Oral Sessions


S16:Advanced and Green Materials and Process

Oct. 27, 2022 13:10 PM - 15:10 PM

Room: R503
Session chair: Vincent Wei, iCana Limited (Foxconn)/ Kuo-Chan Chiou, ITRI

2.3D Hybrid Substrate with Ajinomoto Build-Up Film for Heterogeneous Integration
發表編號:S16-1時間:13:10 - 13:40Pre-recording Video

Invited Speaker

Channing Yang, Manager, Unimicron Technology Corp.

• Introduction
• Heterogeneous Integration Package
• Test Chips and Wafer Bumping
• Build-up Package Substrate
• Fine Metal L/S RDL Substrate Fabrication
• Hybrid Substrate Assembly
• Summary

Novel Ni-free Surface Finish Next Generation PCB Technologies (RF-Microwave-5G-HDI-High Frequency) Focusing on Performance (Low Insertion Loss) & Better Reliability
發表編號:S16-2時間:13:40 - 13:55

Kunal Shah

The advent and ongoing evolution of internet-enabled mobile devices has continued to drive innovations in the manufacturing and design of technology capable of high-frequency/high-density electronic signal transfer. The combined requirements for both fast, always-on data transmission, and small geometric form-factors can be difficult to satisfy without compromised performance and signal loss.
Selection of materials used in PCB manufacturing is critical for optimum performance of the electronic assembly. Among the primary factors affecting the integrity of high frequency signals is the surface finish applied on PCB copper pads – a need commonly met by technology manufacturers through the electroless nickel immersion gold process, ENIG. However, a well-documented limitation of ENIG is its insertion loss due to the inferior conductivity of nickel over copper, leading to higher conductor losses. Additionally, nickel’s ferromagnetic properties adversely affect circuit performance. The result is an overall reduced performance in high-frequency data transfer rate for ENIG-applied electronics, compared to bare copper.
The selection criteria of surface finish for RF-MW, 5G, high frequency, high density applications, etc. (next generation PCB technologies) involves minimal insertion loss, long shelf life, cost-effective and high reliability. There are few options (EPIG, EPAG, DIG, etc.) available in the market and their pros and cons will be discussed. Moreover, an innovative nickel-less approach involving a proprietary nano-engineered barrier designed to coat copper contacts, finished with an outermost gold layer has shown superior benefits over contemporaries. Detailed insertion loss and reliability testing results will be discussed for the novel Ni-free surface finish.

Advanced PCB Lamination Material Development for High-Speed Networking Application
發表編號:S16-3時間:13:55 - 14:10

James Kenny, Yuki Hirokawa

Information technology is dramatically evolving. Ultra high speed application such as fifth-generation mobile communication system(5G) and wireless communication such as GPS and Bluetooth is getting more popular. In near the future, plenty of data traffic will be covered by them. In addition, we expect 6G and satellite communication will be developed and global standards to be set in near the future. We can expect Internet of Things(IoT) which all of devices are connected each other is coming soon. In the future, Internet of Everything(IoE) will also come to the world. At that time, the number of device and traffic speed will dramatically increase.
The Printed Circuit Board (PCB) are required to have high speed signal, be high-density capable and support high-layer counts. In addition, PCB is required to be environmentally friendly.
We introduce our approaches to achieve electronic properties required and to satisfy future application demand.

Integrated TaN thin film resistors with ceramic circuit board and improved the wrap angle of DPC ceramic sub-mount for Edge Emitting Laser applications
發表編號:S16-4時間:14:10 - 14:25

Eric Shen

Recently, the TaN thin film resistors, Edge Emitting Laser(EEL) has been rising for Direct Plating Copper (DPC) applications. In the past, to add resistors to ceramic circuit boards, it was necessary to mount the chip resistors on them through the SMT process.

