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Sanctions Against Sn/Pb Solder Paste
December 31, 1969 |Estimated reading time: 5 minutes
This article focuses on alternatives to tin/lead solder paste available to manufacturers, their effectiveness in substituting for tin/lead solder paste and their impact on the market.
By Bhargava Attada and Mandeep Singh Oberoi
Solder paste using tin/lead, popularly known as Sn/Pb has been the most important element of solder paste until global agencies threatened its popularity in favor of lead-free solder paste and other environmentally friendly alternatives. Although this has not taken effect effusively, the market is uncertain as to what the effect will be of the European Union's regulation to eliminate lead from electronics manufacturing by 2006. It will take time for lead-free to become effective.
Few innovations have come to the manufacturers' rescue because research and development (R&D) in this area is meager. A few that made an impression in the market and the extent of their impact on the overall solder paste market include:
- Lead-free solder paste
- No-clean solder paste (lead-free version)
- Electrical conductive adhesives (ECA)
- Embedded chips.
Lead-free Solder Paste
Alloys used for lead-free solder paste do not perform at the same level as current lead-based alloys. Some performance issues relate to solder joint reliability. Lead-free products also will require more inspection, reducing production yields and increasing capital equipment expenses. Some of the most common alloys used for lead-free solder include diverse compositions of tin/silver/copper (Sn/Ag/Cu).
This configuration is more environmentally friendly than the lead-based version. However, in general lead-free alloys do not perform as effectively as tin/lead. A popular metal used is a combination of copper, antimony, silver and tin (CASTIN); however, it is expensive. The performance of a board manufactured using lead-free solder is dubious because solder strength and joint reliability are low. The peak reflow temperature profile of these pastes range from 250° to 260°C, a temperature that damages most surface mount devices. Therefore, lead-free solder paste is unsuitable for high-volume production. Demand currently is low from high-volume producers like EMS providers.
Major problems associated with lead-free solder paste include:
- Joint reliability issues
- Surface finish problems
- Components becoming dysfunctional at higher temperature profiles
- Low solder strength.
No-clean Solder Paste
No-clean solder paste makes the cleaning process redundant, reducing capital expenditure for the manufacturer. In the past few years, the market has undergone a major shift toward no-clean solder paste. However, earlier versions of this solder paste contained lead. Lead-free no-clean solder pastes are being introduced to manufacturers.
However, lead-free no-clean solder paste typically requires melting temperatures at which some components malfunction or become largely dysfunctional. This also is costlier than conventional pastes, a significant deterrent for manufacturers to covert fully to lead-free versions. Particularly in defense applications, where reliability is a prerequisite, lead-free solder has no place. However, it can serve some purpose in consumer electronics with a shorter life span.
Another key issue is that the no-clean solder paste leaves a small residue on the board, defeating the purpose of no-clean, although less frequently. Cleaning would be more difficult compared to conventional solder pastes. Finally, no-clean solder paste suffers from performance issues. To adapt to this, the manufacturing technology must be altered slightly, inviting capital investment.
The no-clean solder paste market now is more than half the size of the total market. An upcoming report from Frost & Sullivan estimates it to be two-thirds by 2005. This growth can be attributed to two factors. The sanctions against using lead in solder paste are likely to take full effect post-2005 in North America and Europe, and in another 10 years in the rest of the world. Second is the inability of lead-free alloys to be perfect substitutes for lead. More R&D is necessary before these solders can solve the problems associated with lead-based solder paste.
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Electrical Conductive Adhesives (ECA)
ECAs completely eliminate the soldering function. This makes the investment in soldering and cleaning unnecessary, saving a significant amount of capital investment for the manufacturer. Electronics manufacturing services (EMS) providers desire such products because they need faster cycle times and greater speeds. One more area of application for ECAs is double-sided PCBs, where adhesives are necessary to hold the components on one side while components are being attached on the other side. Though costlier than regular solder paste, the overall process is cheaper because it eliminates soldering completely. The double-sided PCB market was forecasted to drive revenues from ECAs; however, demand for these double-sided boards is expected to remain flat in the future, thus restraining demand.
The slow dispensing process of these devices tempers the advantages. ECAs cannot match the speed of placement and other SMT manufacturing equipment, especially with the advent of advanced chipshooters, thus decreasing yield. They also suffer from unstable and/or weak conductivity compared to metals. Additionally, the lack of competition and proper R&D investment undermined the ECA market, and it has remained in the nascent stage. Players in this market are few, and the market currently is less than 2 percent of the total solder paste market. More R&D is likely to flow into this area when regulations tighten in favor of environmentally friendly options, and ECAs should evolve to be technically stabilized. In the short term, ECAs have low growth potential.
Embedded Chips
Embedded chips are minute devices with built-in digital logic designed to perform a specific function. They work at a clock speed of more than 50 MHz with a storage space crossing 256 MB. They are embedded directly into the PCB at the time of manufacture, making soldering unnecessary. These chips hit the market and found application in desktop computers in the 1960s and now are finding application in consumer electronics such as mobile phones, automotive electronic components and industrial applications like factory automation equipment. Most mobile technologies and automobile electronics are microprocessor-based and composed of embedded chips.
Much growth is expected from technologies such as field programmable gate arrays (FPGA). Geographically, the United States and Europe dominate the embedded systems market. It is likely that these chips will find application in everyday life and seize a large part of the PCB manufacturing market.
Market Sizes and Forecasts
According to Frost & Sullivan's forthcoming report on the world solder paste market, the industry was estimated as $250 million in 2002. The table shows the market estimates of the popular soldering paste types considered in the study. No-clean solder paste fell approximately 16 percent in 2002 due to lack of demand from the telecommunications and computer sectors. Lead-free has registered growth of about 33 percent this year, and is expected to experience strong growth over the next five years. Additionally, the ECA market is very nascent in nature and comprises less than 2 percent of the total market.
Manufacturers' attitudes toward solder paste should change from a commodity to a technology product. This, coupled with increased regulations from environmental agencies across the globe, is expected in the near term and more R&D expense is likely in this area, increasing innovation and product development.
For more information, contact Julia Paulson, Frost & Sullivan, (210) 247-3870; E-mail: jpaulson@frost.com.