSL, temperature cycling, and High Temperature Operating Life (HTOL).
General Requirements for Reliability Testing
- Unless otherwise indicated, pass/fail criteria are dictated by comparison of an approved pre- and post- stress electrical test suite.
- For tests requiring multiple assembly lots, each lot must (as a minimum) be from a non-consecutive assembly build (i.e. non-consecutive shifts).
- Whenever possible, process lots shall be deliberately chosen to reflect demonstrated or anticipated production variability. The appropriate process parameters investigated should in turn be based on risk defined by a Potential Problem Analysis (PPA) which reflects thorough understanding of failure modes of the technology.
- Any failures encountered during qualification shall be investigated through electrical and physical failure analysis in order to determine root cause. All failures shall be dispositioned through root cause explanation or corrective action prior to product release.
Product Qualification – List of Stress Tests
- All RFMD products undergo a core suite of reliability stress tests. A description of each test is given for clarity. The list is not comprehensive. Additional reliability tests may be added for particular products to address risks identified through product level PPA or by customer request. When appropriate generic data may be used to fulfill sample size requirements.