Reasons for the surge in use, and the basics of a well-designed process.

Lead tinning has experienced a surge in popularity recently for a number of reasons, a leading one being the effect of RoHS on SnPb lead-finished component supplies and high-reliability electronics manufacturers’ need for these hard-to-find components.

The need for lead tinning has been around for nearly 25 years. The original need arose when the military decided that plated finishes – which are not fused – were not suitable or acceptable for high-rel environments. The problem at the time was plated finishes were found not to be sufficiently robust to withstand oxidation encroachment to the base lead, and could result in solder joint failure in the field. That process gradually diminished in necessity over the years, but for that and other reasons has now returned.

There are primarily four reasons why hot solder dipping is back in vogue. The first is for legacy components: those that might have plated finishes on their leads and need to be dipped for the same original reason; i.e., applying a robust, fused solder finish. The second is it is a good way to “scrub” the gold off component leads. Gold is initially plated on to help them stand up to the rigors of the burn-in process. That gold must be removed because it can cause embrittlement in the solder joint if it remains. Removal is achieved by hot solder dipping to “wash” off the gold.

The third reason is mitigation of tin whiskers, something everyone seems rightfully concerned about, thanks to the conversion to high tin content Pb-free alloys. Even NASA has published papers that say, in effect, that the only reliable way to mitigate tin whiskers and prevent their growth is to dip the leads in molten alloy. This creates a fused intermetallic finish unlike the non-fused electroplated finishes, which are a lot like a coating of sand – not fused or connected and prone to tin whisker development under certain conditions.

The fourth reason, for the high-reliability environment, is to convert components to be compatible with SnPb assembly. Since RoHS, fewer components are in stock with SnPb lead finishes, and those that aren’t must be hot solder dipped in a SnPb bath to make them suitable for assembly in high-reliability products. Hot solder dipping, done properly, will wash off the tin so the leads can be properly re-plated with SnPb.

In automated lead tinning, this must be done with a two-pot system. One pot absorbs the contamination, and its purity must be monitored, and it must be exchanged for a fresh pot when the level of gold or unwanted material reaches a certain saturation point. Then a second, or virgin, pot must be used to re-plate the leads with fresh and uncontaminated material. One does not try all this with one pot! Of course, the reverse is also common – SnPb-plated components are scrubbed of lead and re-plated with tin for use in RoHS-compliant assemblies, using two tin pots in succession.

There are a few basic but critical requirements for a successful automated lead-tinning process.  As mentioned, dual solder pots are a must: one for the cleansing or scrubbing, and a second virgin pot for re-plating with the correct alloy.

The second requirement is a flowing, not static, solder pot. Flowing solder, particularly in the scrubbing pot, removes contaminated or scavenged material such as gold from close proximity to the leads, so that the contamination will not be pulled back to and deposited onto the component lead when the part is pulled from the solder. It’s also important to have some sort of agitation in the first, or scrubbing, pot, as this actually helps remove gold or lead solder from the leads. This can easily be accomplished with mechanical manipulation of the device holding the component in the bath.

The use of nitrogen blanketing or inert atmosphere in the second, or finishing pot, is desirable because it promotes a lustrous finish, and mitigates the formation of dross, icicles and bridging.

Alan Cable is president of A.C.E. Production Technologies (ace-protech.com); acable@ace-protech.com. 

By increasing the FOV, on-board inspection is now feasible.

Solder paste printing is widely recognized as a common source of defects in the surface mount assembly process. One approach to increasing yields associated with solder paste deposition is to detect print defects immediately after the print operation, and reject defective boards before component placement. This enables SMT manufacturers to save time otherwise wasted in the assembly of defective boards, and avoids costly rework or scrap.

These defects can be detected in two places: inside the printer with an on-board inspection system or outside the printer with a 3D solder paste inspection system. SPI machines have come a long way since their introduction. We will leave that topic for another day, however, and focus on in-printer inspection.

Ideally, a stencil printer, in combination with stencil and solder paste, would deposit paste right on the pad, never deviating from the exact volume. That rarely happens, due to the noisy environment associated with the printing process. Instead, board assemblers spend considerable time using various inspection methods to verify printed board integrity. Inspection clearly reduces scrap, but can hamper throughput. As miniaturization becomes more common, post-print inspection becomes an economic necessity.

Most automatic stencil printers include on-board 2D inspection, each with its own advantages and disadvantages. Common to all inspection systems is that it adds time to the print process. Some systems take longer to inspect than others. The goal of a superior in-printer inspection system is to minimize inspection time, while providing required inspection data. There are several ways to accomplish this goal. Based on the process need, considerations include 1) inspecting a few selected components; 2) inspecting periodically; and 3) increasing inspection speed through some means to implement 100% inspection of the board.  

