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36 The PCB Magazine • June 2017 face in standard technology on the surface of the PCB measured 188.5°C at the component hot spot. By placing the same MOSFET type components inside of the PCB construction, the temperature was reduced by 106°C to an operating temperature of 82.5°C. The thermal heat from the component was distributed over the total area of the PCB. For an electronic en- gineer, this could impact the total layout of a PCB and it could also help in miniaturisation of electronic devices and equipment. Cost reduc- tion could also be achieved if no external cool- ing is needed. The photographs and the tem- perature measurements were taken by a thermal camera. The impact on heat conductivity factor of the epoxy resin (0.35 W(m.k) and the glass fi- bre (1.05 W(m.k) in the PCB material provides a more than 10x improved thermal conductivity compared to air (0.024 W(m.k). Resistance to water and other liquids In Figure 6 an example is shown that demon- strates LEDs embedded in a CCL material used in fabrication of PCBs. These materials are resistant to many liquids. These strips are connected to power and have been lighting partially in wa- ter partially in air since more than five years. In some applications, this CCL with embedded de- vices is used in hot oil and other hot liquids. Em- bedded electronic devices in CCL are also used in gearboxes to manage the electrical functionality at the gearbox temperature. The exposure to hot gearbox oil is of no issue for the device embed - ded technology PCBs. These sensor modules (Figure 7) are placed in small areas. They must be cost-effective in manufacturing. Embedding components is an outstanding way to miniaturise surface area of the unit through an effective design for manu- facturing. Small unit designs manufactured us- ing large panel processes offer an opportunity to lower manufacturing cost. At the same time, high product reliability is achieved as all elec- tronic components have excellent protection against humidity, oil, shock, temperature and EMC impact by other uncontrolled radiation and frequencies. Manufacturing PCBs with Embedded Devices Over the last 20 years, many tests have been conducted. This was needed to define reason- able design rules that will enable the use of standard packaged components as well as to allow sufficient epoxy resin for a reliable bond strength during the press cycle. In addition, air entrapments or voids must be avoided. This could have an impact on signal speed and insu- lation characteristics of the dielectric material. Figure 4: The fabrication process for embedding devices in PCBs, Part 2. EMBEDDING ACTIVE AND PASSIVE COMPONENTS IN ORGANIC PCBS