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Palladium Methods

Palladium systems use palladium particles to catalyze nonconductive surfaces of the through-holes. Palladium particles tend to agglomerate (cluster) unless they are stabilized through the formation of a colloid, which surrounds the individual palladium particles with a protective layer. The two main categories of stabilizers are organic polymer and tin.

Initially, a conditioner solution creates a positive charge on the substrate surface. For organic-polymer/palladium colloids, a predip solution conditions the surfaces of the vias with a polymer film that acts as an adhesion promoter for the colloids. When the substrate is introduced to colloidal suspension, the tin/palladium colloids adsorb onto the slightly charged surfaces, and the organic-polymer/palladium colloids adsorb onto the film-covered through-hole walls. The adsorbed colloidal particles form a nonconductive coating on the through-hole walls. The substrates are then placed in an accelerator solution (for tin) or a postdip solution (for organic polymer) which removes the stabilizers, exposing a conductive layer of palladium particles in the through-holes.

A typical palladium process has six chemical process steps (cleaner/conditioner, microetch, predip, catalyst/conductor, accelerator/postdip, and acid dip), as shown in Figure 3.

Information is presented on the following palladium methods:

Organic-stabilized method:

  • Neopact (Atotech U.S.A., Inc.)
Tin-stabilized methods:

  • Conduction DP (LeaRonal Inc.)
  • Crimson 1® (Shipley Company)
  • Envision DPS (Enthone-OMI, Inc.)
  • HN504™ (Solution Technology Systems)
Figure 3. Typical Palladium Process Steps

Figure 3. Typical Palladium Process Steps

Neopact (Atotech U.S.A., Inc.)

Neopact is an organic-stabilized palladium-based technology available in both non-conveyorized (vertical) and conveyorized (horizontal) configurations. The Neopact system is quite versatile, working on a wide variety of substrates, boards with many layers, and boards with very small holes. Many Neopact customers produce complex boards, typically with ten or more layers. Although electroless copper is likely to be more effective than direct plate for extremely thick boards, the difference in quality is narrowing with experience, according to the vendor, Atotech U.S.A., Inc. Hole diameter sizes of 0.008, 0.010, 0.013 inches, and some as small as 0.006 inches have been through the qualification process. Neopact users work with a wide variety of substrates, including FR-4, Teflon®, polyimide, acrylic flex, non-acrylic flex, and epoxy.

Implementation at Specific Facilities
Two facilities (Facilities H and I) that have successfully implemented the Neopact process were interviewed for this report. Their primary motivations for switching to the new process included the elimination of formaldehyde, lower costs for labor and support materials, and decreased water use. Facility H chose the Neopact process because it was capable of running the wide variety of substrates that the facility uses. In addition, some systems offered by other vendors utilize a permanganate desmear, which only works on epoxy. The use of permanganate would not have been compatible with Facility H's plasma desmear operation. Facility I switched to the Neopact system in January 1996 after nine months of experiencing problems with voids using a palladium process supplied by a different vendor.

  • Elimination of formaldehyde
  • Reduced labor and material costs
  • Decreased water use
  • Ability to run a variety of substrates

Both facilities used an existing, computer-controlled, non-conveyorized (vertical) rack system for the Neopact process. Installation at Facility H took four days, and there were no unexpected expenses. Facility H's only equipment modification was the addition of a heating and cooling coil to one of the process tanks. This facility first ran a prototype system, which underwent a two-week debugging process followed by eight months of end-user qualification testing. The company had to qualify the new process to meet military qualifications and other customer requirements. At that point, the Neopact system was incorporated into the main production line.

Installation at Facility I took approximately two to three days. During this period, however, the facility discovered additional equipment needs that were not anticipated. These unexpected expenses for line set-up included heating coils on one tank and a flash-plate step to allow for void detection.

The vendor, Atotech U.S.A., Inc., noted that when a Neopact system is installed in a conveyorized (horizontal) configuration, the debugging timeline is much longer due to the complex nature of the installation and start-up of automated equipment. It usually takes three to five months to install and debug the chemistry and equipment. The vendor strongly recommends using its own equipment (sold under the trade name Uniplate) to minimize debugging and control problems.

