Enhance Larger FCBGA Package Evaluation and Characterization

In this study, Cu pillar bump is firstly built on FCCSP with 65 nm low k chip. 7 DOE cells are designed to evaluate the effects of Cu pillar height, Cu pillar diameter, PI opening size and PI material on package reliability performance. No obvious failure is found after package assembly and long-term reliability test. The packages are still in good shape even though the reliability test is expanded to 3x test durations With the experiences of Cu pillar bump on 65 nm low k chip, Cu pillar bump is again built on FCBGA package with 45 nm ELK chip. White bump defect is found after chip bond via CSAM inspection, failure analysis shows that the white bump phenomenon is due to crack occurs inside ELK layer. A local heating bond tool (thermal compression bond) is used to improve ELK crack, test results illustrate ELK crack still exists, however the failure rate reduces from original 30%~50% to 5%~20%. Simulation analysis is conducted to study the effect of PI opening size and UBM size on stress concentration at ELK layer. Small PI opening size can reduce stress distribution at ELK layer. On the contrary, relatively large PI opening size and large UBM size also show positive effect on ELK crack. Assembly process and reliability test are conducted again to validate simulation results, experiment data is consistent with simulation result.

Are the fields of fracture mechanics, rheology, etc. good enough to address issues In package reliability? No: JEDEC specs all based on DIP wirebond packages. Are we using results from these fields enough or most effectively? Not addressed. Biggest difference with wafer reliability is stressors on chip are local (E-field, temperature), which stressors in a package are mechanical stress, which is resultant of the entire package materials' CTE.

Wide band gap semiconductors such as GaN possess many favorable properties comparing to Si, which make them especially suitable for high power and high temperature applications. This brings about unique opportunities and challenges for the development of robust and reliable packaging technologies. In this talk, we will focus on the thermo-mechanical aspects of packaging reliability challenges, where thermal stress can be a main reason causing failure of power modules. We will discuss the source of the thermal stress from materials interaction during temperature excursion, and will discuss some of the stress induced failure mechanisms such as delamination and fatigue. Characterization techniques for high resolution and in situ measurement will also be reviewed. We will point out the similarity and unique challenges of these problems as compared with Si based devices to show that packaging reliability of wide band gap semiconductor devices presents an exciting opportunity to explore new packaging materials and designs.

The semiconductor manufacturing is one of the most sophisticated processes in modern industries. It contains hundreds of complex operations, and this makes semiconductor reliability a challenging task especially in recent years that integrated circuits (ICs) have been broadly used at much wider areas including the health cares, automotive, and aerospace applications, where safety is the major concern. To make things worse, due to the shorter product life cycles and severe competitions, time-consuming reliability tests become unacceptable. The industries are in urgent need of a fast and effective way to quickly assess reliability risks. Under all these stringent limitations and the high reliability targets, we propose a consolidated approach that consists of an efficient and effective reliability baseline (BL) management system and a test scheme developed based on sequential probability ratio test (SPRT). To ensure a trustworthy setting for the SPRT test scheme, we apply the Bayesian approach to continuously update the BL database. An integrated flow chart is introduced to elucidate our proposed methodology. It is the first time SPRT is applied on reliability risk assessments with two unknown parameters. Several actual cases from semiconductor arena are reported to demonstrate the merits and powers of our proposed methodology. From these real cases, as a side benefit, we show the wide applicability of our method, which does not limit to reliability but on yield and functionality checks as well. To facilitate the use of our method by field practitioners, we do the best to explain derivations in a plain manner and provide analysis codes in R (in Supplementary Material) to make our approach as portable as possible.

This paper presents a comprehensive study on the reliability of QFN components for aerospace applications, particularly the impact of conformal coatings on the reliability of such QFN assemblies was investigated. Both experimental and computational modeling techniques are discussed. In the experiments, several types of plastic and ceramic QFNs assemblies were subjected to accelerated thermal cycling test, the daisy chains were monitored continuously during the test and the solder joints failures were recorded automatically with the cycle number at time of failure. Finite element models were developed for each type QFN assembly and the inelastic strain energy density was used as an indicator of the damage induced in solder joints under the applied thermal cycling load. Using simulation predicted damage together with the experimentally measured lifetime has provided the opportunity to develop a new physics-of-failure life prediction model for the second level solder interconnects in these QFN packages. The impact of conformal coatings on the reliability of QFN assemblies was revealed through comparing the results of non-coated assemblies with conformal coating coated assemblies. It was found that using coatings did not always increase the damage in the solder joint, the magnitude of the impact is dependent on the package size and the coating properties. Parametric analysis reveals that parameters such as die area and CTE of molding compound have less impact on the solder joint reliability when conformal coating is used.

