Membrane Probe Card Research Articles

Fabrication of a micro-tip array mold using a micro-lens mask with proximity printing

In this study, a mold for a micro-tip array is fabricated using a microlens array mask with proximity exposure. The micro-tip array uses a microlens array mask with geometrical optics. Light passing through a microlens is focused at the focal points. There is microlens on the mask and the pattern that results from the light passing through the mask is directly projected onto the photoresist surface. A concave profile is developed using a positive photoresist and the remaining photoresist microstructures are formed after the development process. By changing the distance between the mask and the photoresist and the radius of curvature of the microlens, various tip shapes can be fabricated. The exposure gap is calculated using the microlens array mask and the geometry of the mold of micro-tip array is established using the irradiance absorption maps for the different levels. These methods respectively use the model of the positive photoresist and optical software. When electroforming a metallic micro-tip copy of the patterned photoresist, masters are created. The metal micro-tip array is used membrane probe card.

Fabrication of a membrane probe card using transparent film for three-dimensional integrated circuit testing

We fabricated a novel membrane probe card using a transparent film for the chip-level testing of a three-dimensional integrated circuit (3D-IC). In this membrane probe card, 20-µm-pitch Ni–Au contact bumps and Ti–Au wirings were formed on a biaxially oriented poly(ethylene naphthalate) (PEN) film. This probe card was fabricated using a low-temperature (lower than 100 °C) process, which included through-hole formation by a laser beam, photolithography, Ar plasma irradiation to improve the adhesion between the PEN film and the metal wiring, Ti–Au sputtering, Au electroplating, Ni electroplating, and electroless Au plating. The probe card has three characteristics: (1) fine pitch probes. (2) small-gap alignment between the probe card and the tested chip owing to transparency of the probe card, which offers high accurate probing. (3) damageless (low-load) probing owing to the compliancy of the PEN film. Using this probe card, we performed pre-bond testing of a 10-mm-square chip with Cu–SnAg bumps. The probing to 20-µm-pitch, 1,000 Cu–SnAg bumps and the pre-bond testing of thin Si chips were realized without causing damage to the chip even when chip was very thin (50 µm thick).

Flexible MEMS probe cards for three-dimensional probing

The results of examining substrate performance in the development of an integrated circuit membrane probe card are presented. Silicon, glass, Kapton™ and HDPI2525™ polyimide are examined as substrate materials, each having its own individual advantages. The fabricated device involved a simple electroplated design with good electrical addressability and excellent mechanical properties. Comparisons are made between the different substrate materials; potential devices and situations where each could be implemented are provided. Silicon gives optimum adhesion, glass provides excellent alignment and Kapton™ is useful for significant z-plane deflection.

Six-Gigahertz Equivalent Circuit Model of an RF Membrane Probe Card

Installed on manufacturing probe stations, the membrane probe card is a production test board for high-volume radio frequency (RF) wafer testing. Replacing dc needle probes with an RF membrane probe permits RF measurements at the die level. Both physically and electrically, the membrane probe resembles the components and packaging of the final product. Die tested using a properly designed membrane probe card should exhibit RF performance comparable to an assembled component. To guide an effective membrane probe-card design, it helps to have a well-characterized example. This paper details a lumped-element equivalent-circuit model of an RF membrane probe card, suitable for reference in designing general-purpose RF membrane probe cards. Along with the equivalent-circuit model, the characterization methodology is discussed