Abstract
The miniaturization and increasing complex integration of functional chips handheld devices such as cellular phones have led to the widespread adoption of chip scale packages (CSPs) and ball grid array (BGA) packages. Lighter weight, thinner thickness, smaller size, high I/O pins, low cost, high functions, high quality and green environmental material are trend of IC packages and continuously challenge manufacturer and material supplier to develop new technologies and new materials to meet the process requirements in packaging. Ball-grid arrays (BGA) packages which place output pins in the form of a solder ball matrix provides effective solutions for high capacity interconnections and efficient thermal management of the power ICs. The I/O connections of the BGA are generally fabricated on laminated substrates (BT-based) or polyimide-based films. Therefore, the entire area of substrate can be used to reroute the interconnection. BGA has the advantage of lower ground or power inductance thereby assigning ground or power nets via a shorter current path to PCB. The higher functional capabilities of the BGA package technology benefit high power and high speed ICs that require enhanced electrical and thermal performance. However, in BGA packaging the issue of delaminating between molding compound and wire bonding pad on the ENEPG (Electroless Ni Eletroless Pd immerse Gold) substrate after product pre-con test has been an issue to liability test defined by Joint Electron Device Engineering Council (JEDEC). A wide range of treatments have been developed to enhance adhesion. Some involve aggressive chemical treatment. Strong oxidising solutions, such as chromic acid or permanganate have been employed with hydrocarbon polymers, and highly reactive combinations such as sodium in liquid ammonia have been used for fluorocarbons. Alternative pretreatments to 'wet' chemical treatment include surface flaming, the action of gas plasma or reactive ion etching [1, 2, 3]. But, factors of post clean and cost are needed to be considered. Possible solution such as changing molding compound material with improved adhesion to the surface of the ENEPG substrate, but will be cost by time for process assurance procedures and documentation. In this paper, we present solutions to improve as well as to eliminate delaminating problem without changing standard packaging flow and material system.
Published Version
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