Additive Manufacturing (AM) has revolutionized industries by enabling the production of complex, customized products with unparalleled efficiency. However, the increasing reliance on AM in critical sectors such as aerospace, healthcare, and defense has exposed it to significant cybersecurity and reliability challenges, including intellectual property theft, process sabotage, and data tampering. These vulnerabilities as well as reliability issues can compromise product integrity, safety, and operational continuity, posing severe risks to both industry and national security. In this work, we propose a novel methodology for modeling the AM process chain as a Cyber-Physical System (CPS) using multi-modal data structured in a graph format. Our methodology leverages Graph Neural Networks (GNNs) to detect and localize anomalies across diverse data modalities, enabling precise identification of both the nature and source of attack/fault. By integrating data fusion, advanced anomaly classification, and localization techniques, our solution provides a robust methodology for enhancing the security and reliability of AM processes, ensuring their safe deployment in critical applications. Furthermore, the proposed technique is adaptable to other industrial systems, underscoring its potential for broader impact in securing critical infrastructure.

Spin Transfer Torque Magnetic RAM (STT-MRAM) is one of the most promising on-chip technologies, which delivers high density, non-volatility, and near-zero leakage power. However, Spin Transfer Torque Magnetic RAM (STT-MRAM) suffers from three reliability issues, namely, read disturbance, write failure, and retention failure, that present significant challenges to its use as a reliable on-chip memory. All of these three reliability challenges become even more threatening with any increase in STT-MRAM cell temperature. Write operations are regarded as the main source of heat generation and temperature increase in STT-MRAM on-chip memories. This article first presents experiments to show how the heat generated by consecutive writes affects the reliability of an STT-MRAM on-chip cache. Then, it proposes the WiSE framework, an approach to reduce the STT-MRAM-based cache memory temperature and improve its reliability. WiSE utilizes the Reinforcement Learning (Reinforcement Learning (RL)) technique to detect high-density write operation patterns in STT-MRAM cache. To manage the write operations across the STT-MRAM caches, WiSE introduces a new temperature-aware replacement policy. The simulation results show that while WiSE imposes only about 1% performance overhead, it improves retention failure rate, read disturbance rate and write failure rate by 64%, 57%, and 47%, respectively, compared to Least Recently Used (Least Recently Used (LRU)) replacement policy.

Fatigue life evaluation of wire bonds in LED packages using numerical analysis

To provide the benefits of higher I/O density, smaller feature size, and better electrical performance, a full-array 1.0-mm pitch BGA package family were developed. Three package options, termed A, B and C, were investigated. Each of these options has its own advantages and disadvantages. The moire interferometry technique was used to measure the effective coefficient of thermal expansion (CTE) of these three options. To more efficiently access package reliability, a three-dimensional nonlinear finite element method was established. This method has shown good accuracy in predicting solder joint reliability. Using this method, various factors were studied, including die size, package size, package pad opening size, board pad size, solder ball size, die attach thickness, pad design, substrate thickness and board thickness. These studies have given us a good understanding of the effect of each factor and directions for improving solder joint reliability. The optimum parameter settings were selected for the packages. Finite element modeling was used to determine solder joint reliability of the three package options versus die size and package size. Thus, a roadmap of solder joint reliability vs. substrate technology, die size and package size was established. From this roadmap, a preset reliability goal can always be achieved by choosing the right combination of substrate, die and package size.

PurposeIn today's electronic package development cycle, activities are managed by multiple participants in the supply chain, which might have different quality and reliability impacts to the end product. As a result, the reliability risk is much higher for companies who do not have insight into and/or control over the products received. The purpose of this paper is to show how design‐for‐reliability (DFR) approaches will come into play to manage the risk.Design/methodology/approachIn this paper, DFR approaches for package development will be discussed from the perspective of the original equipment manufacturers (OEMs). DFR practices through the package development cycle will be described based on key development modules. A case study for flip chip ball gris array package development using an advanced Cu/Low‐k silicon technology will be presented. Key measures to help control the quality and improve the reliability will be presented.FindingsThe proposed methodology significantly improves component and package reliability through the engagement in design, manufacturing, assessment and system evaluation.Originality/valueThe paper discusses the research results and the proposed DFR methodology will be helpful for fabless design houses, electronics manufacturing service (EMS) partners in the supply chain, and OEMs to manage the reliability of the products.

Charge storage nonvolatile memory (NVM) is one of the main driving forces in the evolution of IT handheld devices. Technology scaling of charge storage NVM has always been the strategy to achieve higher density NVM with lower cost per bit in order to meet the persistent consumer demand for larger storage space. However, conventional technology scaling of charge storage NVM has run into many critical reliability challenges related to fundamental device characteristics. Therefore, further technology scaling has to be supplemented with novel approaches in order to surmount these reliability issues to achieve desired reliability performance. This paper is focused on reviewing critical research findings on major reliability challenges and technical solutions to mitigate technology scaling challenges of charge storage NVM. Most of these technical solutions are still in research phase while a few of them are more mature and ready for production phase. Three of the mature technical solutions will be reviewed in detail, that is, tunnel oxide top/bottom nitridation, nanocrystal, and phase change memory (PCM). Key advantages and reported reliability challenges of these approaches are thoroughly reviewed in this paper. This paper will serve as a good reference to understand the future trend of innovative technical solutions to overcome the reliability challenges of charge storage NVM due to technology scaling.

