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With the development of technology, wireless and IoT devices are increasingly used from daily life to industry, placing demands on rapid and efficient manufacturing processes. This study demonstrates the fabrication of an IoT device using a roll-to-roll printing process, which could shorten the device fabrication time and reduce the cost of mass production. Here, the fabricated IoT device is designed to acquire data through the sensor, process the data, and communicate with end-user devices via Bluetooth communication. For fabrication, a four-layer circuit platform consisting of two conductive layers, an insulating layer including through holes, and a solder resist layer is directly printed using a roll-to-roll screen printing method. After the printing of the circuit platform, an additional layer of solder paste is printed to assemble the electrical components into the device, inspiring the fully roll-to-roll process for device fabrication. Successful IoT device deployment opens the chance to broaden the roll-to-roll fabrication process to other flexible and multilayer electronic applications.

Stencil printing using solder paste material is one of the challenging processes in semiconductor assembly manufacturing. During evaluation of a semiconductor device, off-centered ball issue was encountered. The study aimed to mitigate the off-centered ball issue at stencil printing process by exploring the effect of different solder paste materials. Both solder paste materials were cured using the same reflow condition. However, solder paste material 1 (S1) resulted to cold solder joints while material 2 (S2) showed cured solder paste characteristic. With S2 material used in stencil printing, the off-centered ball occurrence was eventually eliminated. For future works, the solder paste material and configuration could be used for devices with similar requirement.

In this study, the nanoporous copper (NPC) sheets were fabricated by dealloying Cu40Al60 precursor alloy in 1.45 mol/L dilute hydrochloric acid solution under water bath at 80 °C for 12 h. The NPC sheets had a typical homogeneous ligament-pore microstructure with the average pore size of 320 nm. The NPC sheet was sandwiched between two Cu substrates with Sn3.0Ag0.5Cu (SAC305) solder paste. The melted solder infiltrated the NPC sheets and reacted with the Cu ligaments rapidly. A Cu/Cu-Sn IMCs/Cu interconnection can be achieved after reflow at 240 °C for 10 min under a pressure of 5 MPa. The average shear strength of the bondlines was 37.68 MPa, and the maximum shear strength can reach up to 57.38 MPa. The average resistivity of the bondlines was measured to be 13.38 μΩ·cm. At last, the evolution of microstructure, Vickers hardness and shear strength of the bondlines during aging test at 200 °C for 15 days were characterized. The bondline can be fabricated at a low temperature but can service at a much higher temperature with a high re-melting point, which can provide a new die attach method for high temperature power device packaging.

The miniaturization and high functionalization of electronic devices are driving the micronization of electronic components. In order to effectively microjoin electronic components, it is necessary to micronize the particles used in the soldering paste. In this study, we utilized an ultrasonic irradiation method to produce fine metal particles, and examined the influence of ultrasonic irradiation on the solidification process of the soldering materials. Bismuth–indium (Bi–45wt.%In) solder melted in a high-boiling-point solvent was exposed to ultrasonic irradiation to form droplets. By irradiating these droplets with ultrasonic waves during solidification, the amount of BiIn2 in the solid solder composition increased, while that of Bi3In5 decreased. In addition, submicron-sized agglomerations consisting of numerous small particles (~ 30 nm in diameter) were detected in the solvent; the In content of these clusters was ≥ 70 wt.%. It is thought that the amount of Bi3In5 generated decreased due to cavitation during solid–liquid phase coexistence, which caused the liquid-phase components with high In concentrations to separate from the droplets.

The properties of Sn99Ag0.3Cu0.7 (SACX0307) solder alloy reinforced with ZnO nanoparticles were investigated. The primary ZnO particle sizes were 50, 100, and 200 nm. They were added to a solder paste at a ratio of 1.0 wt %. The wettability, the void formation, the mechanical strength, and the thermoelectric parameters of the composite solder alloys/joints were investigated. Furthermore, microstructural evaluations were performed using scanning electron and ion microscopy. ZnO nanoparticles decreased the composite solder alloys’ wettability, which yielded increased void formation. Nonetheless, the shear strength and the thermoelectric parameters of the composite solder alloy were the same as those of the SACX0307 reference. This could be explained by the refinement effects of ZnO ceramics both on the Sn grains and on the Ag3Sn and Cu6Sn5 intermetallic grains. This could compensate for the adverse impact of lower wettability. After improving the wettability, using more active fluxes, ZnO composite solder alloys are promising for high-power applications.

