DECEMBER 2011: Surface-mount technology (SMT) is one of the key factors for the shrinking electronics system-level packaging. The key drivers for SMT in India are the use of surface-mount devices (SMDs) in products developed indigenously by the Indian companies in the private as well as government sector, and the sourcing strategies of global electronics leaders and original equipment manufacturers (OEMs) to have their own manufacturing set-ups in India, or outsourcing the manufacturing to Indian or global contract electronic manufacturers (CEMs).

With the electronics packaging being an ever-evolving field, and the focus on shrinking the size and having more packaging capability within the same or lesser real estate, component packaging has shrunk as well. 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 boards to multi-layer boards, with many manufacturers choosing high-density interconnect (HDI) methods for their designs.

Electronics assembly
Electronics assembly

PCBs, components and systems
Though SMD components manufacturing in India is not in line with the global trends, some manufacturing is taking place. Majority of the components used for board manufacturing are still sourced from abroad.

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However, interconnect structure and PCB fabrication are moving quite closely with the global trends. A few PCB fabrication houses are capable of fabricating advance-level boards using HDI techniques. Most of the globally accepted low-loss laminate materials are available in India for the PCBs. Various metallic and organic surface finishes are also available. The cumulative result is advanced PCBs catering to both leaded and lead-free processes in India.

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 can be seen widely in India, though 3D flexural capability is yet to catch up. Metal-clad PCBs manufactured in India are widely being used for LED applications helping meet mechanical design constraints. PCBs by Indian OEMs with various embedded components are under prototype qualification stages. Especially for consumer electronics, these are set to see wide usage in the next few quarters.

 

ESD compliance at manufacturing facility
ESD compliance at manufacturing facility

Though there has been commendable progress within PCB manufacturing, this segment is still at a nascent stage in India. The upward trend still stays within very few Indian and global PCB fabrication houses who have their manufacturing in India. Most of the PCB fabrication houses still lag behind and need to have the understanding of the international standards and customer expectations. This is a major reason for increased cost of the boards fabricated in India, resulting in high dependency on PCBs from abroad.

Solder and associated material
SMT is driving the advances in solder materials, as the requirements for finepitch printing and reliable solder joint with minimal solder volume become a challenge. Smelting houses in India have been the main source of raw solder materials within the country for a long time.

With leading global solder consumable manufacturers sourcing raw materials from India, the manufacturing processes for smelting houses now meet world-class levels. 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 consumable manufacturers. This finally benefits the customers, specifically the CEMs who normally interact with more than one supplier.

Halogen-free requirement is another upcoming area of work. With this as a regulation, the challenges faced by the CEMs in India are very similar to the ones faced globally. This informa-tion is being used constructively by the solder material manufacturers.

Flux is now available in various forms—liquid, paste or solid—and various corrosion levels. This has significantly helped in soldering components of various types, which have various flux requirements within the same board, or which require more than one type of solder. One good example is customised components with castellation and thermal pad on 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 the chemicals used also have a heavy influence on the direction in which SMT moves. OEMs and subsequently the PCB fabricators are moving away from the metallic (hot-air solder leveling) and electroplated finishes (electroless nickel immersion gold and electroless nickel electroless palladium immersion gold) towards organic finishes (organic solderabilty preservatives (OSPs)).

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Major challenges with the organic surface finish are the fidelity of contact during the test of the PCB assembly and 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 undertaken by Indian academic institutions in partnership with the industry. The primary focus is on alternative lead-free solder alloys with soldering profile similar to legacy Sn63/Pb37 (tin-lead) alloy and also alternative to the widely used SAC (An-Ag-Cu) alloys. PCB surface-finish defects elimination in the wet process is another primary research area.

Equipment
Majority of the equipment used for electronics manufacturing, cleaning and inspection are imported. All the major equipment manufacturers either have direct presence or authorised dealers. Majority of the equipment vendors excel in post-installation and annual maintenance support. With most high-speed electronics equipment and advanced soldering equipment available, advanced manufacturing using six-sigma approach and meeting stringent goals is being done in India.

Rework equipment for advanced packages are another focus area. With several players working in the prototyping and rework segment, use of precision rework equipment—both automated and manual—has grown significantly.

Automated board handling is another area of high growth. These subsidiary equipment used along with the main assembly equipment help 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.

Tooling
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. IPC-7095 and different stencil design patterns and requirements are already known to the stencil manufacturers in India. In addition to these, various types of step-etched (level-etched) stencils are now in practice.

As more and more OEMs choose OSP as their preferred surface finish and move away from dual surface fin-ish designs, additional solder deposition challenges are faced by the stencil manufacturers—for example, requirements of less than 0.1016 millimetre (4 mil) of overall solder deposition to allow for both EMI suppression effect as well as 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.

Manufacturing line
Manufacturing line

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 meeting 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 real-estate requirement. In-circuit test (ICT) still remains the preferred test and programming stage 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) re-balling fixtures have seen phenomenal growth. These along with specialised requirement are available in India for quick turnaround times. Also, test fixtures for prototype requirements are readily available for introducing new products.

Facilities
Facilities in conformance with ANSI/ESD S20.20 certification are one of the primary requirements for electronics manufacturing. With every CEM and OEM seeking to establish electrostatic discharge (ESD) protection in its facilities, higher-level segregation based on the ESD sensitivity of the components being handled is used. Also, within the same ESD-protected area, smaller areas with specialised facility requirements are established to handle higher-sensitivity components (like

Lead-free manufacturing is another driver for resource requirement. Special requirements like nitrogen for high-temperature lead-free assembly introduce requirements for new facilities.