Experiences with the Neopact Process
In Atotech's experience, "facilities retrofitting existing tanks for the Neopact system usually go through a phase of four to six weeks during which a facility discovers unique qualities of its process that require adjustments" (e.g., analytical frequency, dumping schedules, and interactions with other equipment). This was true for Facility H, although its debugging period was shorter. Other than minor fine-tuning, Facility H did not encounter any problems during debugging.

After the Neopact system was in full production at Facility H, problems began to occur with the oxidation-reduction potential (ORP) controller on the palladium bath. Over time, the controller and probe failed, yet the operator could not immediately detect its failure. The facility eventually replaced the controller and probe with a more reliable one.

In contrast to Facility H, Facility I experienced problems with voids during the debugging process. On the advice of the vendor, the facility solved the problem by adding an extra step to the process (a "wetter" step), which required an additional tank and chemistry. A recycling pump was also added to allow for better circulation of the chemistry through the holes. At Facility I, it took about three months to get the system working properly. With the system fully operation, Facility I periodically experiences voids on all types of boards. When this occurs, the facility works with the local Atotech service representative to adjust the process chemistry. Inner and outer layer separation on multi-layer boards is another problem that occasionally happens, the solution to which the company is still investigating.

According to Atotech, voids have not been a commonly cited problem with the Neopact system. To inspect through-holes for voids, customers use the backlighting technique after flash or panel plating. If the customer pattern plates after direct plating, a backlight test coupon is used along with a microsection of the finished product. It is not possible to perform backlight inspection of the product unless it has been flash-plated. Regardless of the effective methods of inspecting for voids, some PWB manufacturers may have customer specifications (e.g., military) to use the solder float test followed by cross-sectioning. This is the case for Facility H. Neither company had significant problems with customer acceptance, although Facility H noted that some companies may be reluctant to accept the process because it is new.

Comparisons to Electroless Copper
Facility H found that cycle time and labor time required for preventive maintenance on the Neopact system are roughly the same as for electroless copper. However, the labor time necessary for process control has decreased by 50%, and the time spent on lab analysis has also been reduced. In addition, board quality is reported to be superior, and the board failure rate has been halved. Facility H noted no differences in copper discharge, sludge generation, or water usage. However, chelated wastestreams are not generated by the Neopact system.

The switch to the Neopact process at Facility I has resulted in a cycle time 50% faster than for electroless copper. The facility notes no differences in board failure rate and the amount of time spent on maintenance. Some changes in waste treatment have been required as a result of implementing the new process. Palladium-containing wastewater cannot be treated in the facility's resin-based treatment system, so it must be shipped off-site. On the other hand, some process wastes do not require treatment at all before discharge. With regard to environmental impact, Facility I has achieved reduced copper discharge, and savings in water usage, but sludge volume remains unchanged.

Atotech U.S.A., Inc. emphasizes that management must support all phases of the implementation, from installation to debugging to full production.

Keys to Success
Facility H emphasizes that close support from the supplier during start-up is critical to the success of this technology. PWB manufacturers who choose to implement this technology should request that the vendor supply a technician who has substantial experience setting up the system to work in the facility during the start-up period. Facility H attributes its success to a thorough evaluation of the process (e.g., plating distribution, post-separation resistance, chemical usage) prior to full production in order to facilitate customer approval.

For companies to be successful with the Neopact system, Facility I stresses that "training is very important because you are working with very sensitive chemistry." Operators must maintain process baths according to vendor specifications. "You can't stretch it when it's time to change [the chemistry] or else you'll have problems." Facility I also considers flash plating (to facilitate void detection) a necessary step "in order to have 100% confidence" that proper plating in through-holes is achieved.

Atotech emphasized that management needs to make a firm commitment to the alternative technology. Management must support all phases of the implementation, from installation to debugging to full production.

For more information on the Neopact system, contact Mike Boyle of Atotech U.S.A., Inc. at 803- 817-3561.

Conductron DP (LeaRonal Inc.)

