Elimination of Compromised Wirebonding on Ceramic MEMS Package Through Improved Process and Tooling Design

Wirebond stability is an important factor for a successful wirebond cycle. Wirebonding is a process used in the semiconductor industry to create electrical connections between the silicon chip and the leads or pads of its packaging. The process involves creating tiny wires that bond the chip to its package, enabling electrical signals to pass through. The step-by-step overview of a typical wirebonding cycle in semiconductor starts with die placement onto the substrate or lead frame of the package. For the microelectromechanical systems (MEMS) technology, several dies were placed and stacked on the ceramic. Ceramics are materials made from non-metallic minerals that have been permanently hardened by high-temperature heat treatment. They are typically characterized by their hardness, brittleness, heat resistance, and corrosion resistance. To continue the wirebond cycle to the next step is the electro flame-off followed by the formation of the first bond or ball. This is a combination of heat, pressure, and ultrasonic energy to bond the ball to a pad on the semiconductor die. The next step is wire looping, then stitch or second bond formation and the wire tear-off. The relationship of the ceramic during wirebonding has been a challenging factor in wirebond stability. Bouncing wirebond causes a non-stick on pad (NSOP) or lead error which is a result of a weak bond or no bond at all. NSOP can lead to device failure or reliability issues. It was known that the manufacturing operations used adhesive tapes to hold the ceramic on the stiffener. A known material was introduced with a higher adhesion level to mitigate the bouncing effect. However, due to thermal conditions on the wirebond requirement, an outgassing phenomena occurred. This caused other issues resulting to bouncing and unstable condition during wirebonding process. Other factors were also considered for the wirebond stability resolution.