Robbani Snack was a micro, small, and medium enterprise (MSME) located in Gading Rejo District, Pringsewu Regency, Lampung. It was established in 2010 and operated in the snack food sector. At the time, Robbani Snack’s cassava chips experienced a decline in sales (slow-moving), and in some cases, they were sold close to their expiration dates. This condition indicated the need for an analysis of the importance and performance level of product attributes, as well as consumer satisfaction, in order to determine improvement priorities and enhance competitiveness. The study aimed to identify consumer characteristics, analyze the importance and performance levels, and assess consumer satisfaction with Robbani Snack's cassava chips product based on the 4P marketing mix (product, price, promotion, and place). This research employed descriptive analysis, Importance Performance Analysis (IPA), and Customer Satisfaction Index (CSI) to achieve its objectives. The results based on the IPA showed that the attributes in quadrant I (top priority) included uniformity of shape, packaging design, and ease of product availability. Attributes in quadrant II (maintain performance) included taste, crispiness, halal label, expiration date, price, and the location and convenience of purchase. Attributes in quadrant III (low priority) included flavor variants, color, packaging size, social media advertising, and specific discount offers, while quadrant IV (excessive) included thickness and discount offers during certain events. The Customer Satisfaction Index (CSI) calculation showed a consumer satisfaction level of 77.02%, indicating that the product had met consumer expectations. Keywords: Cassava chips, IPA, CSI

Next generation high speed network ASIC packages require perpetually larger and thinner packages to meet functionality and electrical performance requirements. Opportunities for highly integrated MCM’s and 2.5D/3D Si interposer packages are emerging to meet long-term performance needs, but for near-term, single chip ASIC applications, thinner packages utilizing thin substrates are an absolute requirement for the high end network market. Achieving both increased margins in the power delivery network and increased functionality in next generation 25/28GHz ASIC applications requires highly efficient (thin, minimal discontinuities, opportunities for enhanced decoupling), low loss package designs with package sizes up to 60x60mm. Coreless substrate based packages offer an excellent opportunity for low loss/low inductance package designs, but have consistently failed to be available at the necessary body sizes due to assembly and warpage concerns. The work presented in this paper describes key factors for mitigating warpage and identifies optimum processes, and materials for manufacturing large body size coreless substrate packages, especially for the high end network market. A test vehicle was developed using a 22x18mm^2, 40nm Daisy Chain die placed onto a 45x45mm^2, 8+1 coreless substrate with mixed pitch BGA footprint and BGA-side capacitors. Processes were developed to optimize assembly yield and package reliability. Key assembly materials were selected for optimum yield and high thermo-mechanical reliability. Substrate material stack-up and design were varied for further optimization and validation of thermal mechanical reliability models. As a result, critical factors impacting warpage were identified and modeling tools were refined to predict substrate. This paper describes the assembly processes, substrate BOM selection and design strategies adopted for mitigating warpage for coreless package sizes up to 45x45mm. Additionally, L1 thermal mechanical reliability results and key factors for establishing valid models will be discussed.

Security and reliability of cloud computing services remain among the dominant concerns inhibiting their pervasive adaptation. The distributed and the multi-tenancy nature of the cloud computing paradigm can be considered as the root causes for their increased risks and vulnerabilities. Resource sharing and virtualization can also be mentioned as additional main factors contributing to or augmenting cross-site scripting and other cloud vulnerabilities. Cloud are also exposed to the risks and liabilities faced by other networked systems. Poorly designed APIs that may cause security problems or distributed denial of services attacks are the examples of this category that are considered in this paper. Public key infrastructure provides the foundations for provision of some essential security services. These include services such as confidentiality, authentication, and privacy that are of vital importance for establishing trust and confidence between the cloud providers and their clients. In this work, we will discuss the potential flaws of this infrastructure and examine how they may deteriorate the security and reliability levels of the cloud environments. To enable a comprehensive study of the challenges in security and reliability of the cloud computing environments, we categorize the risks and vulnerabilities they face. Traditional techniques, based on cryptography, can address some of these challenges to a certain degree. We will argue that they may not be efficient for use in cloud environments. We then focus on data-centric and homomorphic encryption methods that may provide more appropriate solutions in addressing the challenges in cloud computing security and reliability.

In today's electronic package development cycle, activities are managed by multiple participants in the supply chain which might have different quality and reliability impacts to the end product. As a result, the reliability risk is much higher for companies who do not have insight into and/or control over the products received. Design-for-Reliability (DFR) approaches will come into play to manage the risk. In this article, DFR approaches for package development will be discussed from the perspective of the original equipment manufacturers (OEMs). DFR practices through the package development cycle will be described based on key development modules. A case study for FCBGA package development using an advanced Cu/Low-k silicon technology will be presented. Key measures to help control the quality and improve the reliability will be presented. The DFR methodology will be helpful for fabless design houses, electronics manufacturing service (EMS) partners in the supply chain, and OEMs to manage the reliability of the products.