Choosing the right chemicals for your PCB

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PCB chemicals, PCB manufacturingChemicals and consumables play a crucial role in the electronics industry, especially when it comes to PCB manufacturing

By Baishakhi Dutta

The market potential of the Indian PCB chemicals sector seems to be enormous, as it is directly affected by the performance and growth of the Indian electronics industry. This also means that the quality, supply and price of PCB chemicals impact the competitiveness of the PCB manufacturing industry. India had been a net importer of PCB chemicals in the 1990s, but with technological changes and an increase in demand, a few categories like solder paste, adhesives, solder fluxes and cleaning materials have started being exported gradually.

Different types of chemicals and their applications
Cleaning PCBs, stencils and electronic assemblies are vital to ensure long-term performance. The chemicals are primarily used for cleaning and degreasing and for thinning plastics, resins, glues, inks, paints and waxes. PCB chemicals can be broadly divided into wet cleaners, solder pastes, anti-static protection products, stencils, the safe-wash range, solvents, low VOC, conformal coatings, lubricants, resins, etc.

  • Wet process cleaning technologies account for about 89 per cent of what is used in microelectronics cleaning. They are used for PCBs, memory disks, electronic packaging and finishing, and in photovoltaic industries.
  • Dry cleaning technologies share the remaining 11 per cent – they comprise thermosetting single-components and solvent-free polymer adhesives, developed especially for the surface mounting of SMD components onto PCBs and for use on bare substrates.

The role of chemicals in miniaturisation
Today, the level of miniaturisation in electronics is a hundred times greater than during the 1980s, with the size of the components coming down to 0.1mm. Chemicals play a vital role in ensuring the reliability of these components.

Demand and growth rate
Long-term, reliable protection of sensitive circuits and components is important for today’s delicate electronic applications. With the increase in processing power and the emerging trend of smaller and more compact electronic modules, the need for chemicals and consumables is growing fast.
This market is a burgeoning one with the major demand coming from industries like electronics, aerospace, automobiles, EMS, solar and SMT.
The maximum demand for chemicals comes from the segments that use SMT reflow machines. The demand for soldering flux is, therefore, growing fast, and stood at 48,000 litres last year in India. The growth rate in the soldering flux market was approximately 35 per cent last year, and is poised to rise with the increasing adoption of SMT machines by the industry.

Local production vs imports
The local production of chemicals is limited; hence, the Indian industry is mostly dependent on imports, primarily from Europe and China. However, a few items like:

  • Solder paste
  • Adhesives
  • Solder fluxes, and…
  • Cleaning materials

…are manufactured in India, but all the raw materials needed to make them are imported. Almost 65 per cent of the flux consumed by the industry is sourced from local manufacturers.

A small percentage of the chemicals for electronics being produced locally are used in the domestic semiconductor, PCB and Flat Panel Display (FPD) industries. Multinationals like Henkel Corporation, Zestron, Kuraray and Ciba Specialty Chemicals are doing good business in the Indian market either through their direct presence or a dealer distributor network.

Innovations on the way
At present, customers mostly demand water based (aqueous) chemicals as these are environment-friendly; they have no flash point and do not foam. They can, therefore, be applied in all spray-in-air equipment, such as inline or batch systems. As circuits are becoming smaller, cleaning them is a challenge. Hence, cleaning chemicals must be modified and designed in such a way that low standoff components can also be cleaned without any problem.
According to Anil Kumar, MD, SLN Technologies, “Direct metallisation using horizontal wet process equipment for the PTH (plated through holes) process is already popular in India. There are some service companies that offer this process as an outsourced service in Gujarat. This practice is a good sign for the PCB industry. Small and medium sized companies can outsource this process, as investing in the relevant equipment is quite expensive.”
Another new technology is continuous vertical plating, which is already quite an established and proven technology in the Far East for PCB plating. In India, Atotech supports this technology, which involves a combination of special equipment and chemicals. There are a number of technologies available now for alternate finishes as well as plating technologies for HDI (high density interconnect) manufacturing.

