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Verdant Electronics Provides Alternative to Lead-Free Solder for Circuit Boards
Dean Takahashi, Contributing Editor -- Design News, August 7, 2007
Joseph Fjelstad felt that lead-free solder was a wrong turn for the electronics industry. So the man with 120 patents in electronics packaging and related fields decided to create a way to make circuit boards without solder altogether.
The 58-year-old Fjelstad announced last week that his startup, Sunnyvale-based Verdant Electronics, has come up with a solution that he says is more efficient, cost-effective and environmentally sound than lead-free solder. If he’s right, the industry can get rid of the solder-based printed circuit boards that have been around since the 1920s and use Verdant’s “Occam Process” for high-volume consumer electronics products.
“I’ve been looking into lead-free solder for seven or eight years,” said Fjelstad, a former fellow at chip packaging firm Tessera. “Initially, I thought it was a good idea. The more I dug into it, the less certain I was. Maybe that’s why the muse talked to me. I had a bolt of lightning. This was a way to get around it.”
Typical circuit boards consist of packaged integrated circuits that are placed into holes in a circuit board using a surface mount machine. The machine spreads solder paste over the holes and the excess is scraped off. The solder is baked at a high temperature so that it melts and establishes a permanent connection between the chips and the board. With lead-free solder, even higher temperatures are required.
With Verdant’s process, named after 14th century English philosopher William of Occam for its simplicity, the packaged ICs are encapsulated in a tough epoxy. Fjelstad calls it “reverse order processing” because normally you build a circuit board and then place chips on it.
Verdant proposes to start with the components sitting in their correct positions on a base platform. Then the insulating epoxy is overmolded on top of the components. Lasers are used to drill holes for component leads. And copper vias are plated along with the circuit layer, followed by a coating of insulating material. The candidates for the epoxy include a variety of off-the-shelf materials currently in use in the industry.
Since the chips will be encapsulated, heat could be an issue. But Fjelstad says that heat spreaders and even heat pipes can be designed directly into the epoxy, which becomes the equivalent of the substrate of the printed circuit board.
There is a huge amount of momentum behind solder and printed circuit boards. When Fjelstad first joined the electronics industry in 1972, they were in use. General Electric experimented with putting bare die down and interconnecting them in the 1990s. But the progress languished. Conductive adhesive was tried, but reliability was poor.
Fjelstad said the company is making prototypes now and has received good feedback since its announcement. He expects military electronics companies to be the most enthusiastic customers because they often have devices that can’t use lead-free solder. While they have exemptions that allow them to use lead, the supplier base for lead-based solder is starting to dry up because of the European requirement to shift to lead-free solder. Fjelstad said the company has applied for seven patents and its raising capital.
Ultimately, he hopes the benefits of the Occam Process will overcome the momentum behind lead-free solder. Those benefits include better compliance with Europe’s environmental regulations, less vulnerability to mechanical and heat shocks, simpler electronics designs, fewer manufacturing steps and lower costs.
Alan Rae, a packaging expert at NanoDynamics, says that the Verdant process uses existing processes currently used to make high-volume products like cell phone circuit boards but it applies them in a novel way to create a “potentially low-cost integrated circuit board assembly and packaging solution that is ‘green.’”
“Solder for many years was the servant of the electronics industry,” Fjelstad said. “Now it is the master and everything is bending to meet the needs of the solder. I am questioning that. This is a master once benign but now not so kind.”
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