Ceramic injection micromolds

How does Small Precision Tools make the small precision tools to mold its small precision tools? Is that your final answer? You’re right. It molds them.

SPT molds ceramic bonding capillaries, fiber-optic connectors, wear guides, and medical parts such as catheter components. Typically, its bonding capillaries are less than a half inch long with chamfered tips having 130-µm cross sections and 31-µm-diameter holes held to a tolerance of ±1 µm (see "Bonding tools" below).

Heinz Wiedmer, group manufacturing manager, says conventional methods of making cores and cavities for such parts simply can’t cut it. "How do you make them?" he asks. "CNC machining? EDM? Diamond grinding? No way. The parts have almost no draft angle, and the tolerance on the OD is only 6 to 7 µm. We manufacture core pins to mold a ceramic female cavity to mold a ceramic male core. The inserts are in tungsten carbide as are the core pins. These pins are the key. They make the holes in our capillaries."

Big Runs, Small Tools
Though wear-resistant and precise, Wiedmer admits that ceramic tools are prone to chipping and breakage. But, he says they last a long time when properly handled. The molds can easily run a million of the small shots required to make SPT’s small capillaries.

"We would not want less than 3000-part runs," Wiedmer continues. "We have about 150 different sizes of capillaries and regularly rotate our molds. After a run, we put the entire mold into our machine shop for maintenance, regardless of whether or not there is a problem."

SPT uses cold runners. Its two-stage Sodick press provides almost direct injection, obviating the need for runnerless molding.

Its mold bases are outsourced, but are finished at one of the company’s Swiss plants, and are shipped overnight. They last for years. Two-plate molds are used.

Wiedmer summarizes, saying the biggest challenge faced in molding SPT’s molds is being able to adapt to market needs for greater quantities of even smaller, more intricately shaped parts.

"In the early 1980s the tip hole diameters of our capillaries were as big as the back holes are today, and we are facing seven times the demand for our products that we were 10 or 15 years ago."

SPT’s product offerings have expanded significantly over the years, but the Petaluma division’s core business is still CIM bonding tools for integrated circuits (I/Cs).

The birthplace of PIM Where and when did the PIM industry begin? Many agree that it all began in the early 1970s in a little shop called Small Precision Tools located in Petaluma, CA. The company was co-founded by Karl Zueger in 1969. Zueger was looking for a more cost-effective, reproducible, high-volume means of manufacturing the small ceramic capillary bonding tools used to make semiconductors. Machining the tiny tools cost some $30 apiece.

Zueger hired a fellow named Raymond E. Wiech Jr., who was proposing what was then a revolutionary idea—injection molding ceramics. The rest, as they say, is history.

Zueger went on to start up another PIM molder in Petaluma, Parmatech, known today as Carpenter Parmatech—one of the global leaders in PIM. And Wiech went on to develop several key PIM patents that eventually transformed PIM into a growing, global business.

SPT continued developing its manufacturing technologies as semiconductor technology continued to advance. Then, in 1982, SPT merged with a Swiss firm with roots in the Swiss watch industry dating back to 1890. Today, the interdependent and fully integrated SPT Roth Group of companies operates several R&D, design, manufacturing, and marketing facilities in Switzerland, Singapore, the Philippines, and China, as well as in Petaluma. Customers include Texas Instruments and Intel.