An elegant, clever way to increase inspection speed is to increase inspection area through a combination of camera, lenses and optics, especially by designing a system not governed by device pitch or feature size. From the camera prospective, the area under inspection at any particular time is known as “field of view” (FOV). A simpler definition of FOV is the area seen through the vision system. For example, consider Figure 1. It shows FOV 2 is nearly four times larger than FOV 1. In theory, then, the inspection time for the board shown will be nearly four times faster with “2” FOV. 

In a recent study, this theory was put to test by comparing two camera systems with a FOV ratio of nearly 1:4. Three different size boards with different device densities were inspected using two cameras. Camera 1 had a FOV of 87.5 mm2, and Camera 2 had a FOV of 320.9 mm2, which means FOV 2 was 3.8 times larger than FOV 1. All inspections were carried out under identical conditions, with the exception of camera type (Figure 2). As we see, based on the board type, Camera 2’s inspection speed is up to 3.4 times faster than camera 1.

In the past, especially for large, complex boards, 100% inspection inside the printer was impractical and time-consuming. With the introduction of larger FOV options, in-printer inspection becomes a true option. Inspection such as the one described here is not only capable of decreasing cycle time, but also capable of providing quantitative data down to the individual pad level, with information about pad overage, overprint, paste transfer and various levels of bridging. Based on the specific application, it has the potential of eliminating the need of a downstream SPI machine.

Rita Mohanty, Ph.D., is director advanced development at Speedline Technologies (speedlinetech.com); rmohanty@speedlinetech.com. 

On April 6 in Las Vegas, CIRCUITS ASSEMBLY handed out its annual Service Excellence Awards for the 18th time. The program recognizes EMS providers and electronics assembly equipment, materials and software suppliers, as judged by entrants’ own customers.

In previous years, the reception was held the day before the exhibit hall opened; this year, the event took place during the show. Participants said they appreciated the convenience of the location and the timing, which allowed customers to witness the proceedings.

Amid cheers, clapping and flashing cameras, EMS firms with the highest overall customer service ratings were announced, including repeat winner Mack Technologies in the large company (more than $100 million) category, Western Electronics in a highly competitive medium company ($20 million to $100 million) category, and returning winner, Krypton Solutions in the small company category (under $20 million).

Other EMS firms were honored in each of five individual service categories. (Overall winners were excluded from winning individual categories.) In the small-company category, Screaming Circuits held the top spot in the areas of dependability/timely delivery and manufacturing quality, and tied with I. Technical Services for responsiveness and technology. I. Technical Services won the value category.

In the medium-company category, Applied Technical Services took highest honors for dependability/timely delivery and responsiveness. NBS Corp. won for quality, technology and value.

In the large company category, EPIC Technologies swept all five individual categories for the second year in a row.

Electronics assembly equipment award winners were Assembléon America for pick-and-place; DEK International for screen printing; Kyzen Corp. for cleaning/processing materials; YESTech for test and inspection; OK International for soldering equipment; Nordson EFD for materials, and Air Vac Engineering for rework/repair. Aegis Industrial Software received top honors yet again in the manufacturing/supply chain management software category.

A donation of $2,500 was made on the participants’ behalf to the Surface Mount Technology Association’s Charles Hutchins Educational Grant. Part of each participant’s entry fee was included in the donation. CIRCUITS ASSEMBLY has contributed more than $55,000 to the fund over the years.

In addition to honoring the SEA winners, CIRCUITS ASSEMBLY and PCD&F gave awards for the 2010 New Product Introduction Award for electronics assembly equipment, materials and software, as well as PCB design and fabrication.

The NPI Award, in its third year, recognizes leading new products during the past 12 months. An independent panel of practicing industry engineers selected the recipients.

The winners included Production Solutions for its Red-E-Set Ultra HD for automation tools. In the cleaning equipment category, Aqueous Technologies took home the prize for its Trident Quad. Kyzen received an award for cleaning materials with Aquanox A4703, while Assembléon received top honors for its MC-24X in the high-speed component placement category.

For multi-function component placement, Europlacer won for the XPii-II SMT Assembler, and Data I/O scored a win for device programming with FlashCORE III.
Polyonics received an award for labeling equipment with its XF-781 Thermal Transfer Printable Polyimide, and FCT Assembly won for NC160 Flux in the flux materials category.

