The increasing use of AlN or Aluminium Nitride in power electronics, dissipating heat and providing electrical insulation has been an ongoing trend. The performance of Aluminium Nitride far outstrips Aluminia in some critical areas, but the added cost of manufacturing AlN is a limiting factor.
The changeover from Aluminia to AlN takes you from a material that is plentiful and one of the cheapest technical ceramics, to a relative newcomer, requiring specialist furnacing in a nitrogen atmosphere and limited specialist manufacturers. The move from one material to another is a major step-change although, with significant benefits, this can carry significant cost increases and longer lead times.
The move to AlN can be mitigated by using an intermediate step, a machinable Aluminium Nitride, this can help considerably when developing a structural piece of material that can not be produced from the available ceramic substrates but requires a larger piece of material that would otherwise have to be made from compacted powder and sintered.
Machinable AlN is a hot-pressed material, produced in a billet form, easily machinable, and readily available. This allows a rapid turnaround and a way of quickly prototyping small quantities of components without waiting months for minimum order quantiles of parts.
Machinable AlN, with the Trademark Shapal Hi M soft, is the market leader, with a 30-year pedigree, this tends to be the material of last resort when you have reached the extremes, of temperature, thermal shock, electrical insulation, whilst having the ability to be machined without diamond tools.
Aluminium Nitride is mechanically stronger, harder and has a higher thermal conductivity. The downside being availability, lead time and the cost of diamond grinding which can add considerably.
The transition from Aluminia to a higher-performing thermal material such as AlN can require tooling and long lead times, Shapal Hi M soft can provide the bridge, where small quantities of prototypes can be rapidly produced, trialed and evaluated, modified in design if required and then retested, without having to place significant orders, pay for tooling and wait for months.
The ability to rapidly make machinable Aluminium Nitride components shortens time to market and allows a fully functioning product to be tested. Many products have been developed this way and a considerable number have stayed with the Shapal Hi-M Soft and not made the transition to AlN.
This table shows the key benefits of Aluminium Nitride vs Machinable Aluminium Nitride:
|Properties||Test Conditions||Aluminium Nitride||Machinable Aluminium Nitride |
(Shapal Hi-M Soft™)
|Density||Corrected to 4℃||3.31||2.88||g/cm3|
|Volume Resistivity||25℃||1.0 x 1013Ω . cm||1.0 x 1015Ω . cm||Ωcm|
|500℃||3.2 x 107Ω . cm||3.2 x 1010Ω . cm||Ωcm|
|Thermal Expansion Coefficient||RT to 300℃||4.6 x 106||/℃|
|RT to 400℃||4.8 x 106||/℃|
|RT to 500℃||5.2 x 106||/℃|
|RT to 600℃||4.9 x 106||/℃|
|RT to 800℃||5.0 x 106||/℃|
|RT to 1000℃||5.6 x 106||/℃|
|Thermal Conductivity||25℃||180||92||W/m. K|
|Maximum Use Temperature||in air||1000||1000||℃|
|in non oxidizing atmosphere||1900||1900||℃|
|Vickers Hardness (Hv)||25℃, 300g||1100||380||kg/mm2|
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