Vragen over elektronische productie beantwoord

In the design of a power electronic PCB, I want to use a metal PCB for heat dissipation of a TO-220 package MOSFET. To do that I want to mount

There is nothing about weight in the substrate datasheets I found.
Between CEM-3 or FR4, which is the lightest material ? What is the average weight by surface for

We are a green energy brand which sells solar water heater. All of our products are almost use PCB. And we want to know whether it is poisonous to human

I have a THERMAL problem when designing a power LED ALUMINUM PCB. I have 10 5W UV power LEDs.Coldwater flows through water heat sink continuously. The problem is the PCB

I am designing a micro-strip antenna with an HFSS toll, what’s the thickness of FR4 substrate that one should take ?

The power electronic converter is for high power application. I am going to design it for a new project. Any useful advice?