This paper presents assembly challenges of mixed area array technologies covering Very Thin ChipArray® Ball Grid Array (CVBGA) and its Land Grid Array version (CV-LGA), embedded Wafer Level Land Grid Array (eWLP-LGA), and Copper-Pillar Flip-Chip (CP-FC) die—all with daisy-chain patterns to enable thermal cycle reliability monitoring for solder-joint failure evaluation. Twenty-seven (27) PCBs were assembled with a large number of variables in the design of experiment (DOE) to address: (1) assembly of mixed die and die-size array, (2) the effect of daisy-chain patterns on top layer or second layer bymicrovia-in-pad connections, (3) the effect of underfilling on improving resistance to thermal cycling, (4) challenges of single--and double-sided assembly processes, and (5) the effect of double-sided assembly on thermal cycle reliability. Acceptable assemblies with and without underfill were subjected to thermal cycling between –40°C and 125°C for solder-joint reliability characterization and failure-mechanism assessments. The paper will present details of DOE assembly parameters with the status of thermal cycle evaluation.

KEY WORDS: ball grid array, BGA, chip array BGA, embedded wafer level package, eWLP, land grid array, LGA,

Board level reliability testing is becoming a requirement amongst users for acceptance of components and packages. Standard component level JEDEC tests are not sufficient to qualify a supplier, this must be accompanied with board level reliability data to ensure assembly and field reliability. The paper presents a summary of board level reliability test performed on RF packages, the assembly process controls and monitoring, mechanical and environmental reliability tests, understanding of failure modes and lessons learned.

In recent years there has been an increased demand for electronic products with high reliability solder alloys having improved performance in thermal cycle resistance for harsh working environments. Traditional thermal cycling tests have used 40°C to +125°C for automotive type applications. There has been an increased focus on increasing temperature cycling test range to a higher temperature to account for increased product temperatures in the field. The work discusses thermal cycling results from -40°C to +150°C for soldered QFN/BTC and chip components with lead-free Sn3.5Ag0.5Bi6In0.8Cu (SABIX) and Sn3Ag0.5Cu solder alloys and ageing results at 150°C.

Reliability tests were undertaken by Thermal Cycling (-40°C to +150°C, 3,000 cycles) and Shear Strength testing with analysis of the amount of solder joint micro-cracking during thermal cycling. Thermal ageing tests were also undertaken at 150°C for 32 days (768 hours) for soldered chip components with Shear Strength testing during the thermal ageing tests and microstructural analysis. Cross-sectional and EBSD (Electron Back Scattered Diffraction) analysis were also undertaken on as-received (Time zero) and thermally cycled soldered chip component boards.

Tests done with the no-clean lead-free high reliability alloy (Sn3.5Ag0.8Cu0.5Bi6In (SABIX)) paste included Printability, Viscosity, Wetting and Void Occurrence after reflow for Power Transistor/BTC, BGA and chip components and Electrical ECM reliability. The results of the work are reported.

Keywords: Thermal cycling, high reliability alloy, ageing, shear testing, cross-sectioning, lead-free

Advanced Packaging is one of the key growing segments with high adoption rates and strong technology advantages and offersa pathway moving forward to support industry roadmaps. Sputtered seed layers – replacing chemical seed layers – are opening up a whole new range of possibilities, thus both OEM and manufacturers of next generation IC Substrate and Substrate-like PCBs are implementing sputtered seed layer as an enabling technology for smaller and more precise structures and improved reliability. Integrating new materials into packages – such as glass core with Through Glass Via (TGV) – and developing the next generation of Chiplet-Packages are interesting challenges that lay ahead.

Processing substrates with high organic load requires distinct process capabilities and well aligned process steps. This paper explains the most important do’s and don'ts for vacuum processing of organic substrates and its impact on the final devices.

