From the Apple Watch and body cameras for law enforcement to virtual reality hardware and autonomous transportation,the opportunities for electronics to improve our lives are limited only by our imaginations. The capability of existing PCB assembly technology needs to advance rapidly to meet the mission profile of these new devices. The demand common to all of these devices is increased functionality in a smaller space. For the solder paste manufacturer,this path inevitably leads to incorporating finer metal powder into solder paste to facilitate ultra-fine pitch printing. This study evaluates the benefits and implications of finer mesh solder powder on critical aspects of solder paste performance. Type 4,5 and 6 SAC305 solder pastes were tested and their characteristics in several key areas were measured and studied. The key input variables included powder size,effect of room temperature storage,pause time and PCB feature types. Output included print transfer efficiency,volume repeatability and performance stability over time. The goal of the study was to measure the benefits derived from smaller particle size and identify possible negative implications. With this information,assemblers and technical support personnel will better understand how to apply their resources to ensure the most robust process and optimized performance. The study was undertaken in two parts to measure both print characteristics and reflow characteristics. The print results are reported in this paper.

In the electronics industry,consumer demand drives a large portion of product innovations. Consumers want greater functionality and power,while maintaining a small footprint. Due to this demand,printed circuit board (PCB)manufacture and the related solder paste screen printing process become increasingly complex. Generally speaking,in high volume surface mount technology (SMT) assembly; consistent solder paste print volume and deposition are required to insure a high yield rate. With new product designs adopting finer pitch,smaller components,and greater density,stencil designs violating typical recommendations for area ratio are being evaluated. Using a stencil nearing or exceeding boundaries of known good performance challenges consistent screen print volumes and deposition throughout an entire PCB. This paper will review a solder paste developed for use with a combined solder paste inspection (SPI) and jetting tool. The paper will consider the viability of this process to prevent defects related to insufficient solder paste prints.

Water soluble lead-free solder paste is widely used in today’s SMT processes,but the industry is slowly moving away from water soluble solder pastes in favor of no-clean solder pastes. This shift in usage of solder paste is driven by an effort to eliminate the water wash process. Some components cannot tolerate water wash and elimination of water washing streamlines the SMT process. Despite this shift,certain applications lend themselves to the use of water soluble solder paste. High-reliability applications require removal of flux residues and it is much easier to remove water soluble flux residues than no-clean flux residues. Because of this reality,water soluble solder pastes will be used for the foreseeable future. Due to industry movement away from water soluble solder pastes,research and development resources have been focused on no-clean technologies. Some water soluble solder pastes in use today were developed many years ago,possibly before the era of lead-free soldering. Because of the prevailing trend toward no-clean formulation efforts,water soluble solder paste technology has fallen behind no-clean technology,especially for use with lead-free solder alloys. However in order to meet today’s requirements for certain applications,new high performance water soluble solder pastes are needed. This paper details the research and development of a new water soluble lead-free solder paste which improves on the performance characteristics of existing technologies. The key attributes of this solder paste are as follows:
• Environmentally stable in a wide range of conditions
• Long stencil life
• Excellent print characteristics
• Nominal wetting especially on hard to wet surfaces
• Very low solder balling and graping
• Easily removable flux residues
Challenging test methods were used to develop this solder paste and the results are detailed in this paper. Testing on this new water soluble solder paste is compared and contrasted to existing solder paste products. This development work created a new water soluble lead-free solder paste that meets the current and future needs of the industry.

As electronic assemblies continue to shrink in size,component population densities are increasing. Design engineers are forced to utilize all available board real estate and continuously push the limits of manufacturability. The next generation of board designs will incorporate even smaller passives than 01005 and tighter area array pitches than 0.3mm,while pushing design rules to reduce typical component spacing to less than 1mm. As limits are pushed,the need for advanced rework solutions is sure to increase from research organizations to volume manufacturing. This paper will address some of today’s most challenging rework applications and explore the demands of tomorrow including:
•Rework of 008004 micro passives
•LED rework as small as 0.5mm•Micro Sensor Rework
•Assembly of Delicate Beam Lead Diodes
•Flip chip
Specific challenges of reworking these applications will be identified and discussed,including process,material and equipment variables not common to 1mm plus rework.

Pb-free Ball Grid Arrays (BGA) present unacceptable reliability risks for defense and space programs,but what are the options when SnPb devices are no longer available? BGA manufacturers express concern over the additional reflow cycles necessary for the reballing process. In addition,traditional re-balling processes for SnPb components requiring rework do not accomplish the complete flush of the existing alloy necessary prior to attaching new spheres. However,there is evidence that BGAs,as a rule,are very robust. Furthermore,an imminent industry specification,IEC/TS 62647-4,Process Management for Avionics –Aerospace and Defense Electronic Systems Containing Lead-Free Solder –Part 4: Ball grid array (BGA) Re-balling,provides guidance necessary to successfully convert Pb-free spheres to SnPb without thermal or mechanical damage. An examination of one BGA part type,reballed up to ten times,provides a view of IEC/TS 62647-4 type guidance and testing as well as the impact of multiple reballing attempts on the BGA. Barring another available specification for reballing,this specification was used for structure in this study