Durafuse™ LT paste was designed as an alternative low temperature solder targeting at enabling hierarchy design for portable devices with good temperature cycling and superior drop-shock performance. It is formulated with the mixed solder powder technology to allow the paste reflowable at around 200°C or above. Durafuse™ LT formed solder joints with a melting temperature above 189°C and a plateau type reflow profile was recommended. Impact of reflow profiles on both drop shock and temperature cycling performance was investigated. The drop number increased with increasing peak temperature up to 210°C, presumably due to an improved homogeneity of solder joint. It also increased with increasing plateau time at peak temperature for temperature below 210 °C. At 210 °C, the drop number decreased with increasing plateau time, presumably due to increasing IMC thickness at pad interface. Homogeneous solder joints were more resistant to drop failure than mixed alloy system, and could be attributed to better homogeneity for the former system. Regardless of reflow profile impact, Durafuse™ LT showed at least two-order-of-magnitude higher drop shock resistance than Bi-Sn-Ag solder. Using the optimized reflow profiles, Durafuse™ LT outperformed SAC305 in drop-shock test. For LGA with homogeneous solder joint, Durafuse™ LT exhibited a characteristic life about 2.5X of BiSn0.4Ag. For chip resistor reliability in TCT, no significant difference in reliability could be discerned when comparing ENIG with OPS. Durafuse™ LT was slightly lower in reliability than SAC305. Higher peak temperature resulted in a better reliability for Durafuse™ LT. The chip size appeared to be an insignificant factor.

