A New Level of Connectivity- 5G Package Considerations
Authors: Gerber Mark , Chang Harrison , Lu Wayne , Kao Gavin , Cho Jonathan , Hwang Roger 
Published: January 2025

Understanding the intricacies of 5G and the various technology challenges leave most people confused especially when RF frequency spectrum is brought into the discussion. We hear today more and more about faster internet speeds as the key benefit but what does this really mean to most people and how will this really be different than 4G? For most, just downloading a video or meme may be good enough, so how will this next generation of 5G really impact our lives? A good way to understand the 5G revolution is by looking at a similarity to what is happening with artificial intelligence (AI). Prior to Deep Learning, most AI methods were not able to produce the results that could exceed the human error rate, but around 2015, this changed. Deep Learning leverages what is called a “neural network” or basically a system of nodes that perform calculations but more in a parallel format vs a serial approach. The evolution of Wide IO memory has helped to enable this neural network type approach of computing by storing the outputs of these calculations into a parallel node like format. 5G is like deep learning in that mMIMO (Massive Multiple in Multiple Out) essentially creates a parallel or array approach to RF signals when communicating from towers which allow for many more device connections. Fundamentally, this larger number of connections can help prevent reduced data rates due to traffic and can allow multiple paths for data transfer. Setting data transfer speed aside, the ability for more devices to be connected reliabily and even using each other for connections as well begins to bring a true cross-linked network that has not existed. The ability to handle many connections and even segment the type of connections depending on application space, begins to paint the picture of the future to come. To enable these new technical approaches requires some new thinking for IC Packaging as well. To understand the various RF frequencies, you need to understand how certain frequencies are being used today. When you think about AM/FM radio, these are in the Kilohertz/Megahertz ranges and generally their signals travel far- usually 10s to 100s of miles. Cellular phone technology starting with 1G, 2G, 3G are in the Mhz to GHz and generally the higher the frequency, the higher the data rates. The challenge is that as you move up in frequency, the signal does not travel as far due to the energy being absorbed into materials. For Sub6Ghz, this is not a problem but at higher mmwave Ghz ranges, it can be real challenge when the signal is being used for data transfer and not just a proximity sensor like what is being used in automotive. For frequencies at 20Gh and higher, these signals tend to get absorbed in solid materials such as walls and thus a direct line of sight is required for a reliable signal. This can pose major challenges when trying to roll out a full network to support 5G and would also require a lot of towers to support due to the short effective signal distance for a good signal strength (around 1000 ft or less). For dense central business districts or on commuter trains this may be ok but wide area rollout continues to be difficult. The IC Packaging challenges are even greater at these higher mmwave frequencies due to the material sensitivities to handle these very fast speeds. For a signal to travel at these speeds, they travel on the outside of the copper trace (Skin) and minor roughness of these traces can initiate a skin effect that causes signal loss. The package design considerations for Sub 6Ghz are very different than for mmWave frequencies and require a different approach. Today, most of the world has focused initially on the sub 6Ghz frequency spectrum to roll out their 5G networks. This is primarily due to the similar RF considerations for infrastructure, handsets and other devices when moving from 4G/LTE. The key benefit that keeps the industry working on mmWave is the much-improved speed and low latency that it will provide. These challenges will take time to resolve and research in new materials, new process techniques, tighter tolerance process requirements, true 3D interaction impacts, and other considerations will be required to create a successful solution. The complexity of mmWave has driven several unique packaging solutions, one disadvantage to not having any design/package related standards in place. Which package solutions will end up winning in this higher frequency area remains to be seen but RF test at the device level and the integrated final product level will be critical for validating their performance. This presentation will step through a background on the 5G market and will also dive a little deeper into both Sub6Ghz packaging solutions as well as mmWave considerations.