GB/T 39859-2021Gallium-based liquid metal (English PDF)

1 Scope

China's national standard for gallium-based liquid metals. Gallium melts at 30 degrees C, and alloyed with indium and tin it stays liquid well below room temperature - which gives a metal that is fluid at ambient without being mercury. That comparison is the point: gallium alloys have the electrical and thermal conductivity of a metal and the fluidity of a liquid, without mercury's toxicity and vapour pressure. The applications follow directly. They are the highest performance thermal interface materials available, conducting heat between a chip and its heatsink an order of magnitude better than any grease. They are used as flexible conductors in stretchable electronics, as the coolant in some high-flux applications, and in printed and reconfigurable circuits. The property that constrains them is aggressive alloying with aluminium, which they embrittle catastrophically - so the packaging and the surfaces they touch have to be specified with care.

This document specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation, storage, as well as accompanying documents and order forms for gallium-based liquid metals. This document applies to gallium-based liquid metals used for cooling fluids, conductive fluids, thermal interface materials, electronic pastes, and magnetic fluid materials.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.

GB/T 8170, Rules of rounding off for numerical values & expression and judgment of limiting values

GB/T 1024, Methods of viscosity measurement

GB/T 22588, Determination of thermal diffusivity or thermal conductivity by the flash method SY/T 5370, Test method for surface tension and interfacial tendon YS/T 1256, Nonferrous metal materials - Specific heat capacity testing - Differential scanning calorimetry YS/T 1257, Nonferrous metal materials - Enthalpies of fusion and crystallization testing-Differential scanning calorimetry YS/T 1258, Nonferrous metal materials - Melting and crystallization temperatures - Thermal analysis

3 Terms and definitions

The following terms and definitions are applicable to this document.

7 Marking, packaging, transportation, storage and accompanying documents...

8 Order form content

The order form for the products listed in this document shall contain the following:

a) product name;

b) product model;

d) packaging method;

e) special requirements, specified in this document, which shall be negotiated by both the supplier and the buyer;

f) reference to this document (GB/T 39859). A.2.2 Digital voltmeter It can measure the voltage of

0.01 mV ~ 100 mV; the measurement error is less than ±0.5%. The input impedance of the instrument shall be more than 3 orders of magnitude greater than the resistance of the sample. A.2.3 Probe It does not dissolve or react in the sample. It can be made of graphite, tungsten, molybdenum, etc. A.2.4 Conductivity cell In accordance with the structure in Figure A.1, the ratio of the cross-sectional area of the quartz container between the voltage probes to the length of the sample is not greater than

0.2 mm. A.2.5 Constant temperature bath Water bath or oil bath, where the temperature error at constant temperature should not exceed ±0.5 °C. A.2.6 Others Fixtures and spreaders for conductivity cells, probes. A.3 Test temperature In the range of 25 °C ~ 30 °C, not lower than the melting temperature of the sample, which shall be indicated in the test report. A.4 Test steps A.4.1 Set the temperature of the constant temperature bath to the test temperature; fix the conductivity cell in the constant temperature bath. A.4.2 Put the liquid metal sample into the conductivity cell; fix the four probes connected to the constant current power supply and the digital voltmeter at the preset positions according to Figure A.1. The height of the sample liquid level shall ensure that the tip of the probe is not less than