How can I improve my wafer bump/Cu pillar reflow soldering process?
Building on our 25 years of proprietary and patented innovation for the global electronics packaging industry, Air Products has developed a novel flux-free soldering technology. It uses activated hydrogen at ambient pressure with a starting temperature as low as 100° C to remove metal oxides from electroplated solder bumps and copper pillars on semiconductor wafers and permits reflow of these bumps to obtain the proper shape and size for interconnection onto a package or substrate.
The activated hydrogen technology is a novel flux-free process, which can be operated at ambient pressure and normal solder reflow temperatures using non-flammable mixtures of hydrogen (<5 vol%) in nitrogen. This technology, invented by Air Products, involves generating a large quantity of low-energy electrons. Some of the electrons attach to hydrogen molecules, forming active species for effective oxide removal.
To capitalize on this unique technology, Air Products has partnered with Sikama International to introduce an electron attachment fluxless reflow system (EAUP1200) to the electronics wafer level packaging segment. The furnace is designed to remove metal oxides from solder bumps on UBM wafers and solder caps from copper pillar wafers via the activated hydrogen technology. The activated hydrogen produces hydrogen anions, which induces reflow of the solder to a final shape in the absence of traditional flux processes.