New mass imaging process enhances TIM at a stroke

Citation

(2004), "New mass imaging process enhances TIM at a stroke", Soldering & Surface Mount Technology, Vol. 16 No. 1. https://doi.org/10.1108/ssmt.2004.21916aad.016

New mass imaging process enhances TIM at a stroke

New mass imaging process enhances TIM at a stroke

Keywords: Imaging

DEK has successfully applied mass imaging techniques to improve the uniformity of thermal interface material (TIM), deposited between a silicon die and its package lid during semiconductor packaging processes (Figure 1). By mass imaging the TIM using ProFlow DirEKt Imaging, semiconductor manufacturers can now be sure that the die surface is covered by a uniform thickness of TIM. Advantages include better thermal connectivity between the die and lid, which improves reliability, as well as greater coplanarity of the lid.

Figure 1 The new mass imaging technique applied by DEK improves the uniforming of TIM

DEK will also soon conclude development of a lid sealing process that will complement its TIM deposit process to create a complete mass imaging solution for lid attachment.

Die that have been assembled onto substrates enter a flexible printing platform that combines three processes, passive attach, TIM and lid sealing, into a single platform, giving the customer the flexibility to re-deploy equipment between processes to meet the changing market demand and to respond to future. In addition, operators only need to be trained on one platform, and spares inventory is also streamlined. Compared to traditional dispensing processes, mass imaging increases true throughput and delivers greater control over the volume of material deposited.

Mass imaging also allows the shape of the TIM deposit to be more accurately controlled, and more repeatable. The thickness of the initial deposit is also more uniform across the surface of the die. Because the process does not rely on placing the lid to spread the TIM, flaws such as voids in the material or incomplete spreading are eliminated. This is very important to semiconductor manufacturers and packaging specialists, since these flaws are very difficult to inspect after the lid has been placed.

TIM is frequently used when packaging semiconductor components that must dissipate substantial amounts of heat. The material has a high coefficient of thermal conductivity, and fills the void between the upper surface of the silicon die and the package lid. The package lid is subsequently bonded to the device’s substrate. During operation of the device, the TIM will conduct heat away from the die to the package surface, from where it can be dissipated efficiently by convection from the surface of the lid, by an external heatsink or by forced air cooling using a fan.