Integrated Circuits packaging

With a sustained increase of over 8% per year since 1985, electronics are now present everywhere in our daily and professional lives. Sales of electronic components alone accounted for nearly $340 billion in 2016, 80% of which was for integrated circuits alone.

This sustained growth in microelectronics has always been driven by the emergence of new applications: infrastructure electronics in the 80s, PCs at the turn of the 90s, the Internet at the end of the 20th century, then more recently nomadic applications (smartphones in particular) and finally the Internet of Things (IoT). Packaging has supported this growth thanks to three major technological breakthroughs:

• the widespread use of surface-mount boxes (SMD) from the mid-1980s;

• the introduction of housings on organic substrates from the mid-90s, which enabled a significant increase in the number of contacts (from purely peripheral contacts to contact arrays);

• the widespread use, from the mid-2000s onwards, of dedicated boxes for each application.

The primary function of packaging is to make integrated circuits easy to handle, and thus to establish the electrical interconnections with the customer circuit (printed circuit board) thanks to standardized formats (identical for all manufacturers). Of course, packaging also helps to dissipate the heat generated during operation and protect the microelectronic chip from the environment, thus contributing to the component's reliability. For emerging package types, this boundary between chip and package is becoming increasingly blurred.

First, we describe in detail the main unit assembly steps and the four main types of associated interconnect substrates (metal, ceramic, organic and new 3D substrates). This then enables us to describe the main types of package, including those dedicated primarily to wearable applications and the Internet of Things.

Next, the role of packaging in terms of thermal and electrical performance is highlighted. Although the main manufacturers carry out environmental tests, from the qualification of a new component to the commercial phase, the conditions of customer use determine the overall reliability of the function. With the emergence of highly compact packages, second-level reliability, i.e. that corresponding to the package mounted on a printed circuit board, is a point to be taken into account right from the circuit design stage.

A glossary and a table of acronyms and symbols are provided at the end of the article.