PCB (Printed Circuit Board) and CCL (Copper Clad Laminates) industries are facing environmental issues and cost reduction challenges. Consumable release sheets are an important aid for many demanding lamination processes of those industries. Today, the release sheet market is exclusively composed of plastic films which are not environmentally sustainable. In addition, standard plastic films become brittle and difficult to manipulate at temperatures above 200°C; a temperature often required for the PCB and CCL pressing processes. In close collaboration with various stakeholders of the value chain in this market the authors’ companies harnessed their combined expertise in natural fibers, the Genuine Vegetable Parchment Technology, lamination and prototyping to create a new kind of lamination processing aid that rises up to the sustainable challenges of the PCB and CCL pressing industry.

The objectives of this partnership were to create a disruptive innovation leading to a greener alternative to the standard plastic release films at a lower cost. Last, but not least, the goal of this study was to determine if the sustainable release sheet developed could replace the traditional plastic release film used during the lamination step without any compromise on the process and the PCB performance.

This technical paper will detail the different tests and methodologies developed to ensure the performance of the release aid for the pressing of highly technical PCB components; including pressure and temperature test qualification with several types of base materials in a vacuum press but also the final performance check with visual inspection and mandatory quality control of the final PCB.

Ultimately, each step of the IPC-Class II Rigid PCB production was evaluated and benchmarked to make sure the new release aid delivers the same protection and performance as the current PE release film.

Wireless wearable devices can continuously assess and communicate the condition of patients and are crucial components of digital mobile health platforms. General societal trends across the globe, including a shortage of centralized laboratory and medical facilities, aging populations with increasing incidence of infectious and chronic diseases, earlier diagnosis of diseases, personalized medicine, companion testing for pharmaceutical use, government initiatives and insurance acceptance, are all important factors behind the demand for reliable, low-cost, wireless, wearable health monitoring devices. Fortunately, technological building blocks for implementation of these devices have evolved to the point that we believe that such monitoring will progress into a fully mobile approach in the near future, enabling continuous monitoring across acute, ambulatory and home care. In the past decade, a number of wireless physiological monitoring devices have been developed and tested in various clinical settings and a few of them are at early stages of product release. Furthermore, in 2020, due to the unprecedented circumstances of the COVID-19 pandemic, numerous wearable devices were investigated for early infection detection and patient monitoring in hospital and nursing home settings. In spite of this tremendous potential and significant investments by both device developers and government agencies, broad adoption of wearable medical devices has not yet been fully realized. The barriers to broad adoption include device cost and performance challenges, ease of use, integration of devices within the remote care flow system as well as lack of robust reimbursement models. In this paper, we will discuss flexible hybrid electronic manufacturing opportunities and challenges to create low cost, high performance wireless sensor systems for vital signs monitoring. We will highlight the critical need and progress towards enabling the supply chain workflows that allow for sustainable manufacturing solutions at large volumes.

Keywords: Flexible hybrid electronics, continuous vital signs monitoring, on demand interstitial fluid monitoring

To demonstrate the benefits of flexible hybrid technology (FHE) and printed electronics the team of Lockheed Martin Rotary Missions Systems Owego (LMO), Lockheed Martin Space Systems Billerica (LMB) and SUNY Binghamton University (BU) have designed and demonstrated a security RFID tag that utilizes a passive (battery-less) UHF-RFID chip within an FHE structure that contains embedded hardware security features. These features consist of printed high-resistance metal/carbon traces located within the tag substrate that generate a digital identifier for each individual tag. The team utilized LM thin-film security stamp technology to fabricate a multi-layer sensor network and embed anti-tamper/anti-counterfeit features in the substrate that are interrogated during the RFID tag-reader communication. Data is encrypted and stored in the tag and used as key material for the authentication process. In addition, the tag uses an aerosol jet printed optical 2D-barcode matrix printed over the RFID tag such that an external dual-reader (RF and optical) is needed to extract data and then de-encrypt using a secure software algorithm. This report will focus on the overall design and development of the RFID tag, highlighting the benefits of printed and flexible hybrid technology. The RFID tags resistance to different tamper attack vectors (vulnerability assessment) along with proposed refinements will also be shared.