For process control tools, KIC took top honors for e-Clipse Thermocouple Attachment, and R&D Technical Services won for rework/repair tools with Vaporworks 24 Rev 2.

DEK’s VectorGuard Platinum Dual Layer Stencil won for screen/stencil printing, while Panasonic was honored for production software with PanaCIM Enterprise Edition. Microscan and its TTC solution received an award for process control software, and Valor won for management software with MSS.

In the soldering materials category, Cobar Solder Products won for Aquasol. For reflow soldering, Speedline Technologies won for the OmniMax reflow soldering system. Juki was honored for selective soldering with the Inline Flex Solder W510. Wave soldering went to Seho Systems for Real-Time Fluxer Control, and soldering (other) went to EVS International for the EVS 9000 solder dross recovery solution.

For ICT, Acculogic was honored for the FLS980Dxi Flying Scorpion. Koh Young took top honors for AOI with the Zenith 3D AOI system, and Henkel won in the adhesives category for Hysol Eccobond CA3556HF.

For laminates, Rogers received an award for RO4360 Thermoset. WKK held the top spot for imaging for its X-Pose SM120 exposure system. National Instruments won for system modeling and simulation tools for NI Multisim 11.0 circuit simulation and analysis software, and for PCB design tools, Sunstone Circuits’ PCB123 took home the prize.

After a difficult 2009, this show was upbeat and hopeful for the rest of 2010 and beyond. The awards reception was no exception. SEA winners and other participants alike were eager to receive reports providing feedback from their customers, and the sheer number of NPI entrants is a positive sign that in a slow growing economy, companies are still focusing on bring new technologies to market.

Look for 2011 award program information at circuitsassembly.com and pcdandf.com in the summer months.

Chelsey Drysdale is senior editor of CIRCUITS ASSEMBLY; cdrysdale@upmediagroup.com.

Mature was the word at North America’s largest electronics manufacturing equipment show.

While attendance at the Apex trade show in early April was up over last year – although nothing to write home about (show producer IPC reported a 10% hike, to 3,700) – the mood was decidedly improved. After a slow first morning, show traffic ramped and stayed steady throughout the remainder of the show, even on the last day, which is highly unusual.

Perhaps the sign of a mature industry is the lack of lunar leaps in process technology. SMT has settled on a stream of steady improvements, but few of late have envisioned – let alone brought to market – truly revolutionary products. Still, there were some notables.

One printing advancement was Milara’s (milarasmt.com) decision to group its Touch Print Digital TD2929 printer with Mirae’s Mx400LP pick-and-place, which resulted in the P3, a dual-lane, high-speed hybrid that can simultaneously print, dispense, inspect and place parts.

DEK (dek.com) is helping customers realize better asset management, offering remote diagnostic and service on its machines. While this has been attempted before, and without many takers, DEK’s twist is to offer the service on demand, allowing customers to control the flow of data and IP – one of the hurdles of previous remote service efforts. DEK president Michael Brianda said the company, which has been moving much of its stencil manufacture to licensees (Fine Line Stencil in San Jose being the latest franchisee), will maintain facilities in key locales such as Germany and Singapore.

Most conversations with soldering materials suppliers centered on the so-called Conflict Metals, and whether they are or are not an industry problem. The big news was Heraeus’ (4cmd.com) decision to move solder production out of the US and reduce its headcount at its Pennsylvania plant accordingly, a consolidation scheduled to be completed by year-end. Separately, Nihon Superior (nihonsuperior.co.jp) president Tetsuro Nishimura did allow that the SN100 inventor would not license additional vendors in the US. Balver-Zinn (balverzinn.com) featured a new water-soluble paste, called Aquasol. Type III remains the most popular powder size, but more customers are asking for Type IV.

In placement, most advancements were aimed at either putting more functionality on lower tier equipment, or adding speed.

Assembléon (assembleon.com) now offers a Twin Placement Robot for certain placement lines. The size of a feeder trolley and with two moving heads, TPR is designed to place DRAM and large modules. The company also now will sell its A5 placement machines and MCP printers in Asia.

Siemens (siplace.com) showed a novel changeable gantry whereby an existing Siplace SX line could be converted from or into a dual-gantry machine. In a demo, an operator added a gantry on-the-fly and had the machine programmed and running in about 15 minutes.

Universal Instruments (uic.com) has finished its reorganization, settling on six product lines: surface mount, semiconductor assembly, insertion machine, final assembly and automation, operational services and feeders. Some 70% of its business comes from surface mount, yet that business was down 54% in 2009, and the company now is also targeting semiconductor and NPI.

