Surface mount technology (SMT) is one key factor leading to the shrinking of electronics systems. In India, this trend has been driven by the use of surface mount devices (SMD) in either products developed indigenously by Indian companies, or in those that have been outsourced to Indian EMS firms by global electronics leaders and original equipment manufacturers (OEMs).
By Ankan Mitra
Thursday, February 23, 2012: Electronics packaging is an evolving field, and with the shrinking size of products, component packaging has shrunk as well. The use of SMT in electronics manufacturing is evolving in India and leading to technological advances in manufacturing processes, as well as in the market for components, tools and equipment and soldering materials.
Changes in the PCB world
Due to the condensed component structure, the component fan-out has increased multi-fold. To cater to this increased fan-out, printed circuit boards (PCBs) have moved from the conventional two sided board designs to multilayer variants, with many manufacturers choosing high density interconnect (HDI) methods for their designs.
Though SMD component manufacturing in India is not yet in line with global trends, some manufacturing is taking place. The majority of the components used for PCB manufacturing are still sourced from abroad. However, the interconnect structure and PCB fabrication in India are quite closely aligned with global trends. A few PCB fabrication firms in India are capable of fabricating advanced level boards using HDI techniques. Most of the globally accepted low loss laminate materials are available in India for PCBs. Various metallic and organic surface finishes are also available. The cumulative result is advanced PCBs catering to both leaded and lead-free processes.
The areas of growth for PCB manufacturing include flexible PCBs, metal clad PCBs and PCBs with embedded discretes. Flexible PCB manufacturing that has 2D flexural capability has been widely adopted in India, though 3D flexural capability is yet to catch up. Metal clad PCBs manufactured in India are being widely used for LED applications, helping meet mechanical design constraints. PCBs manufactured by Indian OEMs with various embedded components are at the prototype qualification stages. For consumer electronics, in particular, these PCBs are set to be widely used in the next few quarters.
Though there has been commendable progress within the field of PCB manufacturing, this segment is still at a nascent stage in India. The use of the latest technology still remains within the confines of very few Indian and global PCB fabrication houses that have their manufacturing setups in India. The majority of PCB fabrication firms still lag behind, and need to have a clearer understanding of international standards and customer expectations. This is a major reason for the high cost of the boards fabricated in India, resulting in a high dependence on imported PCBs.
Specialised engineering services offered
Unlike PCB fabrication, electronics manufacturing is closely synchronised with global trends. A key driver in this segment is the setting up of facilities by global consumer electronics giants in India.
The push to Indian R&D companies to source boards from within the country provides enough of a challenge for the Indian EMS companies. Further, the outsourcing strategy of global giants has helped replicate the global best practices in manufacturing processes. Component packages like 0402 are commonly used to increase package-on-package (PoP) density. Also, larger BGA packages with a pitch less than 0.5 mm and dimensions up to 60 mm on the sides are being used for system-on-chips and application specific integrated
RF coaxial connectors in SMT
circuits. These packages present the challenge of higher manufacturing process yields to meet the yield fall-out of these components.
In addition, an emerging trend in India is to offer specialised engineering services as part of the introduction of the PCB assembly on the manufacturing floor. With EMS companies identifying many shortcomings in the OEM design in the post-manufacturing stage, these engineering services are now being introduced. EMS companies look into the OEM design, and highlight the possible additional tooling expenses due to the violation of the design rule checklist that is drawn-up based on their capabilities.
Advances in solder materials
SMT is also driving advances in solder materials, as the requirements for fine pitch printing and reliable solder joints with minimal solder volume have become a challenge. Smelting houses in India have been the main source of raw solder materials for a long time.
With leading global solder consumable manufacturers sourcing raw materials from India, the manufacturing processes for smelting houses now meet global standards. Also, a few global solder consumable manufacturers have set up offices in India offering high quality support, which, in turn, has raised the support requirements from Indian solder material manufacturers. This finally benefits the customers, specifically the EMS companies that normally interact with more than one supplier.
Specialised engineering services for SMT
Halogen free requirements have led to the emergence of new areas of work. With this as a regulation, the challenges faced by the EMS companies in India are very similar to those faced globally.
Flux is now available in various forms—liquid, paste or solid—and with various corrosion levels. This has significantly helped in soldering components of various types, which have different flux requirements within the same board, or which require more than one type of solder. One good example is customised components with castellation and a thermal pad at the bottom. In this case, flux in paste form is used as part of the solder paste and additional solid flux is used in castellation.