In this paper, we have successfully integrated TaN thin film resistors with the ceramic substrate, which not only reduced the SMT process but also directly integrated circuits on the substrate. The TaN films were deposited by reactive magnetron sputtering. The electrode materials were prepared by Direct Plating Copper (DPC) from Tong Hsing(TH). First, the TaN films resistors were fabricated on the ceramic substrates with various surface roughness. We found that as the roughness of the substrate increased, the sheet resistance also increased for TaN films of the same size and thickness. Next, after the wet process of DPC, it is confirmed whether the roughness on the ceramic substrates and the sheet resistance of TaN have changed significantly. The results found no significant change. Finally, the difference in resistance value was observed by changing the process sequence of the resistance and the electrode. It was found that in the structure where the electrode was fabricated first and then TaN was sputtered, the resistance result was much greater than that in the structure where the electrode was fabricated by sputtering TaN first. The reason for this was speculated that there was an extra contact resistance resulting in an abnormally large resistance value. On the other hand, in the EEL process, the laser diode needs to be mounted on the ceramic substrate with the finished surface. The laser diode is installed on the boundary of the conductor surface, so the side wall of the finished surface needs to be close to vertical, so that the laser can be completely emitted. If the side wall of the conductor is not vertical, it will block part of the laser and cause the light to not be fully emitted. In this article, the process is improved to make the sidewall angle of the surface close to vertical.

A Fast Dried Coating Material which can Help to Pass ANSI/ISA G3 Corrosion Test for Protecting Outdoor Electronics
發表編號:S16-5時間:14:25 - 14:40

Dem Lee, Jeffrey Lee, Ricky Lee and Calvin Lee

The proliferation of Artificial Intelligence (AI), big data, 5G, electric vehicles, Internet of Things (IoT), edge computing, High Performance Computing (HPC) and Electric Vehicle (EV) in recent years has necessitated the increased use of electronics. Therefore, the hardware reliability of electronics has received more attention in the industry. With prevalent environmental pollution, air quality will also directly or indirectly influence the life of electronics in indoor and outdoor applications. In general, the hardware reliability of electronics can be easily affected by corrosive gases, moisture, salts, contaminants and particulate matter, especially in outdoor environments with high sulfur-bearing gaseous contamination. Therefore, next generation electronics required not only high performance but also robustness against harsher environments.
A guideline from the International Society for Automation (ISA) standard 71.04-2013 was used to classify the measured corrosion thickness of airborne contaminants into the various severity level rankings by using pure copper and silver coupon exposure. However, some end-customers have asked their Original Design Manufacturers (ODMs) provide the product for passing G2/G3 severity level compliant to 3 years, 5 years, even 10 years through accelerated corrosion methodologies in recent years. Therefore, more and more ODMs have adopted the conformal coating solution. Conformal coating is a popular solution which can protect the board and component to prevent the sulfur corrosion occurrence, especially in edge computing and outdoor infrastructure.
In this research, Flower of Sulfur (FoS) testing method was adopted to validate the anti-corrosion capability of bare copper Printed Circuit Board (PCB) with different conformal coating materials, including typical silicon-based and electronic grade fluorine-based conformal coating, and also benchmarked them against the bare copper PCB without conformal coating. Besides, this corrosion test can be satisfied ANSI/ISA G3 severity level compliant to 5 years exposure. Several analytical methods were used in this research, including, Optical Microscope (OM) Inspection, Coulometric Reduction (CR), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Finally, we found that fluorine-based conformal coating from 3M™ Novec™ has robust corrosion resistance that can enhance the specific protectively of outdoor electronics application.

Study on Interfacial Reactions and Tensile Properties in the Sn/C1990 HP Systems
發表編號:S16-6時間:14:40 - 14:55