The Conductron DP process accelerates the tin from the tin/palladium colloid, and at the same time reduces the copper back onto the palladium. The resulting layer of conductive palladium/copper is electroplated with copper. The Conductron process can be run for both non-conveyorized (vertical) systems (Conductron DP) and conveyorized (horizontal) systems (Conductron DP-H). According to the vendor, LeaRonal Inc., there are no substrate limitations, and a maximum aspect ratio of 26:1 has been run on a conveyorized (horizontal) system. Most of the facilities that run the Conductron process produce less than 500,000 surface square feet per year, but some large facilities have successfully installed the system as well.

  • Lower operating costs
  • Less water use
  • Quicker throughput
  • Increased worker safety
  • Ease of waste treatment

Implementation at Specific Facilities
Two facilities (Facilities J and K) that have successfully implemented the Conductron system were interviewed for this report. Primary motivations for switching to the new process included lower operating costs, reduced water use, quicker throughput, increased worker safety, and ease of waste treatment. One facility chose LeaRonal's Conductron system because the vendor had a lot of experience in the industry, the initial test results for Conductron were better than those for carbon and graphite systems, and the palladium technology is similar to that of electroless copper, making it easier to sell to customers.

Installation and debugging of the non-conveyorized (vertical) system at Facility J took approximately six months. Facility J did not purchase any new equipment and had no unexpected expenses during this time. Other facilities, according to LeaRonal, had typical equipment issues with the conveyorized systems during debugging. "With these complex systems, there is bound to be a problem with pumps, wiring, etc." Also, tap water contaminated baths at some facilities. In these cases, the facilities switched to deionized water.

Experiences with the Conductron Process
Facility J stated that "any printed wiring board manufacturer will experience intermittent problems" with plating through-holes. During full operation, the facility occasionally experiences variations in bath temperatures and contaminated chemistries caused by human error. The facility encounters about the same number of problems as it did with the previous electroless copper line. One customer--a military account--decided to take its business elsewhere, because it wanted a technology backed by many years of test data on performance. Nevertheless, Facility J meets military qualifications and can run Teflon¨, FR-4, and polyimide substrates. Facility K primarily uses an electroless copper line, but recently installed a conveyorized (horizontal) Conductron DP-H line to help with smaller orders that require quick turn-around time (e.g., prototype boards). The facility encountered some problems during debugging and testing of the Conductron line. There was excess dragout due to the squeegee rollers. This was solved by resurfacing the rollers. While there was no problem with epoxy coverage, there was inconsistent coverage for glass surfaces in the through-holes. Tin was also oxidizing out because of poor machine design. The equipment would aerate the solution, resulting in tin precipitating out. There were also problems with liquid level controls. To solve these problems, Facility K is planning to install a new conveyorized Conductron system. The new Conductron line is not meant to replace the existing electroless line.

Comparisons to Electroless Copper
Facility J spends more operator time on bath maintenance and lab analysis with the Conductron system than it did with electroless copper, while Facility K predicts its new system will need less time for analysis and chemistry bath maintenance. Facility J's Conductron line has a cycle time that is 60 to 75 percent faster than the previous electroless line; Facility K predicts the Conductron line's cycle time will be approximately 65 percent faster than electroless copper. The Conductron systems at both facilities generate less sludge and less copper waste.

Facility J believes it is very important to have excellent, well-established vendor support to successfully implement a new direct metallization system.

Keys to Success
Facility J believes it is very important to have excellent, well-established vendor support to successfully implement a new direct metallization system. The facility believes that LeaRonal has provided good technical support and is "very knowledgeable about the chemistry." Also, the facility emphasized the need for line operators who are willing to learn about the new technology. Facility K stated that the equipment is very important, and that the vendor's equipment recommendations should be followed. The Conductron system, according to both facilities, is "not as forgiving as electroless copper and requires more operator attention."

For more information on the Conductron DP system, contact David Schram of LeaRonal Inc. at 516-868-8800.

Crimson 1®, (Shipley Company)

The Crimson 1¨ system is a tin-stabilized palladium process. Crimson 1®, differs from other tin- stabilized palladium processes in that it uses a sulfide step to stabilize the surface of the accelerated substrate. After the sulfidization of the palladium sites, some sulfide adsorbs to the exposed copper of the inner layers. This coating tints the boards a crimson color (and thus gives the technology its name). A microetch step then removes the adsorbed sulfide from the interconnects. The final step of the process, a high-pressure water rinse, removes any remaining microetch from the board surface.

