Global Semiconductor Report
New Trends Impacting Electronics Assembly
Not only are the ubiquitous “smaller, cheaper, faster” drivers forever reshaping electronics, but the demand for multi-functionality and mobility is also fueling the convergence of the computer, telecommunications, and consumer markets. Computer games can now be linked to the Internet. Cellular phones can be used to purchase soft drinks and send e-mail. Bluetooth technology is making wireless data transfer possible for computer and consumer products. With all of these changes in the products themselves, we can expect to see modifications in their manufacturing requirements.
The increasing sophistication of electronics products is driving advances in a number of aspects of electronics assembly, from components and substrates to the materials and processes used in production. We can start to see new trends at the component level. The explosion of the wireless market and increasing demands for advanced functionality in cellular phones have led to a steady rise in the number of components per phone within the same small space. Due to the throughput and yield constraints these requirements place on cellular phone manufacturers, we are experiencing a resurgence of multi-chip modules.
Because multi-chip modules can be pre-assembled and tested, performance issues affecting yield are typically resolved prior to production of the final product. Additionally, if a performance issue does arise with a multi-chip module, the module can be removed from the circuit and replaced without sacrificing the other components on the circuit board.
In turn, the growing volumes of multi-chip modules are driving the need for much smaller (less than 1 mm) and thinner (less than 0.1 mm) dies as well as smaller capacitors (0201). At the other end of the spectrum, microprocessors and high-end Asics are pushing die sizes above 400 square millimeters and pin counts above 2000 I/O’s. Wafer sizes are scheduled to migrate to 300mm, which will significantly impact all semiconductor-related equipment.
On the substrate side of the package, new challenges arise as the demand for advanced packaging and high density rigid and flex substrates increases. Challenges associated with manipulating and imaging these novel carriers and ensuring accurate placement of fine pitch components, which can be compromised by solder mask registrations, are driving changes in equipment handling, illumination (see figure 1) and vision systems.
Regarding process, flip chip and wafer level packaging present requirements for new fluxes, new underfills, and flux and underfill combinations with some level of particle fillers and new conductive adhesives. This translates into dispensing, vision and placement challenges for the assembly equipment. Additionally, the regulatory push in Asia and Europe to eliminate lead will force the use of more lead free solders, whose higher reflow temperatures place more pressure on substrate materials and component reliability. The drive to eliminate lead will also increase the use of conductive adhesives that require higher pressure and temperature during placement, greatly impacting machine throughput.
In light of these challenges, what is the ultimate package? Unfortunately, there is no ultimate package or silver bullet. Everyone has a favorite BGA, CSP, and WLCSP “du jour” from different suppliers. Today’s applications require different permutations of materials and processes, leading to a multiplicity of packages and form factors. The traditional boundaries between component (first level packaging) and card assembly (second-level packaging) have all but disappeared.
To handle a myriad of different substrates and new process materials, placement equipment is facing new requirements for increased flexibility and more sophisticated vision systems and lighting schemes. To keep up with the volatility of the market, electronics manufacturers are looking to partner with suppliers that provide both placement equipment and process solutions for state-of-art assemblies, global supply capabilities and best-of-breed cost of ownership.
Richard Boulanger is Vice President of the Advanced Semiconductor Assembly Division of Universal Instruments Corporation. This business unit focuses on bare die and flip chip applications such as plastic and ceramic ball grid arrays, flip chip on flexible circuits and hybrid assemblies.
[CAPTION, for figure 1, attached “BlueLight.jpg”]: New approaches to illumination are improving vision clarity and increasing placement accuracy on advanced substrates such as flexible circuits.