A probe card is utilized in the field of integrated circuit (IC) manufacturing before packaging, to perform functional tests on bare chips using probes. This process helps identify defective products and prepares them for subsequent packaging processes. Thus, it plays a significant role in the manufacturing cost of integrated circuits. The probe card can enhance the yield of finished products from the original 70% to 90%. Even a 1% yield difference, which can be contributed by a 20% increase in yield, holds immense importance for semiconductor manufacturers.
In essence, a probe card serves as an interface between the testing machine and the wafer, ensuring that only good products proceed to the next packaging phase after wafer dicing, preventing wastage of defective items. Therefore, high reliability is a crucial indicator of competitiveness for probe card manufacturers.
Depending on the application, probe cards in the field of IC testing can be categorized as Epoxy Ring Probe Cards, Vertical Probe Cards, and MEMS Probe Cards. Let's delve into a further technical analysis of the Epoxy Ring Probe Card and the MEMS Probe Card.
Epoxy Ring Probe Card Technology Analysis
Since its introduction in the 1970s, Epoxy Ring Probe Card technology has become a widely adopted testing solution in the semiconductor industry due to its advantages of rapid production, small quantities, and versatility. The manufacturing process involves designing Mylar drilling and fixtures based on pad assignments, manually placing probes one by one, attaching the probes to complete the Epoxy ring probe head, connecting the probes to the printed circuit board (PCB) through soldering, and finally ensuring co-planarity on a needle grinder. While Epoxy Ring Probe Cards offer advantages in terms of speed, quantity, and versatility, there are still some inherent design flaws that limit their application scope.
MicroSpring Probe Card Technology Analysis
To overcome the technical limitations of traditional Epoxy Ring Probe Cards in DARM testing, FFI in the United States introduced the MicroSpring probe card. This type of probe card features nearly uniform force distribution among the probes and a set of horizontal adjustment mechanisms, enabling the development of its unique multi-dut testing technology. Specifically, MicroSpring probes are fixed to a Space transformer using methods like brazing, soldering, and welding. The Space transformer is generally a Multi-Layer Ceramic substrate (MLC), offering a well-defined horizontal reference plane and circuit redistribution. With the help of an adjustment mechanism based on the MLC's horizontal reference plane, MicroSpring probes achieve excellent co-planarity.
Based on the above analysis, it's evident that the core technology of such probe cards lies in the manufacturing of MicroSpring probes. This technology determines its potential to meet the needs of semiconductor pin testing and its applicability to various product categories.
Integrated Probe Card Technology Analysis
To break FFI's monopoly in the global DARM testing market, improve throughput, and develop probe card technology with finer pitches and higher pin counts, the Mechanical and Systems Research Laboratories of ITRI proposed the concept of Integrated Probe Cards, leveraging Micro-Electrical-Mechanical Systems (MEMS) technology.
Integrated probe structures combine microfabrication processes such as high aspect ratio lithography technology, dry/wet etching technology, high hardness electroforming technology, and planarization technology. This results in all probes being formed as a single unit, overcoming the limitations of manual assembly of probes seen in Epoxy Ring Probe Cards and the individual soldering process in MicroSpring Probe Cards. This higher level of automation breaks the limitation of production cost scaling with pin counts, which is beneficial for manufacturing high pin-count probe cards.
Related Application and Products
Probe Pin
Printing Circuit Board (PCB)
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