Emerging market trends
Different chemicals have come into the market, and are available in crystalline and powder form. Some chemicals are now available in spray bottles as well, for clean and easy usage.
A lot of R&D has gone into developing water based cleaning technology, as it combines the advantages of traditional solvents and surfactants without their drawbacks. The combination of polar and non-polar compounds allows micro phase cleaning (MPC) agents to clean various organic and inorganic residues. MPC agents are not only non-flammable, but are extremely low in volatile organic compound (VOC) content, apart from being environment-friendly, cost effective and having excellent material compatibility.

Selection criteria
With such a wide range of chemicals with various features and benefits, it is important that the right chemical is chosen for the right application, because ill-chosen chemicals can have an adverse effect on subsequent running costs.
Solvents are easy to handle during the PCB cleaning process because they evaporate fast. But overall, the process is complicated as moving the chemical from one place to another is difficult, since these chemicals are dangerous. One can go for water based chemicals as they come with no storage problems.
Buyers should go for quality, and choose a supplier who has a strong support system and delivers on time. While buyers demand safe, effective and easy-to-use chemicals and consumables, they should choose chemicals that are not hazardous.

Hazardous chemicals used in PCB manufacturing and the implications of using them

  • Hazardous chemicals, such as brominated flame retardants, used particularly in the circuit boards and plastic casings of phones and computers, are major causes of severe pollution, neurotoxicity (due to the TBBPA chemical), impaired learning and loss of memory functions due to their high bio-accumulation tendency.
  • Lead, used largely in cathode ray tubes (CRT), causes intellectual impairment in children and damage to the nervous, blood and reproductive systems in adults.
  • Cadmium, used in rechargeable computer batteries, contacts, switches and in older CRTs, affects the kidneys and bones.
  • Mercury, used in lighting devices for flat screen displays, can damage the brain and central nervous system, particularly during early development.
  • Polyvinyl chloride (PVC), a chlorinated plastic, releases chlorinated dioxins and furans on disposal, apart from some other highly toxic non-degradable chemicals.

Just as the overall R&D scenario is bleak in India, the situation in the chemical industry is no better. Since very little is being manufactured in India and most of the chemicals and consumables used in the electronics industry are being imported, R&D is done by the foreign principal companies to maintain quality, keep pace with the fast changes in technology and match the requirements of the Indian industry. This indicates that little innovation has gone into the chemicals manufactured in India.

Some companies supplying PCB chemicals

  • Cookson Electronics
  • Henkel
  • Dow Corning
  • Mectronics Marketing Services
  • Electrolube
  • Zestron

Chemicals are in demand for the following purposes:

  • Stencil cleaning
  • Underside stencil cleaning
  • Misprint PCB cleaning
  • PCB defluxing/cleaning
  • Maintenance cleaning
  • Reflow/wave soldering cleaning
  • Fluxes

Chemicals used for miniaturised PCBs

  • Detergents
  • Light petroleum distillates
  • Formulated hydrocarbons
  • Brominated solvents
  • Glycols and fluorinated solvents

Parameters to be considered while choosing PCB chemicals

  • The working environment
  • Surface type
  • Sensitivity of devices being handled
  • Method of application

Buyer’s view

Anil Kumar Muniswamy
Anil Kumar Muniswamy, MD, SLN Technologies Pvt Ltd

Demand for PCB chemicals
The demand for PCB chemicals is increasing steadily by about 20 to 25 per cent every year.  At this moment, the demand is mainly from micro and small manufacturers.

Local production vs imports
Chemicals that have been indigenously developed with local branding mainly address micro, small and medium sized manufacturers. However, there are a couple of MNCs that manufacture very high quality PCB chemicals, and they cater to high-end and high-volume customers. These MNC brands are doing a good job, and they also provide very good service. Except for the cost, they are good in all respects.

Parameters that need to be tested for quality assurance
A chemical lab should have the latest testing facilities to test the quality and the thickness of the plating. Setting up a lab for cross-section analysis or electron microscopes calls for huge investments.

Role of PCB chemicals in miniaturisation
PCB chemicals play a major role in PCB manufacturing, which is highly process driven. The quality of plated through holes and the surface finish depends entirely on chemicals. Modern chemical technologies enable manufacturers not only to make high quality PCBs, but also to achieve high yields and productivity levels.

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