Most real advances in soldering came out at Productronica last November. At the end of the show, Seika Machinery (seikausa.com) and EVS International (solder-recovery.com) were discussing a partnership, though it is not a done deal. Seika had on hand the Solder Paste Recycling Unit – a “one of a kind machine” that reheats paste and turns it into solder bar, separating the metals and dumping the flux. Some EMS companies lose as much as $80,000 a year in solder paste waste, Seika noted. Also gaining momentum is On Site Gas (onsitegas.com), which provides custom machines that convert air to nitrogen.

Cleaning continues to be a hot spot: Sessions were packed (an estimated 80 to 100 persons in all). Kyzen (kyzen.com) launched Aquanox A4703, an aqueous cleaner it says would fit well with the growing sentiment that asserts “water-soluble can’t just work with water anymore.” (Water-soluble paste makes up about 10% of North American production, according to Kester’s Peter Biocca.) Aqueous Technologies (aqueoustech.com) updated its Trident Quad batch system with a 16" monitor for the system and – in a twist – Skype-based video conferencing. Zestron (zestron.com) continues to push the envelope of “green” chemistries. Finally, Seika (seikausa.com) formally introduced Sawa’s Eco-Roll wiper roll cleaner, said to make rolls reusable up to 10 times.

Test and inspection is all over the map. There is a steady demarcation of equipment by price, and the lower tech machines continue to drag down the ASPs of the state-of-the-art. Acculogic (acculogic.com) showed the Flying Scorpion 900DX flying probe, said to replace in-circuit test without the need for a test fixture. It enhanced the automation of its Scan Navigator software. Mirtec (mirtecusa.com) has added a 15-MP camera to its Isis AOI. SPI market leader Koh Young (kohyoung.com), the star of last year’s show with its Zenith 3D AOI, still draws kudos for its ingenuity – the system uses moiré technology to pattern assembled boards – but remains outside looking in (for now), as it spent the past year beta testing the machine, improving the system’s software and documentation, and lining up distributors.

Not So ‘Fab’
For all the advances on the assembly side, there was little to offer on the fabricators. (At Apex, printed circuit board design is not just an after-thought; it barely exists.)

The big news was the announcement by a group of Silicon Valley semiconductor veterans of a new direct-write digital imaging technology for printed circuit board production. After five years in development, Maskless Lithography’s (maskless.com) MLI-2027 direct-write lithography system is said to feature high throughput, yield and accuracy using standard resists. It carries a patent for its imaging technology. The technology has been beta-tested and qualified by Sanmina-SCI (sanminasci.com) at its San Jose plant, and will be distributed by Technica (technica.com).

3M’s (mmm.com) Embedded Capacitance Material is now halogen-free. Now that Sanmina’s patent on buried capacitance has expired, materials from 3M, DuPont (electronics.dupont.com) and others are poised to take off.

Speaking of DuPont, the materials giant showed a plethora of new materials, perhaps the most interesting of which was the CB500 removable conductive silver plating ink, a screen-printed ink for selective electroplating. It is said to eliminate the need for bus bars or other copper plating connections, and remove the need for after-plating.

On the software side, in the wake of their recent merger, Mentor Graphics (mentor.com) and Valor (valor.com) representatives emphatically stressed that the company's proprietary data transfer format would continue to provide complete support to non-Mentor CAD tools.

“It doesn't make business sense to cut off revenue from the DFM side," Julian Coates told this magazine. "And it gives us an opportunity to talk to [the customer] using competitive [software].”

Company officials said they would leave open the opportunity for other PCB CAD vendors to work on future revisions to the format. However, the company held out that changes may be coming that more tightly integrate ODB++ with Mentor's CAD suites, including Pads and Expedition. “Our desire is to work openly with other CAD companies," Coates said. “I hope they will see the net balance is positive [for them].” No discussions with other CAD vendors have yet taken place, he added.

Valor, which will be operated as a standalone business by Mentor, will continue to develop the ODB++ format. The format is used to transfer data from CAD to CAM machines and to assembly and test equipment.

All in all, this year’s show was perceived much improved over the 2009 edition. Exhibitors seem to have accepted that a show that draws, say, 2,500 attendees, may be all that North America is capable of, and provided they are qualified and ready to buy, that’s good enough.

Mike Buetow is editor-in-chief and Chelsey Drysdale is senior editor of CIRCUITS ASSEMBLY (circuitsassembly.com); mbuetow@upmediagroup.com.