According to Shipley, 30 of 70 Crimson 1¨ facilities use a conveyorized (horizontal) configuration. In a non-conveyorized (vertical) orientation, Shipley recommends that only double-sided boards be processed, but a conveyorized (horizontal) system can process both multi-layer and double-sided boards. This difference is due to the difference in the fluid dynamics. In a horizontal (conveyorized) system, there is more control of the flow of the solution going through the holes. This increased control is important in successfully running multi-layer boards. Most new systems are conveyorized (horizontal) lines, according to the vendor,"now that more shops are doing multi-layers." The typical Crimson 1®, customer manufactures 60 percent multi-layered boards in volumes that range from 500 to 2,000 panels per day, with hole diameters of 0.008 inches and larger. The vendor notes, however, that 20 of these facilities process many more per day (for example, one processes 40,000 square feet per day of primarily double-sided boards, while another handles 30,000 square feet per day, 90 percent of which are multi-layer). According to the vendor, the current standard product mixes are being used successfully with the Crimson 1®, process, customers are successfully running exotic substrates through the system, and, in some cases, aspect ratios as high as 20:1 have been plated successfully.

  • Decreased chemistry costs
  • Faster cycle time
  • Less water consumption
  • Lower waste treatment costs
  • Improved worker health and safety

Implementation at Specific Facilities
Three facilities (Facilities L, M, and N) that have successfully implemented the Crimson 1®, process were interviewed. All three facilities run the process horizontally, with production volumes ranging from 1.44 to 9.6 million surface square feet per year. Their primary motives for switching to Crimson 1®, from electroless copper were decreases in chemistry costs, cycle time, water consumption, maintenance, and waste treatment costs, as well as improved worker health and safety. Debugging required the longest time at Facility M, the first U.S. manufacturer to use the Crimson 1®, process for multi-layer boards. This line, which was installed in the summer of 1993, took one month for physical installation and nine months for debugging. Facility L also installed its line that year, taking six months due to the large size of the line. Debugging required four months. Facility N installed its Crimson 1®, line in only two weeks in June 1996, with debugging requiring three months.

All three facilities had researched or experimented with other technologies before adopting the Crimson 1®, process. One facility experimented with carbon technology, and another facility experimented with graphite technology, but both experienced defect problems and overall process sensitivity. With the Crimson 1®, system, however, one facility said "we couldn't get it to fail." Another facility remarked that "the Crimson process appeared to be more robust than other direct metallization systems." The third facility selected Crimson 1®, based on its own research on the costs and voiding frequencies of alternative technologies.

Experiences with the Crimson 1®, Process
Since Facility M's original persulfate microetch also etched the palladium, the facility switched to a peroxide microetch. This change necessitated other downstream process changes. First, different waste treatment chemicals were needed due to peroxide gassing; they now use sodium metabisulfite to help suppress gas formation. Also, the sodium peroxide evaporated and needed refreshing if the Crimson system was not in use. Lastly, Facility M noted that the sulfide waste from the Crimson 1®, process requires special handling--the waste should be added directly to the batch treater to obviate hydrogen sulfide formation. The other two facilities interviewed also made adjustments to the process once it was operational.

All facilities experienced some minor process defects. Facility M reported negative etchback with Crimson 1®, that was "noticeable" but within customer tolerances. This facility noted that military or three-point connections (and thus military-specification boards) are not a possibility due to etchback. Facility N experienced slight hole-wall separation. Facility L found that microetch must be maintained within proper limits to insure consistent film removal. In addition, Facility L found that a board scrubber was necessary to remove a thin film layer from the board surface before sending boards to the lamination room. According to Facility N, Shipley now recommends board scrubbing to manufacturers installing their lines.

Facility N had some conveyor jamming problems when running thin-core materials (e.g., 0.006 inches). Jams would occur when improperly adjusted water pressures knocked panels out of clips. These problems were eliminated after spray pressures were adjusted and stronger clips were added.

