Don’t Forget the Surface of Microelectronics

Pierce Geary

Image above: manufacture of chips on a silicon wafer under a microscope

 

It’s easy to be dazzled by the advancements in electronic and medical devices that are constantly being made and discovered allowing manufacturers to work on increasingly micro levels. Smaller tech means greater efficiency and higher production rates which can lead to lower prices and more accessibility. Tiny tech means less intrusion when incorporating electronics in everyday devices and medical applications. But we mustn’t let ourselves get distracted by all this progress. The surfaces of the electronic components of this incredible tech need to be clean at a chemical level in order to ensure that any bonding processes will be successful. It’s as true for these devices as for any others.

Electronics packaging, even at the micro and nano level, requires wire bonding processes and coating operations that involve smaller versions of the methods used on a larger scale. When working at such tiny levels the importance of how molecular level surface activity influences bond success and true chemical cleanliness becomes all the more evident.

Advancements in ultra-dense glass substrates are allowing for extreme leaps in production and quality of vanishingly small electronic components. Using laser-induced deep etching (LIDE) manufacturers can produce glass wafers with the capacity to connect more integrated circuits (or IC which are the chips found on a circuit board) than traditional circuit boards ever could. With evolution in production speed and ability, manufacturers need to keep in mind that processes to manufacture new technologies can introduce new contaminants.

Not only can your current process introduce surface contamination, but suppliers of emerging tech can change their own processes frequently as they innovate and cut costs. These frequent changes may create opportunities for contamination that weren’t present before. Knowing the condition of surfaces at a molecular level gives you the insight required to understand precisely how to prep the materials you’re getting from your suppliers.

When creating the packaging for these electronic components there is often wafer level glass to glass or glass to silicon direct interfacial bonding. Common bonding methods for this type of production are anodic bonding and fusion bonding. Many steps in wafer metallization and bonding processes include automated machinery, so incorporating an automated verification component to ensure proper surface cleanliness can ensure that the manufacturing process continues seamlessly and leads to a reliable device in the end.

Anodic bonding is a process where an electrical field is applied to the two surfaces at very high temperatures altering the chemical characteristics of the glass surface making it highly reactive and ready to bond. Fusion bonding similarly uses high temperatures as a curing or annealing step once the two surfaces have been chemically cleaned and forced together. Both of these methods rely upon the surfaces to have a SUPER clean surface and the EXACT chemical make-up necessary to ensure the success of the bond. Adding a step that guarantees the cleanliness and optimal chemical surface of the wafers can make all the difference in terms of adhesion success.

Reliability Engineers at electronics manufacturing companies have become obsessed with applying probabilistic models or PDfR (Probabilistic Design for Reliability) to be able to predict how bonds will fair in the real world. There has been a lot of energy devoted to failure-oriented accelerated testing (FOAT) which is a useful approach to predicting the strength of electronic packaging assemblies. It allows engineers to be able to anticipate solder joint connection failure based on these bonds being subjected to certain kinds of temperature cycles which can lead to things like solder creep, solder joint fatigue and parylene coating failure.

There is a major emphasis on predicting failure, however, BTG Labs is equipping electronics manufacturers with the insight they need to help prevent failure. Strengthening these bonds depends on optimizing the preparation of the surfaces coming together. Silicon is a necessary component of nearly all electronics and is also a massive detriment to bonds if not dealt with properly. When high-reliability is essential, manufacturers can’t take chances with their bonds.

Contact BTG Labs using the form below to get information about uncovering your Critical Control Points - any step that has even a minute affect on any bonding, coating, cleaning or printing operation, in your manufacturing process.

Our Surface Experts are ready to help you optimize your process so you’ll be ready for any changes in the ever-evolving electronics industry.

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