SEA, NPI Awards Revealed

On April 6 in Las Vegas, CIRCUITS ASSEMBLY handed out its annual Service Excellence Awards for the 18th time. The program recognizes EMS providers and electronics assembly equipment, materials and software suppliers, as judged by entrants’ own customers.

In previous years, the reception was held the day before the exhibit hall opened; this year, the event took place during the show. Participants said they appreciated the convenience of the location and the timing, which allowed customers to witness the proceedings.

Amid cheers, clapping and flashing cameras, EMS firms with the highest overall customer service ratings were announced, including repeat winner Mack Technologies in the large company (more than $100 million) category, Western Electronics in a highly competitive medium company ($20 million to $100 million) category, and returning winner, Krypton Solutions in the small company category (under $20 million). 

Other EMS firms were honored in each of five individual service categories. (Overall winners were excluded from winning individual categories.) In the small-company category, Screaming Circuits held the top spot in the areas of dependability/timely delivery and manufacturing quality, and tied with I. Technical Services for responsiveness and technology. I. Technical Services won the value category.

In the medium-company category, Applied Technical Services took highest honors for dependability/timely delivery and responsiveness. NBS Corp. won for quality, technology and value.

In the large company category, EPIC Technologies swept all five individual categories for the second year in a row.

Electronics assembly equipment award winners were Assembléon America for pick-and-place; DEK International for screen printing; Kyzen Corp. for cleaning/processing materials; YESTech for test and inspection; OK International for soldering equipment; Nordson EFD for materials, and Air Vac Engineering for rework/repair. Aegis Industrial Software received top honors yet again in the manufacturing/supply chain management software category.

A donation of $2,500 was made on the participants’ behalf to the Surface Mount Technology Association’s Charles Hutchins Educational Grant. Part of each participant’s entry fee was included in the donation. CIRCUITS ASSEMBLY has contributed more than $55,000 to the charity over the years.

In addition to honoring the SEA winners, CIRCUITS ASSEMBLY and PCD&F gave awards for the 2010 New Product Introduction Award for electronics assembly equipment, materials and software, as well as PCB design and fabrication.

The NPI Award, in its third year, recognizes leading new products during the past 12 months. An independent panel of practicing industry engineers selected the recipients.

The winners included Production Solutions for its Red-E-Set Ultra HD for automation tools. In the cleaning equipment category, Aqueous Technologies took home the prize for its Trident Quad. Kyzen received an award for cleaning materials with Aquanox A4703, while Assembléon received top honors for its MC-24X in the high-speed component placement category.

For multi-function component placement, Europlacer won for the XPii-II SMT Assembler, and Data I/O scored a win for device programming with FlashCORE III.

Polyonics received an award for labeling equipment with its XF-781 Thermal Transfer Printable Polyimide, and FCT Assembly won for NC160 Flux in the flux materials category.

For process control tools, KIC took top honors for e-Clipse Thermocouple Attachment, and R&D Technical Services won for rework/repair tools with Vaporworks 24 Rev 2.                  

DEK’s VectorGuard Platinum Dual Layer Stencil won for screen/stencil printing, while Panasonic was honored for production software with PanaCIM Enterprise Edition. Microscan and its TTC solution received an award for process control software, and Valor won for management software with MSS.

In the soldering materials category, Cobar Solder Products won for Aquasol. For reflow soldering, Speedline Technologies won for the OmniMax reflow soldering system. Juki was honored for selective soldering with the Inline Flex Solder W510. Wave soldering went to Seho Systems for Real-Time Fluxer Control, and soldering (other) went to EVS International for the EVS 9000 solder dross recovery solution.

For ICT, Acculogic was honored for the FLS980Dxi Flying Scorpion. Koh Young took top honors AOI with the Zenith 3D AOI system, and Henkel won in the adhesives category for Hysol Eccobond CA3556HF.

For laminates, Rogers received an award for RO4360 Thermoset. WKK held the top spot for imaging for its X-Pose SM120 exposure system. National Instruments won for system modeling and simulation tools for NI Multisim 11.0 circuit simulation and analysis software, and for PCB design tools, Sunstone Circuits’ PCB123 took home the prize.

After a difficult 2009, this show was upbeat and hopeful for the rest of 2010 and beyond. The awards reception was no exception. SEA winners and other participants alike were eager to receive reports providing feedback from their customers, and the sheer number of NPI entrants is a positive sign that in a slow growing economy, companies are still focusing on bring new technologies to market.

Look for 2011 award program information at circuitsassembly.com and pcdandf.com in the summer months. – Chelsey Drysdale