Electronics manufacturing
Unlike PCB fabrication, electronics manufacturing is setting its own global trends. 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 the boards from within the country provides enough challenge for the Indian CEMs. Further, the outsourcing strategy of global giants has helped replicate the best practices in manufacturing processes. Component package like 0402 is commonly used to increase package-on-package (PoP) density. Also, larger BGA packages with 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 circuits. These packages put forth the challenge of higher manufacturing process yields to meet the yield fall-out of these components.

Technological advancements in SMT machines

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The SMT equipment market is witnessing major technological innovations. Growing sophistication and the shrinking size of electronic gadgets is fuelling these advancements. Recent demand within the industry has been for high-precision complex boards and assemblies. At the same time, there is a constant pressure to improve the quality of the goods produced, aiming for zero defects. To be able to manage this, manufacturers need to have the right SMT equipment, which will enable fast, flexible and perfect production of PCBs.

Nowadays, a wide range of machines are available. These offer throughput as high as 25,000-45,000 components per hour, with mount precision as good as 30 microns. High-speed changeover facilities, intelligent tape feeders and conveyors, 5-megapixel inline inspection systems, high-speed and high-resolution automatic optical inspection (AOI) systems, soldering robots, automatic high-speed printers with 12-second cycle time, 10-micron repeatable accuracies at fine pitch and six-channel profiler packs for reflows are some examples of the latest technology available today.

In order to cater to the demands of manufacturers, SMT equipment are undergoing non-stop technical advancements, and some of the significant trends that have been observed in the field are increased parallelisation and flexibility, high levels of software integration, environment-friendly machines for RoHS-based production, machines that can handle smaller components at a faster speed, and small yet intelligent machines.

In addition, an upcoming trend in contract electronics manufacturing in India is to offer specialised engineering services as part of the PCB assembly introduction in the manufacturing floor. With the CEMs identifying many shortcomings in the OEM design in the post-manufacturing start, these are being introduced as engineering services. The CEMs look into the OEM design and highlight the possible additional tooling expenses due to violation of the design rule checklist that is drawn-up from the CEM’s capability.

Failure analysis
The probability of device failures has increased substantially with the miniaturisation of SMDs. Also, failure analysis of failed devices has become a challenge than ever before. Specialised equipment and skillsets required for the purpose are yet to catch up in India.

Most of the failure analysis is done by respective component vendors outside India. However, fab-less 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.

Standards
The growing demand for SMT in the electronics manufacturing segment in India has brought in the commitment from standardisation organisations like IPC, Electrostatic Discharge Association (ESDA) and 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 in 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 international platform from Indian perspective, and incorporation of feedback encourages further progress and brainstorming in the developing areas.

Training
SMT training is available in India at different levels. Training in equipment installation, handling and operation, and facility set-up is provided by the respective equipment vendor. However, operator-level training for hands-on repair or rework and inspection can be had within India.

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In-circuit testing
In-circuit testing

Engineer- and operator-level trainings in India are now at par with the internationally acceptable requirements, with IPC certifications available in India. The trainings start from the design, SMT process set-up, process validation, assembly, repair, rework and inspection. Innovative ESD training programmes, design for manufacturing, design for assembly and design for testability are some forthcoming areas. Programme management for CEMs is also an area of development that is expected to come up in India.

However, most of the trainings are customer-driven, specifically for contrast electronics manufacturing where the customer requirement pushes the training type. This is unlike OEMs, which have their manufacturing set-up in India and impart internal training as a new process requirement comes up.

Product data management
An electronic product involves multiple manufacturers in the supply chain at system or sub-system level—PCB fabrication, ASIC development and fabrication, PCB assembly, mechanical assembly and finally system integration and software installation.

Many a 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 Geber (file format used by PCB industry software) may lack valuable information which could be critical to the end-product’s quality.

Many services are coming up from Indian companies that are increasingly participating in product data management. These services help to establish communication between the participating partners as well as efficiently change the management. The IPC-2581 standard developed by IPC and International Electronics Manufacturing Initiative (iNEMI) is an xML-based scheme representing 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 Indian manufacturing’s point of view.

Specialised services
With increasing PCB assembly complexity, specialised services are being provided by companies to OEMs and CEMs. 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 test, electromagnetic interference/electromagnetic compatibility tests and ESD-qualification tests as per IEC standards.

Third-party certification services in line with these testing services are showing a huge growth in India for products in various applications including telecommunication, military and healthcare. These tests and qualifications are mainly performed at the system level, which verifies the mechanical strength and various other parameters of SMD solder joints.

Specialised rework services for boards with surface-mount components is an upcoming trend in different stages of the board’s life cycle—prototype, production and field returns. These include flip-chip components, package-on-package, inner-layer PCB laminate rework as well as rework of embedded discrete SMD components in the PCB.

Consultants for manufacturing process defects troubleshooting are sought by the Indian CEMs. Design consultation for new SMD component packages, thermal management and power rail design for multiple power rails on a board is also being sought by the Indian OEMs. Also, consultation for Six Sigma process and Japanese manufacturing methods like fool-proofing—in the form of Poka-Yoke and Kaizen (never-ending improvement process)—is being encouraged by the National Productivity Council. Clusters of Indian CEMs are being formed. Benchmarks within each cluster help improve manufacturing practices.

The way ahead
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 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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