What is Eutectic Die Attach?

university wafer substrates

Researchers Use Silicon for Eutectic Die Attach Trials

A posdoc requested a quote for the following:

We are looking for a source of silicon wafer for the purposes of eutectic die attach trials. If so we would be interested in wafers with no back metallisation wafers and thin gold for eutectic trials. The thickness of the wafers is not critical so something in the 375um region would be suitable. Our requirement would be only low quantities, one or two off 4 or 6” wafer would suffice.

Reference #202495 for specs and pricing.

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What is Eutectic Die Attach?

Eutectic die attach is a type of bonding technique used in microelectronics to attach a semiconductor die to a substrate. In this process, a eutectic alloy is used to join the die and substrate, forming a strong and reliable bond.

A eutectic alloy is a mixture of two or more metals or alloys that has a single melting point and solidifies as a single phase. When a eutectic alloy is heated above its melting point, it becomes a liquid with low viscosity, allowing it to flow and fill in the gaps between the die and substrate. As the alloy cools and solidifies, it forms a strong bond between the die and substrate.

Eutectic die attach is often used in high-temperature applications, as the eutectic alloy is able to withstand elevated temperatures without losing its mechanical and electrical properties. It is also commonly used in the assembly of high-power devices, where the strong bond and low thermal resistance provided by the eutectic alloy help to dissipate heat generated by the device.

What Substrates Specs are Commonly Used In Eutectic Die Attach Trials

The substrate used for eutectic die attach can vary depending on the specific application and requirements of the device being assembled. However, there are several substrate specifications that are commonly used in eutectic die attach:

  1. Material: The substrate material is often a ceramic material such as aluminum oxide (Al2O3) or beryllium oxide (BeO), although other materials like silicon, glass, or metal can also be used.

  2. Size: The substrate size is typically chosen to match the size of the die being attached, or slightly larger.

  3. Surface finish: The surface of the substrate is often polished to ensure a smooth and flat surface for the die to be attached to.

  4. Thickness: The thickness of the substrate can vary, but it is typically between 100 and 500 micrometers.

  5. Thermal conductivity: The thermal conductivity of the substrate is an important parameter, as it affects the ability of the eutectic alloy to dissipate heat from the die. High thermal conductivity substrates like diamond or copper tungsten are commonly used for high power applications.

  6. Coefficient of thermal expansion (CTE): The CTE of the substrate is an important parameter, as it must match the CTE of the die to prevent stress and cracking during thermal cycling. The CTE of the substrate is often matched to that of the die by selecting a material with a similar CTE, or by using an intermediate layer such as a thin metal foil.

  7. Metallization: The substrate may be metallized to provide electrical contacts for the die, and to ensure good electrical connectivity between the die and the substrate.