Growing material regulations compel electronics manufacturers to rethink product compliance. Can a company state with confidence every substance in the final product has been identified,and from where each item was sourced,by all direct and indirect suppliers? Consider the impact of the REACH,RoHS and Conflict Minerals regulations on the electronics industry. REACH protects human health and the environment through early and accurate identification of intrinsic properties within chemical substances. Companies must report all potential hazards,and then implement risk management measures. RoHS impacts all electronics manufactured or imported into the E.U.,regardless of whether the manufacturer intended the item for sale in region. Conflict Minerals requires companies to validate the sourcing of tin,tungsten,tantalum and gold (3TG) in products is not tied to vicious armed conflict in Africa. Electronics companies are challenged to verify the source materials came from conflict-free smelters. Companies must explore the greater complexity that spans the entire supply chain,including direct and indirect suppliers. As an article producer,each company is ultimately responsible for everything contained in the product. Simultaneously,companies must respect intellectual property,data accuracy and public perception,all within the changing compliance landscape. The End-of-Life Vehicle (ELV) legislation in the 1990s required the automotive industry to begin addressing the topic of material compliance reporting two decades before most other industries. The current solution employs data exchange standard,laboratory analysis,and supplier data communications to create a set of solutions that has proven effective. The company has been a partner with Automotive in developing and sustaining the approach,and is actively working with companies in other global industries. Lessons learned are shared from the successes and failures of our predecessors and industry partners,to aid the industry as we proceed together in today's complex regulatory environment.

One of the biggest challenges a corporate environmental compliance team faces is to collect complete and accurate material and substance data in a timely manner from suppliers. This paper will provide insight into some of the complexities involved in the logistics of supply chain data collection for RoHS,REACH,and Conflict Minerals. The paper will try to uncover why supply chain data collection is such a difficult task and propose some solutions (such as using industry standards like IPC-1752A) that companies can employ to make the process a little easier.

In 2012,The European Directive on Reduction of Hazardous Substances was recast. The new version of the directive now requires products to be adequately validated as RoHS compliant in order to be eligible for CE marking and access to the EU market. Additionally,the recast also increased due diligence requirements for companies validating their products as compliant,including elevated documentation,data validation,risk analysis,and record keeping requirements. Methods used to address RoHS compliance before this change,such as simply collecting RoHS compliance statements from suppliers,may no longer be adequate. This paper starts by reviewing the evolution of the RoHS directive and how it has evolved. It then moves on to cover the requirements and scope of the directive,as well as which standards are used to demonstrate compliance,and how those standards must be referenced in internal company quality processes. Suggestions on best practices for building a comprehensive,efficient,and effective product environmental compliance process with a focus on risk mitigation and cost containment are provided,including real world examples. New specific requirements for classifying parts and materials according to risk will be addressed,as well as new requirements to rank all part and material suppliers by evaluating the trustworthiness of the data they provide. Marking requirements,declaration of conformity formatting and examples,and technical compliance files,will be covered with examples provided. The EU REACH law is also addressed briefly. Although the REACH law is not tied to the RoHS directive or CE-Marking,REACH validation is required for access to the EU market,and compliance validation techniques can be similar to RoHS compliance validation. References to standards and industry resources are provided.

With increasing popularity and momentum for wearable and printed electronics,stretchable printed ink has become a hot subject for study and application. Circuitry printed from stretchable ink remains conductive even when it is elongated at a high percentage,thus it is useful for many wearable applications where stretching is required. There have been limited studies on stretchable ink and its stretchability. The characteristics of the stretchable ink and how different factors impact its stretchability are not well studied and therefore unknown. To accommodate the increasing demand for wearable applications,it is necessary to perform evaluations on the stretchable ink. This paper presents the company studies on stretchable printed ink. A test coupon is designed to prevent instability of connection between test probe and printed ink pad. Different design and test parameters are evaluated to shed light on how they affect the stretchability. The study is very useful to not only optimize the ink stretchability,but also provide insight on how to improve ink chemistry to enable more stretchability.

The rules of the game in PCB production are changing with new disruptive technologies. At the company there has been the implementation of a “primary image inkjet-resist” printer for both inner-layer print and etch and outer layer pattern plating processes in full production. Inkjet printing has become a crucial building block for the first zero emission,fully automated PCB factory. Ink jetting resist eliminates standard lithography processes while still providing a fully digital solution in a very small footprint. This technology combined with an intelligent nozzle conditioning routine,and real-time ink channel acoustic monitoring with double channel redundancy,gives full process control during production. To ensure higher yields and continuous feedback,the print is also fully inline scanned by integrated AOI at full process speed to check the print result before etching (Image Quality Inspection). The fully automated panel logistics,the clean machine,and reduction of processes enables CAM to etch processing within minutes. The short overall process pipe line and digital imaging gives flexibility to the flow and facilitates easy mixing of jobs. With “jet-resist”,production becomes a straight forward process,greatly reducing process steps and complexity compared to traditional production. Furthermore,since the resist is based upon a hot melt wax,the use of next generation etching and stripping process techniques have been employed that have resulted in 100% closed loop rinsing,stripping,and etching processes that consume no chemicals,and require no waste treatment whatsoever. The only by-products are solid resist and pure copper metal,which may be reused in the copper plater. Additionally,the precision of the ink placement on the substrate,further allows for a 5-10% increase in panel utilization compared with standard dry film and liquid resist application processes. The overall solution represents the next generation in PCB Fabrication,and a formula for manufacturing in North America and Europe at equal to or lower cost than current Asia-Pacific sources,in much shorter cycle times.