Oral Sessions

Frequencies of 150 GHz and above will be used for ultra high speed data transmittion in future 6G applications and for radar detection. The electrical connection of HF chips in this frequency range is a major challenge for packaging technology. These include e.g. B. the signal propagation between a beamforming chip and power amplifiers in a MIMO antenna module (Multiple Input Multiple Output) or the connections between radar chips and antenna elements.
　　Embedding chips in a high-frequency printed circuit board combines very short connections with low signal losses with good scalability for low-cost mass production. A 39 GHz MIMO antenna module with a PCB-embedded beamforming chip will be shown as the result of a European funded project between industrial partners and Fraunhofer IZM. The manufacturing process and electrical characterization are presented. A 150 GHz antenna module with an embedded GaN power amplifier was realized in a strategic Fraunhofer project. Manufacturing processes and electrical properties are also shown here.
　　In addition to the classic methods of transmitting high-frequency signals using strip lines or coplanar waveguides, hollow waveguides can also be used. Air-filled waveguides in printed circuit boards can be realized with different technologies. The biggest challenge is the development and manufacture of structures for coupling electromagnetic waves from striplines to waveguides. In a German cooperation project, waveguides in printed circuit boards and coupling structures were realized and characterized up to 110 GHz. Future applications of micro waveguides for very high frequencies are discussed.

 

The Automotive industry has made big leap in advancement in the past 20 years with the introduction of hybrid and full EV vehicles; and more importantly the reduction in dependency of human intervention in driving thru implementation of driver assistance systems (ADAS) and autonomous driving (AD) technologies. These ADAS and AD rely solely on imaging camera to support applications such as pedestrian recognition, vehicle recognition, lane/junctions detection, traffic lights detection and driver fatigue detection in the cabin. All these features will help in keeping driving risk much lower and also helps our ageing society to continue to drive and be mobile.
These advancement have driven higher demand for image sensor packages that can meet the stringent automotive reliability. In this paper, we will present novel methods for packaging image sensor on laminate substrates and pushing the boundaries by increasing miniaturization to enable higher pixel counts towards technologies that enable higher image quality and functionality.
Studies in achieving a high assembly yield (especially in foreign particle control) and reliability will be presented. Top key challenges in qualifying this image sensors iBGA package and novel method to mitigate packaging risk will also be discussed.

 

The quality of redistribution layer (RDL) dominates the electrical performance of semiconductor package. Theoretically, the RDL thickness uniformity control becomes more challenge as increasing the substrate size, especially on the 600mm panel platform. In this study, the dummy pattern around and across the panel, called as firewall, have been used to influence the electrical distribution, to overcome the electroplating copper thickness uniformity problem around the blank area, which is used to develop the high-quality fan-out panel level packaging (FOPLP). The experiment results show the RDL thickness non-uniformity can be improved by 21% and 31% by tuning the area and the metal density of firewall, respectively. This firewall tuning technology is useful to diminish the RDL thickness difference among all dies within the panel, which can be adopted in any high-performance large size panel level packaging.

 

