UAT: Blowing the Doors off Capacity

In July, 2010, Unisem Advanced Technologies (UAT)—a 3-party joint venture between Unisem Group, Advanpack Solutions, and FlipChip International— announced a facility expansion at its wafer bumping facility in Ipoh, Malaysia, that would reportedly triple its capacity. Chip Scale Review decided to check in and see how progress has been since then. We interviewed S.C. Lau, General Manager of UAT’s bumping operation. SC has been with Unisem for five and a half years, and through that time has seen tremendous growth in the operation.

CSR: First, let's talk background: How and why did Unisem, Advanpack Singapore and FlipChip International first come together to form Unisem Advanced Technologies?

SC: In 2004, a joint venture was established between Unisem and Advanpak Singapore to manufacture copper pillar bumps, which was very new to the market. In 2008, FlipChip International joined as a partner to expand the portfolio of options to include other bumping processes. As a result of licenses with two major parties (FCI and APS) our portfolio is wide and we can offer gold bumps, copper pillar bumps and solder bumps. Additionally, FCI still operates as a separate entity. If we have US customers who want to do their bumping onshore in low volumes, we send them there. Conversely, FCI refers high volume jobs to us in Ipoh.

CSR: You mention gold, copper and lead-free alloys as bumping materials. Does UAT also use lead solder for its bumping?

SC: We made the decision to go with 100% lead free materials and not participate in eutectic lead solder bumping because the market trend is moving away from lead and becoming more environmental. Our position as a group is that we focus on new package technologies, developed with green bill of materials. Some customers may have specific reasons for lead plating, but it's a narrow focus.

CSR: What are the different bumping technologies, and what applications are they each best suited to?

SC: Our bumping services include ball-drop, plating and solder printing. Ball drop is our leading process targeting handheld devices with pitches still between 400 and 500µm, but moving to 250 µm pitch for wafer level chip scale packages (WLCSP) because it’s the most cost-effective. As we get to finer pitches, there are advantages to switching over to copper pillar bumps. It depends on application. Customers who are motivated by performance will go with copper pillar for power management where thermal and electrical performance is important. General applications will stick with solder bumps which offer lower pricing. Gold bumping is a process we also offer, but it’s mainly used in medical devices such as hearing aids, or in LCD displays; it’s very specific to certain applications.

CSR: What has the demand been like for UAT since the formation of the joint venture?

SC: In October of 2009, I requested $1M from the budget to expand our chip packaging location. By January, I had to increase that to $3.5M to keep up with the demand from customers. Again in July, to cope with the demand that number needed to be increased once again to $10M, which was used to expand the capacity of the maxed out facility. We had to increase capacity by adding an entire second floor. That capacity has also been used up – basically, the demand is greater than we can supply.

CSR: Are there any plans for expansion beyond 200mm, or to add capacity to additional locations?

SC: We offer 4", 6" and 8" (200mm) wafer processes. 8" is still the major volume in the market. It would be too complicated to add 300mm capacity to the UAT facility in Ipoh, because it would require entirely new equipment lines. Rather, the concept for the Ipoh facility is to make it a location where a customer can send a wafer for bumping, WLP and final test; everything from start to finish.

CSR: Any major plans for 2011?

SC: UAT needs to squeeze as much capacity out of the facility that we can. As a result, this year we’ll be looking at incremental capacity buys, around $3M capex total. That said, we are considering our Chengdu location for added capacity, with the long-term plan to add 300mm bumping there. We chose Chengdu due to its location near the fabs in China.