Real-time and in-situ monitoring of the air-quality of confined spaces is a life-saving technology for commercial and government maintenance workers and is conspicuously absent from the commercial market. Existing solutions are not easily worn in confined spaces, lack sensitivity to hazardous gasses, and/or are not intrinsically safe. In response to a particular need by Air Force and Commercial aircraft maintainers, NextFlex has developed wearable chemical sensors which fill this gap. The sensor device detects volatile organic compounds, ambient oxygen level, temperature, and relative humidity. This information is wirelessly transmitted via a printed Bluetooth antenna this so that the worker and their environment can be remotely monitored. Charging and firmware updates are both accomplished wirelessly in the field. The devices are currently fabricated using flexible hybrid electronics approaches including conductors printed onto flexible films via screen printing and off the shelf components placed via standard electronics industry pick-n-place processes. This sensor device is conformal to the wearer and should not interfere with work in confined spaces and is encapsulated with a rugged silicone for protection against liquid and dust ingress. The silicone is applied via a molding process which protects against liquid ingress while allowing air to reach the sensors. This presentation will discuss the design, prototyping, and scale-up efforts on the sensor platform. Special emphasis will be placed on lessons learned in the design and process build up. Intrinsic safety and cybersecurity certification efforts will also be discussed and how they have thus far influenced the design of these low-power wearable sensors.

The Connected Factory Exchange initiative enables the use of tools, machines, and computer software to monitor, improve, and produce reliable hardware. The concept of the Digital Twin is to connect and communicate with assembly machines to analyze data, and from the data analytics, adjust and control the process.

There are four basic types of digital twin applications. The first type is visual inspection where software takes the data to create, see, edit, and make changes to better optimize the process. The second type is computational by processing the data to find a solution. The third type is operational by using software to make real-time decisions as to how to control an operation. The fourth type is analytical by finding patterns in the data, which are associated to a particular outcome.

The Electrochemical Reliability of an electronic device can be impacted by flux and process residues that are accumulated during the assembly operation. The idea behind this research is the use of SMART test instruments that qualify and control process contamination to ensure that these devices will function when called upon in their end-use environment.

The purpose of the research is to perform Thermal-Humidity-Bias (SIR) and Specific Area Extraction Testing (SAET) process control testing. The idea is to pattern an Electrical Twin test coupon into the panel of production circuit boards. The Electrical Twin will be populated with components that are representative of the process that can leave behind flux or process residues that can cause a failure. SMART test instruments that are Digital Twin capable will be used to test the Electrical Twin test boards.

Technical Cleanliness, i.e., the quantification, control and mitigation of deleterious effects of foreign object debris (FOD), is a common challenge in engineering. In the context of electronic assemblies, FOD can cause deleterious effects related to manufacturing (e.g. mechanical obstruction during mating of connectors) as well as field performance (e.g. short circuits due to loose particles or reduced electrical clearances resulting in electrochemical migration failures). Drawings as well as specific standards thus often contain general requirements on cleanliness, stating essentially that assemblies shall be free of FOD in general or free of FOD exceeding a certain size. However, such a ‘zero/limited FOD’ approach is typically neither practical nor required in electronics manufacturing: FOD has various sources, ranging from environmental contamination on the shop floor to assembly components and materials, making an elimination of FOD on electronic assemblies a sheer impossibility. This paper provides the results of a thorough assessment of the state of the art of technical cleanliness in electronics manufacturing as well as assessments of cleaning methods including their capability limits. The various sources of FOD, as well as the statistically meaningful quantification of technical cleanliness by suitable analyses and metrics are discussed. The results indicate the existence of the so-called gap dilemma: If loose metallic particles capable of bridging non-common conductors on a given assembly would generally result in electrical failures, the modern world as we know it would come to a halt, as practically all electronics in the field do exhibit such particles. This gap dilemma is rationalized by introducing a risk assessment tool that can be used to calculate failures rates and to assess design changes and specification violations.