The probe card is used to test the function of the bare die with probes before the chip is packaged. It is the interface between the tested chip (Chip) and the tester. It is a step in the wafer test that has a significant impact on the manufacturing cost. The yield rate of products tested with probe cards can be improved by nearly 20%.
According to the VLSI report, the global probe card market size was US$1.65 billion in 2018, and will reach more than US$2 billion in 2024, with an annual growth rate of more than 4%. The growth of the overall semiconductor industry has led to an increase in the use of probe cards for packaging and testing, of which Advanced Probe Cards are the main driver of growth.
Moore’s Law predicts that the number of transistors will double every 24 months, which means that the size of transistors needs to continue to shrink; this poses increasingly stringent challenges to packaging and testing requirements, and thus stimulates the rapid development of innovative packaging and testing technologies such as advanced probe cards. Compared with traditional probe cards, advanced probe cards show obvious changes: the number of probes is increased, the size of probes is reduced, the distance between probes is shortened, the thickness of materials is increased, the hole pattern is variable, and new materials are constantly being introduced. These development trends pose great challenges to the production of probes and all the components that make up the probe card. Among them, the key guide plate manufacturing is even more troublesome for traditional manufacturers.
Traditionally, the mechanical drilling process is used to process the guide plate, which is limited by the size of the drill bit. The diameter of the round hole that can be processed is generally above 40um, and the unilateral size of the special-shaped hole is above 100um. The minimum spacing that can be processed by this process is not less than 50um, and the processing time for a single hole exceeds 10 seconds. In order to reduce the contact force (touchdown) and production cost in advanced probe cards, a new policy structure has been developed in recent years, which has led to a surge in the demand for matching square hole guides. How to manufacture 30-60um square holes has become the most severe obstacle for all probe card companies to become world-class manufacturers.
GF’s mature laser micro-hole processing technology provides efficient and high-quality micro-square hole processing solutions. The ultrafast laser equipped with us has the characteristics of short pulse and high energy density, which will not cause burns around the processing material and no burrs on the hole wall. Taper hole, truly realize straight through hole and even reverse taper hole processing.
We develop exclusive processes for common materials in the probe card industry to maximize the processing efficiency of materials such as silicon nitride, alumina, and zirconia. This allows our integrated solution to machine a 35 x 35um square hole in 2 seconds with a fillet of only 3.5um and a achievable pitch of 7um; the heat affected layer in the surrounding area is negligibly small.
In addition to the exponentially increased efficiency, the consistency and reliability of laser processing are also valued by our probe card users. Imagine a probe card with 10,000 square holes. If any kind of defect occurs in the final processing stage, the whole probe card may be scrapped, and the lost time and money cost are considerable. The figure below shows that after 24 hours of continuous processing by the client, the size difference between the inlet and outlet of the micro-hole is within ±1um, which records the stability requirements of the equipment in detail.