Contents -- PREFACE -- ACKNOWLEDGMENTS -- INTRODUCTION -- CHAPTER-1 THE PRINTED WIRING BOARD (PWB) IN ELECTRONICS MANUFACTURING -- 1.1 INTRODUCTION -- 1.2 HISTORICAL PERSPECTIVE ON PRINTED WIRING BOARDS -- 1.3 DESIGN OF THE PRINTED WIRING BOARD FOR MANUFACTURING -- 1.4 SUBSTRATE MATERIALS FOR PRINTED WIRING BOARDS -- 1.5 PRINTED WIRING BOARD CONSTRUCTION FOR MANUFACTURING -- 1.6 ADVANCED PRINTED WIRING BOARD TECHNIQUES -- CHAPTER-2 SOLDER AND AUTOMATED SOLDERING PROCESSES -- 2.1 INTRODUCTION -- 2.2 AUTOMATED SOLDERING PROCESSES -- 2.3 SOLDER FLUXES -- 2.4 SOLDER PLATING PROCESSES -- 2.5 WAVE SOLDERING -- 2.6 SOLDER PASTE MATERIALS -- 2.7 SOLDER QUALITY -- 2.8 SOLDER AND MATERIALS STORAGE PRECAUTIONS -- 2.9 SOLDER PASTE AND ITS APPLICATION -- 2.10 SCREEN PRINTING -- 2.11 SOLDER REFLOW PROCESSES -- 2.12 SOLDER PROCESS YIELD -- 2.13 SOLDER TEST PROCEDURES -- 2.14 COST CONSIDERATIONS IN SOLDERING -- 2.15 DEFINITIONS FOR SOLDER PROCESSES -- 2.16 LIST OF VENDORS FOR SOLDER PROCESSES -- CHAPTER-3 AUTOMATED ASSEMBLY TECHNIQUES -- 3.1 INTRODUCTION -- 3.2 HISTORICAL PERSPECTIVE ON AUTOMATED ASSEMBLY -- 3.3 METRICS ANALYSIS -- 3.4 DESIGN FOR MANUFACTURABILITY AND TESTABILITY (DFM /T) -- 3.5 DESIGN FOR ASSEMBLY (DFA) -- 3.6 AUTOMATED ASSEMBLY MACHINES, GENERAL -- 3.7 COMPUTER-AIDED MANUFACTURING (CAM) -- 3.8 COMPUTER-INTEGRATED MANUFACTURING (CIM) -- 3.9 VIBRATORY BOWL FEEDERS -- 3.10 SCREWDRIVING AND RIVETING FEEDER RATES -- 3.11 TAPE-SEQUENCING MACHINE -- 3.12 AUTOMATIC INSERTION -- 3.13 ADHESIVE AND SEALANT DISPENSING -- 3.14 WELDING APPLICATIONS -- 3.15 ASSEMBLY PROCESS YIELDS -- CHAPTER-4 ESD (ELECTROSTATIC DISCHARGE) -- 4.1 OVERVIEW -- 4.2 THE TRIBOELECTRIC EFFECT -- 4.3 SAFETY CONSIDERATIONS IN GROUNDING SURFACES -- 4.4 THE COMPLETE WORKSTATION PROTECTED AGAINST ESD -- 4.5 PRODUCTION LINE TECHNIQUES TO PREVENT ESD -- 4.6 ELECTRICAL INDUCTION AND ESD IN MANUFACTURING -- 4.7 MEASUREMENT AND TEST TECHNIQUES -- 4.8 IONIZATION -- 4.9 CONTAMINATION -- 4.10 THE MECHANISM OF DAMAGE BY ESD -- 4.11 DESIGN CONSIDERATIONS IN PREVENTION OF ESD -- CHAPTER-5 BAR CODING AND OTHER MARKING SYSTEMS -- 5.1 INTRODUCTION -- 5.2 ELEMENTARY DESCRIPTION OF BAR CODES -- 5.3 BAR CODES IN MANUFACTURING AND TEST -- 5.4 SYSTEM CONSIDERATIONS FOR BAR CODING -- 5.5 SOFTWARE CONSIDERATIONS FOR BAR CODE SYSTEMS -- 5.6 MACHINE READABILITY AND LABELS -- 5.7 PRODUCTIVITY AND PRODUCTIVITY INCREASES USING BAR CODES -- 5.8 BAR CODE READING PARAMETERS -- 5.9 BAR CODE PRINTING -- 5.10 OPTICAL CHARACTER READING OR RECOGNITION (OCR) -- 5.11 MAGNETIC STRIPE TECHNOLOGY -- 5.12 RADIO FREQUENCY IDENTIFICATION (RFID) -- 5.13 HISTORIC MILESTONES IN BAR CODING -- 5.14 BAR CODE SCANNING EQUIPMENT -- 5.15 BAR CODING CASE HISTORIES -- 5.16 FUTURE APPLICATIONS OF BAR CODING -- 5.17 BAR CODE DESIGN -- CHAPTER-6 MANUFACTURING TEST -- 6.1 OVERVIEW -- 6.2 BASIC ELECTRICAL TESTING -- 6.3 PROCESS TESTING -- 6.4 HIGH DENSITY CIRCUIT TESTING -- 6.5 CONTACT VS. NONCONTACT TESTING -- 6.6 AUTOMATIC TEST EQUIPMENT (ATE) -- 6.7 TESTABILITY AND TEST ENGINEERING RESPONSIBILITIES -- 6.8 MANUFACTURING TEST STRATEGY OVERVIEW -- 6.9 TESTS AND TEST EQUIPMENT -- 6.10 DETAILED TEST STRATEGY -- 6.11 SPECIAL FORMS OF CIRCUIT PROBING -- 6.12 AUTOMATED BOARD HANDLING -- 6.13 BUILT-IN SELF TEST (BIST) -- 6.14 FORMS OF SELF TEST -- 6.15 AN EXAMPLE OF INTERNAL DIAGNOSTICS -- 6.16 AUTOMATED OPTICAL INSPECTION (AOI) SYSTEMS -- 6.17 OHMEGA LAYER TESTING -- 6.18 LIST OF BARE BOARD TEST VENDORS -- CHAPTER-7 COMPUTER-ASSISTED REPAIR -- 7.1 INTRODUCTION -- 7.2 MONITORING THE PASS-REJECT STATUS OF PARTS -- 7.3 CAR AND CIM -- 7.4 DIAGNOSIS AND REPAIR -- 7.5 COMMERCIAL CAR-RELATED SYSTEMS -- CHAPTER-8 NETWORKING FOR ELECTRONICS MANUFACTURING -- 8.1 INTRODUCTION -- 8.2 NETWORKING FOR MANUFACTURING -- 8.3 THE SYNERGY BETWEEN DfSIGN AND MANUFACTURING -- 8.4 NETWORK CONFIGURATIONS -- 8.5 NETWORK TRANSMISSION CONFIGURATIONS -- 8.6 NETWORKING STANDARDS AND PROTOCOLS -- 8.7 SYSTEM NETWORKING COSTS -- CHAPTER-9 SURFACE MOUNT TECHNOLOGY (SMT) AND TAPE AUTOMATED BONDING (TAB) -- 9.1 INTRODUCTION -- 9.2 SURFACE MOUNT INTERCONNECT -- 9.3 LEAD STRESS IN SMT -- 9.4 OPTICAL PATTERN REFERENCES: FIDUCIALS -- 9.5 DEVICE PLACEMENT (PICK-AND-PLACE) MACHINES -- 9.6 TEST CONSIDERATIONS FOR SMT -- 9.7 CLEANING OF SMT PWBS -- 9.8 SMT YIELD -- 9.9 TAPE AUTOMATED BONDING (TAB) INTERCONNECT -- 9.10 NOMENCLATURE AND TECHNIQUES UNIQUE TO TAB -- 9.11 BONDING PROCESSES FOR TAB -- 9.12 TEST CONSIDERATIONS FOR TAB -- 9.13 ENCAPSULATION FOR TAB -- 9.14 STANDARDS FOR TAB -- CHAPTER-10 ARTIFICIAL INTELLIGENCE AND EXPERT SYSTEMS IN MANUFACTURING -- 10.1 INTRODUCTION -- 10.2 DOMAINS OF ARTIFICIAL INTELLIGENCE -- 10.3 AI APPLICATIONS IN MANUFACTURING -- 10.4 SUMMARY -- CHAPTER-11 KAISHA AND ELECTRONICS MANUFACTURING -- 11.1 INTRODUCTION -- 11.2 KAISHA COMPETITIVE STRATEGY -- 11.3 JUST IN TIME (JIT) MANUFACTURING -- 11.4 KAISHA FINANCIAL STRUCTURE -- 11.5 SUMMARY -- CHAPTER-12 WAVES OF OPPORTUNITY -- 12.1 INTRODUCTION -- 12.2 WAVES OF OPPORTUNITY -- 12.3 DECLINING INDUSTRIES -- 12.4 FLEXIBILITY IS AN ASSET -- 12.5 TECHNOLOGY TRANSFER -- 12.6 SUMMARY -- APPENDIX A CONTAMINATION PROBLEMS OF PWBS DURING MANUFACTURING AND TEST -- APPENDIX B INTERMETALLIC FORMATION IN SOLDER PROCESSING -- APPENDIX C BACKGROUND ON SCREEN PRINTING: THICK-FILM CIRCUITS -- APPENDIX D LIST OF ABBREVIATIONS -- APPENDIX E LIST OF DEFINITIONS -- INDEX.

