Japanese LED manufacturer Yokowo has launched Low Temperature Co-fired Ceramic (LTCC) Chip Scale Package (CSP) substrate to lower LED package costs, reported Nikkei recently.

The new 0.075 to 0.150mm thick substrates have high thermal dissipation and reflectance, and are using silver (Ag) conductors are used as electrode materials. Thermal dissipation boards are used in the LTCC substrate combined with thousands of miniature CSP. Bond pads are used in the front or back opening of the CSP during the package process.

On average, high brightness LEDs only convert 25% of energy into light, while the remaining energy is lost through the form of heat. Higher LED temperatures lead to lower energy efficacy. Hence, LED clients have been demanding for LED packages with better thermal dissipation. In high power LEDs, there has been an increasing usage of aluminum oxide (Al₃O₂) substrates and aluminum nitride (AlN) ceramic substrates.

However, AlN substrates have much lower reflectance and precision in LED sizes. Hence, AlN substrate based LED packages tend to be less reliable. In addition, AlN substrates can be quite costly. Therefore, Yokowo has developed LTCC substrates which has better thermal dissipation properties, and supports smaller and thinner substrates that can help manufacturers lower manufacturing costs.

The rim of the LTCC substrate is an integrated structure that uses a slightly thicker “external frame” than CSP, which improves the chip package process. In addition, the company has also developed a technology to strengthen the bond between the substrate and LED chip, and brought size marginal error to within ±0.15％. The surface of the chip is processed using Ni-Au.

LED package manufacturers are sampling and evaluating Yokowo’s LTCC substrates. The substrates will be manufactured at LTCC’s advanced component center in Tomioko, a city located in southwestern area of Gunma Prefecture. The company is constructing a new 500 m² factory, which is expected to be completed by late May 2015. The company will be initially manufacturing 500,000 LTCC substrates (sized 50 mm) per month, and each substrate will be equipped with thousands of 1.0×1.0×0.15mm CSPs. The company plans to mass produce the new substrate sometime after October 2015.