Majority of 5G NR can be grouped around one of three categories: Enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), of which eMBB brings the advantages of 5G to the general public as it can deliver higher data rates internet access in previously challenging conditions.
In past years, many applications, therefore, are in the scope of eMBB such as mobile communication, HD media, macro/small cell, fixed wireless access, and many more. One of the eMBB applications is AR/VR/MR (Augmented Reality/Virtual Reality/Mixed Reality) fields. These devices are able to create 3D images by stimulating the user’s visual and auditory senses in order to create a realistic and immersive experience for the user. The most important issues regarding wireless transmission are low latency, high stable coverage, and high data rate requirements. The best solution is using the 5G FR2 spectrum, which is mmWave bands (like 28GHz, 39GHz, etc.). These bands have a significantly lower latency, higher network capacity, and higher throughput, as a “last-mile” wireless communication solution providing a high-speed and high-reliability connection to personal and business.
On the other hand, the mmWave bands have a shorter transmission range, limited coverage area and are more susceptible to signal loss due to weather or objects. Therefore, highly directional beamforming and massive MIMO antennas have become vital in commercial wireless communication.
Furthermore, the wavelength of mmWave is from 1mm to 10mm in the air. Antenna process can be designed from PCB level to package level. As the result, the antennas and ICs can be further integrated into one package, which is Antenna-in-Package (AiP) technology. This further provides very compact size, higher performance, lower power consumption, and more cost effective mmWave products, which are ideal for the above mentioned AR/VR/MR devices.
In this work, we implement a 2x2 broadband dual-polarized antenna array using AiP techniques for 5G mmWave applications. This design has been simulated using ANSYS HFSS program and parameters of substrate which were based on the extraction work in previous study. A stacked structure is designed and manufactured on the 4+2+4 substrate process with size of 13 x 13mm. This paper has analyzed and optimized the stack up ratio of the driving patch to the stacking patch, and added parasitic elements to expand the bandwidth, thereby achieving broadband characteristics on thinner substrates. We have also studied the effect of process tolerances on the performances of this design. In addition, these Dk/Df parameters of prepreg layer and core layer where extracted by T-resonators and patch antennas, respectively. When we have known these real parameters, we can avoid getting the performance deviation of antenna design such as impedance mismatching, resonant frequency and bandwidth shifting, etc.
The results show that structure provides a broadband benefit to cover the all 28GHz mmWave bands (n257, n258, and n261) of 3GPP standard. Dual-polarized feature is also achieved by different feed-in ports in vertical plane and horizontal plane. Within the bandwidth, this structure can get a good isolation between the different port. Thus, the signal channels can be separated from each other and allow data to be transmitted through both channels operating on same frequency without interference. Such a 2x2 MIMO configuration is the simplest and most popular architecture in the mmWave bands. Moreover, this antenna array presents the beamforming feature for beam steering applications. The simulation results show different beam direction by controlling the phase of each antenna element. Finally, a 2x2 broadband dual-polarized AiP is being implemented on 4+2+4 low cost multilayer substrate to verify the simulation and measurement results and expected to gain an agreement performance for 5G mmWave beamforming systems.

 

Laser drilling is widely employed for PCB/FPCB production, especially for ABF/RDL substrates used for 5G telecommunication. Compared with the mechanical drilling which is usually used for the via diameter over 200um, laser drilling can fulfill the smaller via diameter amid 15um and 200um. Plasma descum and wet cleaning are the common post-processes after the laser drilling to obtain the better via quality by removing drilling residue and debris.
But traditional nano-second/pico-second lasers used in laser drilling may not drill well on the protective layer or redistribution layer(RDL) of the wafer-level chip-scale-package(WLCSP). Challenges including : (1) Bottom metal layer damaged or insulation layer peeling from the metal layer attributed to the severe heat-affected-zone(HAZ). (2) Via diameter smaller than 30um is unachievable. (3) Positional error below 5um can’t be secured while drilling at the faster speed.
This paper will demonstrate using the femto-second laser with the inherent feature of cold ablation to drill vias on the ABF layer and then carrying out the post-treatment of plasma descum to fulfill the requirements of higher taper angle and faster throughput. Advantages include : (1) Flesible drilling capability, via diameter is programmable in the range of 15um to 200um. (2) Undamaged and residue-free on the bottom metal layer. (3) Smooth via sidewall. (4) Continuous drilling can reach the speed of 3000 via/sec.

 

3D IC integration becomes one of the important trends in microelectronics manufacturing, and direct Cu bonding is considered an ideal way to achieve inter-chip vertical connections for TSV (through silicon via), due to size miniaturization and low electrical resistance. In this study, plasma was adopted to modified copper surface, and the effect of a subsequent light exposure was systematically investigated. Experimental results reveal that plasma bombardment contributed to a higher surface energy, especially those with H2-mixed gases. It also gave rise to compressive residual stress for copper surface, which led to an accelerated self-diffusion and improved bonding strength. With respect to plasma/flash combined treatment, only the N2-plasma samples showed enhanced bonding performance. For those treated with plasmas with H2 mixed gases, copper surface was highly activated and formed a thicker oxide layer which accounted for inferior bonding strength.