Andromeda Dwi Laksono, Jing-Ting Chou, and Yee-wen Yen

Interfacial reaction is a fundamental issue for solder-joint reliability. Solder-joint reliability is influenced by the properties of intermetallic compound (IMC) layers. The mechanical characteristics of solder joints are primary problems in developing electronic packaging, and choosing the right metallization is critical for obtaining dependable solder connections. The Cu-3.28wt.% Ti alloy is named as C1990HP and has good conductivity and mechanical strength. It is suitable to be used as the lead-frame materials. The Sn is the base material for lead-free solder. The interfacial reactions between the pure Sn solder and the C1990HP substrate were investigated by using the solid/liquid reaction couple technique. The C1990HP/Sn/C1990HP sandwich couples were reflowed at 240 to 270°C for 5 to 1200 minutes. Based on the composition analyses by energy dispersive spectrometer attached on scanning electron microscopy (SEM/EDS) and electron probe micro-analyzer (EPMA), the abnormal structure of the Cu6Sn5 phase and the precipitated Ti2Sn3 phase which spread to the molten Sn were found at the Sn/C1990HP interface. The X-ray diffraction (XRD) results were also used to confirm composition analyses. The Ti atoms were dissolved into the molten Sn solder and provided as the heterogeneous nucleation sites for the Cu6Sn5 phase. The Cu6Sn5 phase spalls gradually in most couples with raising time and temperature. The thickness of the IMCs was enhanced when the reaction time and temperature were increased. The total IMC thickness in the C1990HP/Sn/C1990HP sandwich couples can be described by the parabolic law. The IMC growth mechanism was diffusion-controlled. The growth rate constants were increased with the increase in the reaction temperature, and the value of the activation energy is 101 kJ/mole. Additionally, the tensile test was conducted by using the C1990HP/Sn/C1990HP sandwich couples to measure the mechanical strength of the solder joints. The tensile strength and fracture behaviors at 200°C for various aging times were investigated. The result revealed that the tensile strength decreased with the increase in the aging time. However, the tensile strength increased when the reflowing temperature was increased. The tensile strength was decreased due to the change of the failure surface from the solder/solder interface to solder/IMC interface. The ductile fracture mode of the solder-joint reflowed at 240°C was found. When the reflowing temperature was raised to 255°C, both brittle and ductile fracture modes were found. Furthermore, the fracture mode of the solder joint reflowed at 270°C was changed to a brittle type. In this study, the Ti contents in the Cu-based substrate enhanced both the quantity and the detachment of IMC at the interface during the reaction. The C1990HP/Sn/C1990HP interface had good was the ultimate tensile strength (UTS) bonding due to the dissociative strengthening effect of Cu6Sn5 particles. It revealed that the minor content of Ti in the substrate could improve the mechanical properties of the solder joints.

Effect of Surface Finish on the Antenna Performance at 76–81 GHz
發表編號:S16-7時間:14:55 - 15:10

Ying-Chih Chiang, Pei-Chia Hsu, Chun-Jou Yu, Cheng-Hsien Chou, and Cheng-En Ho

Millimeter wave (mm-wave) frequency band (76–81 GHz band) has received widespread attentions in the radar sensor applications as its high resolution, long range, and beam-steering radar characteristics. In the normal life use, the antenna performance might be gradually degraded by the oxidation of conducting materials (e.g., Cu) due to the poor adhesion of oxides to dielectric materials (i.e., substrate), and cause signal integrity problems with short or open circuit. The adoption of surface finish to Cu circuits enables to prevent circuits from oxidation, thereby improving signal integrity and bondability/solderability with electronic components. However, the surface finish coatings would dominate the electrical properties of Cu circuits, particularly in the high-frequency applications, due to the so-called “skin effect’’. The focus of this study is to probe into the effect of surface finish coatings on the antenna signal performance in the mm-wave frequency band.

In this study, the signal performance of antenna (including S-parameters, VSWR, gain, directivity and radiation efficiency) with different surface finishes at 76–81 GHz was investigated through the finite element analysis (FEA) method by using a 3D electromagnetic simulation software (ANSYS-HFSS). Additionally, experimental measurements were conducted by using a vector network analyzer (VNA) and anechoic chambers to characterize the influence of electrical properties arising from different surface finishes, so as to validate the FEA simulation.

The IG surface finish seems to be beneficial to ɛR of the antenna operating at 76–81 GHz. In contrast, a significant degradation of ɛR was caused with adoption of other surface finishes, especially for the ENIG and ENEPIG cases. The degradation can be attributed to poor electrical and magnetic properties of the Ni(P) coating. The results of the present study indicated that the surface finish played an important role on the antenna performance (radiation efficiency) and IG surface finish is beneficial to ɛR of the antenna operating at 76–81 GHz. Detailed analysis on the S-parameters, VSWR, gain, directivity and radiation efficiency in relation to the surface finish coating will be presented in this paper.


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