PCB surface finishes and chemicals used also greatly influence the direction in which SMT evolves. OEMs and PCB fabricators are moving away from the metallic (hot air solder levelling) and electroplated finishes (electroless nickel immersion gold and electroless nickel electroless palladium immersion gold) towards organic finishes (organic solderabilty preservatives or OSP).
The major challenges with the organic surface finish are the fidelity of contact during testing of the PCB assembly and the traces of OSP left behind. Advances in this area with conductive solder finishes (which is under qualification with a few Indian PCB fabricators) will help mitigate this challenge and streamline the use of organic surface finishes.
Various research projects for SMT are being undertaken by Indian academic institutions in partnership with industry. The primary focus is on alternative lead free solder alloys with soldering profiles similar to the legacy Sn63/Pb37 (tin-lead) alloy and also alternative to the widely used SAC (An-Ag-Cu) alloys. Another primary research area is the elimination of PCB surface finish defects in the wet process.
SMT equipment market
In India, most of the equipment used for electronics manufacturing, cleaning and inspection is imported. All the major equipment manufacturers either have a direct presence in India or have authorised dealers. Most equipment vendors excel in post-installation and annual maintenance support. With high speed electronics equipment and advanced soldering equipment available, advanced manufacturing using the Six Sigma approach that helps meet stringent standards is being done in India.
Rework equipment for advanced packages is another focus area. With several players working in the prototyping and rework segment, the use of precision rework equipment—both automated and manual—has increased significantly.
Automated board handling is another area of high growth. The subsidiary equipment used along with the main assembly equipment helps to increase manufacturing efficiency and process yields. With automated board handling equipment being used in the industry, process defects introduced due to manual handling—like wrong board orientation, ionic cleanliness requirements, etc—are almost eliminated.
Challenges faced by tooling vendors
Customised tooling has always been a requirement for electronics manufacturing. As miniaturised component usage increases manifold, new challenges are being faced by tool vendors. The first customised tool used in electronics manufacturing is the stencil. The IPC-7095 and different stencil design patterns and requirements are already known to stencil manufacturers in India. In addition, various types of step etched (level etched) stencils are now in use.
As more and more OEMs choose OSP as their preferred surface finish and move away from dual surface finish designs, additional solder deposition challenges are faced by stencil manufacturers—for example, requirements of less than 0.1016 mm (4 mil) of overall solder deposition to allow for both the EMI suppression effect as well as to meet the stringent mechanical constraints. As SMD component usage far surpasses the use of through-hole components, specialised stencil designs help use intrusive solder techniques as the preferred method for soldering through-hole components, thereby reducing manufacturing steps significantly.
PCB assemblies that use adhesives for SMD component assembly require specialised wave soldering pallets for soldering of component termination post-SMD assembly. Wave soldering pallets that meet world class standards are now available from Indian tool manufacturers.
With SMD density increasing manifold, the number of test points need to be reduced to meet the new shrinking real estate requirements. In-circuit testing (ICT) still remains the preferred test and programming option for PCB assemblies. Circuit test beds and fixtures development and manufacturing are the areas that need to scale up.
With various OEM service support centres based in India, rework fixtures like localised stencils and ball grid array (BGA) reballing fixtures have seen phenomenal growth. These, along with other specialised requirements, are available in India at quick turnaround times. Also, test fixtures for prototype requirements are readily available for those introducing new products.
Facilities being upgraded
Facilities that conform with ANSI/ESD S20.20 certification are a primary requirement for electronics manufacturing. With every EMS company and OEM seeking to establish electrostatic discharge (ESD) protection in its facilities, there is now the use of higher level segregation based on the ESD sensitivity of the components being handled. Also, within the same ESD protected area, smaller areas with specialised facility requirements are established to handle higher sensitivity components (like
Lead free manufacturing drives the requirement of different resources. Special requirements like nitrogen for high temperature lead-free assembly have now led to the need for new facilities.
Failure analysis labs coming up
The probability of device failure has increased substantially with the miniaturisation of SMDs. Also, failure analysis of failed devices has become a bigger challenge than ever before. The specialised equipment and skillsets required for the purpose are yet to become easily available in India.
Most of the failure analysis is done by the respective component vendors outside India. Fabless semiconductor companies in India outsource failure analysis to third party labs outside India. With more semiconductor companies coming up in India, a few such labs have opened their facilities within India. This has drastically reduced the turnaround time and enhanced correspondence within the engineering teams. This is a potential growth area supporting the electronics industry.