The trend of the electronics industry to miniaturize package design has caused the need to adopt BGA packages for a variety of applications. OEM microprocessors have conventionally used LGA designs press fitted into sockets for ease of reworkability. However, BGA packages, which have been widely used for surface mount (SMT) applications, face challenges when they are used in sockets. One of the major challenges faced is the formation of intermetallics between the bare solder ball and the gold paddle of the socket. To address these challenges, Georgia Tech is developing a universal solution for socketing and SMT applications by surface modification of solder spheres. In this new approach, the solder spheres have an outermost noble metal layer which prevents any damage to the BGA and doesn't react with the gold paddle, when placed in a socket. The surface coating would also collapse with the solder ball under specific conditions during reflow when used in SMT applications. This paper focuses on the process of attaching these modified solder spheres on the package and subsequent assembly of the package on the board. We evaluated high and low melting solder pastes to attach the coated spheres to the package. A major challenge observed was the wicking of the solder paste to the entire surface of the solder sphere during reflow. This was addressed by studying the wetting characteristics of the solder paste on different metal surfaces and controlling the volume of solder paste required. Optimization of solder paste volume was done to control wicking and at the same time, achieve a strong and stable joint. Microstructure of the solder joint was analyzed to determine its effect on the joint stability. It was found that the amount of wicking is a strong function of the composition of the solder paste, the reflow time, and the material in surface with which the solder paste is in contact with. This work advances the assembly requirements of socketable BGAs.

Solder pastes were formulated for reverse-offset printing using Sn-3.0Ag-0.5Cu alloy particles. Paste solderability was improved by increasing only a small amount of particle content without a change of flux amount in solder paste, which was affected by the improvement of paste printability. The electrical resistance of the printed solder bumps decreased from 6 MΩ to 0.05 mΩ as the particle content increased from 79 to 85 wt%. The shear strength of the printed solder bumps linearly increased from 46 to 61 MPa with the increase of particle content. Thermal and microstructural analysis revealed that the suppression of supercooling led to the growth of β-Sn aggregates surrounded by intermetallic compounds, which strengthened the mechanical properties.