GB/T 14592-2014Molybdenum discs (English PDF)

Foreword

GB/T 14592-2014 was issued on 24 July 2014 by the General Administration of Quality Supervision, Inspection and Quarantine and the Standardization Administration of the People's Republic of China, and has been in force since 1 February 2015. It replaces GB/T 14592-1993.

The document is a recommended national standard: the /T in the designation marks it as recommended rather than compulsory.

1 Scope

China's national standard for molybdenum discs, the small round plates used as the base on which power semiconductor devices are built and as electrode and structural parts in vacuum electronic devices. Molybdenum is chosen for a physical reason rather than an electrical one: its coefficient of thermal expansion is close to that of silicon, so a silicon wafer soldered to a molybdenum disc can be heated and cooled through the thousands of cycles of a device's life without the joint tearing itself apart. It also conducts heat well and stands the temperatures of the joining process, which is what a power device needs, since almost all of its failures begin as heat that cannot get out. The standard specifies the requirements, test methods, inspection rules, marking, packaging, transport, storage, quality certificate and contents of the contract or order for molybdenum discs, and applies to discs used in power semiconductor devices and vacuum electronic devices. It classifies the product by grade and by delivery condition - blank, sandblasted, rough-turned, fine-turned, wire electrical discharge cut and ground - and lays down the designation, the chemical composition, a minimum density, and the permitted deviations on diameter and thickness for each condition.

This standard specifies the requirements, test methods, inspection rules, marking, packaging, transport, storage, quality certificate and the contents of the contract or order for molybdenum disc products.

This standard applies to molybdenum discs used in power semiconductor devices and in vacuum electronic devices.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document, including all amendments, applies.

GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection.

GB/T 3850 Determination of density for dense sintered metal materials and hardmetals.

GB/T 4325 (all parts) Methods for chemical analysis of molybdenum.

YS/T 660-2007 Designation and chemical composition of molybdenum and molybdenum alloy processed products.