Need for standards
The growing demand for SMT in the electronics manufacturing segment in India has led to commitments from standardisation organisations like IPC, Electrostatic Discharge Association (ESDA) and Joint Electron Devices Engineering Council (JEDEC). IPC, with its office in India, has contributed significantly to awareness in the SMT domain through several international IPC training programmes. The most widely used assembly standard that covers IPC-A-610 E has been translated into Hindi.
As SMD packaging shrinks and stringent requirements need to be devised, ESDA and JEDEC are coming up with joint standards, which are being reviewed by committees from ESDA India. These activities help contribute to the acceptance of Indian products on the international market, and the incorporation of feedback encourages further progress and brainstorming in the developing areas.
Training in SMT now available
SMT training is available in India at different levels. Training in equipment installation, handling and operation, and facility setup is provided by the respective equipment vendor. However, operator level training for hands-on repair or rework and for inspection can be had within India.
Engineer and operator level training in India are now at par with internationally acceptable requirements, with IPC certifications available in the country. The training starts from the design, SMT process setup, process validation, assembly, repair, rework and inspection. Innovative ESD training programmes now cover design for manufacturing, design for assembly and design for testability. Programme management for EMS companies is also an area of development that is expected to grow in India.
However, most of the training is customer driven, specifically for contrast electronics manufacturing where the customer requirement drives the type of training. This is unlike OEMs, which have their manufacturing setups in India and impart internal training as and when new process requirements come up.
Product data management services
An electronic product involves multiple manufacturers in the supply chain at the system or sub-system levels—PCB fabrication, ASIC development and fabrication, PCB assembly, mechanical assembly and, finally, systems integration and software installation. Many times, these manufacturers refer to the product information specific to their deliverables. For example, the mechanical parts manufacturer who never gets to see PCB fabrication data like Gerber (a file format used by the PCB industry) may lack valuable information that could be critical to the end product’s quality.
Many Indian companies are now offering services in product data management. These services help to establish communication between the participating partners. The IPC-2581 standard developed by IPC and the International Electronics Manufacturing Initiative (iNEMI) is an xml based scheme representing an intelligent data file format, which is increasingly being looked into by OEMs based out of India. These OEMs also participate in the IPC-2581 consortium, helping to improve the standard from the point of view of Indian manufacturing.
Specialised services also being offered
With the increasing complexity of PCB assembly, specialised services are being provided by firms to OEMs and EMS companies. These include design for excellence (design for reliability, design for testability and design for Six Sigma) and product data management services.
Reliability study services are also provided by companies. These services test various parameters according to product requirements—like highly accelerated life tests for failures-in-time calculations, and high temperature operating life tests which help failure detection at different times of the product life (like at 100, 500 and 1000 hours). Other tests include solder heat resistance tests, electromagnetic interference/electromagnetic compatibility tests and ESD qualification tests as per IEC standards.
Third party certification services in line with these testing services are experiencing tremendous growth in India in various sectors like telecommunications, defence and healthcare. These tests and qualifications are mainly performed at the systems level, to verify the mechanical strength and various other parameters of SMD solder joints.
Specialised rework services for boards with surface mount components is an emerging trend and is applicable at different stages of the board’s lifecycle—prototype, production and field returns. These services include flip-chip components, package-on-package, inner-layer PCB laminate rework as well as the rework of embedded discrete SMD components in the PCB.
Consultants for manufacturing process defects troubleshooting are much sought after by Indian EMS companies. Design consultation for new SMD component packages, thermal management, and power rail design for multiple power rails on a board are also being sought by Indian OEMs. Besides these, consultation for the Six Sigma process and Japanese manufacturing methods like fool-proofing—in the form of Poka-Yoke and Kaizen (the continual improvement process)—is being encouraged by the National Productivity Council. Clusters of Indian EMS companies are being formed. Establishing benchmarks within each cluster helps improve manufacturing practices.
The way ahead
The use of SMT in electronics manufacturing is evolving. New services supporting SMT are helping to set new benchmarks and improve manufacturing practices. The lacunae identified within this segment will be filled over the years, driven by other sub-segments.
The author is lead for Surface Mount Technology Association (SMTA) India Chapter activities along with Rajeev Kulkarni. SMTA India Chapter is being formed out of Bengaluru and all set to start Chapter activities in 2012.
SMTA is an international network of professionals, who build skills, share practical experience and develop solutions in electronic assembly technologies, including microsystems, emerging technologies, and related business operations.
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