Manufacturers did not report major hole size or board thickness limitations with the Crimson 1®, technology. Facility N experienced some failures with hole diameters of 0.008 inches, but solved the problem by experimenting with operating parameters. Newer versions of the Crimson 1®, system have improved filtration and spray bar configurations, according to Facility M. A Florida facility with a Crimson 1®, line is reportedly plating hole diameters as small as 0.008 inches and up to a 12:1 aspect ratio on "every material you can think of." According to Facility M, "Crimson 1®, can do everything, once properly configured."

Comparisons to Electroless Copper
All three facilities increased production throughput with the Crimson 1®, system. Facility M switched from a "typical electroless dip-and-dunk batch system" to the conveyorized (horizontal) Crimson 1®, process and saw large throughput increases. Facilities L and N doubled and tripled their productivity by switching from electroless copper to the Crimson 1®, system.

Manufacturers saw void frequency either decrease or stay the same. For Facility M, the Crimson 1®, process "reduced voids by 90 percent, at least." The manufacturer at Facility M "used to tilt boards, bang them, vibrate them, but still had a problem with voids" due to hydrogen bubbles in the holes of the vertically-hanging boards. Facility N noted that the "failure rate is one-third of electroless" and "more a function of drilling and drill debris than a failure of Crimson."

Time required for lab analysis decreased at all facilities. Facility M now conducts one analysis a shift (eight hours) instead of once an hour. Facilities L and M report that continuous monitoring is now not necessary and fewer parameters need to be analyzed overall.

Changes in maintenance requirements varied by facility. Facility M noted"We used to have to use a colorimeter to calibrate baths and pumps and were constantly fighting the metering pumps, but now we don't have to worry about it at all." Facilities M and N caution that "there is a lot of preventive maintenance on the [Crimson 1®,] line because it is so complicated." At Facility N, time spent on maintenance increased because of an extensive preventive maintenance schedule.

Facilities M and N saw water usage decrease. Facility M's water usage with the electroless system was 10 to 14 gallons per minute. Water use is 3 to 4 gallons per minute with Crimson 1®, because the"rinsing tanks on the Crimson line have a far lower rating than the electroless." Facility L did not track water usage.

For Facility M, the switch from electroless copper to the Crimson 1®, process did not appreciably change the concentration of copper in facility wastewater or the amount of sludge generated. However, Facility N saw a decrease in both. Facility L did not know if these factors had changed. All facilities reported lower air emissions (such as formaldehyde).

All three facilities reporting saving money with the Crimson 1®, system. Facility N reported saving 50 to 60 percent overall compared to the costs of an electroless system. Facility M stated that the Crimson 1®, process itself cost the same as electroless, but savings were possible in other areas such waste treatment, chemical maintenance, and lab analysis. This facility reported saving at least 30 percent overall. Facility L reported saving roughly 50 percent on chemical costs, but did not track other cost changes.

"You need to look at how the manufacturing process overall will change. A total process mentality is crucial."
-Shipley Company

Keys to Success
Preventive maintenance is crucial to the success of a Crimson 1®, line, according to all three manufacturers and the vendor. Facility M recommended paying special attention to keeping the fluid delivery systems free of clogs and debris. Other issues included profiling thin-core transport through the system and avoiding variations in water pressure (which can burn out pumps).

Facilities and the vendor also recommended re-evaluating the entire process when adopting the Crimson 1®, system. According to the vendor, "you can't just drop out electroless out and drop in 'Crimson.' You need to look at how the manufacturing process overall will change. A total process mentality is crucial."

For more information on the Crimson 1®, system, contact Hal Thrasher of Shipley Company at 508-229-7594.

Envision DPS™ (Enthone-OMI, Inc.)

The Envision DPS™ method deposits a palladium-tin colloid on the hole during the activation step. A highly alkaline (pH of >12) copper-containing solution at an elevated temperature is used to substitute copper for tin through disproportionation (US patent 5,376,248). Electroplating takes place on the resulting palladium-tin-copper film.

According to the vendor, Enthone-OMI Inc., all but one of the 25 manufacturers using the Envision DPS™ operate it vertically, many in existing electroless copper equipment. Envision DPS™ customers process a variety of board types and dielectric materials ranging from double- sided FR-4 material to multi-layers, Teflon®, and high Tg dielectrics.

Hole diameters of 0.018 inches in multi-layers which are 0.125 inches thick are successfully processed using non-conveyorized (vertical) process configuration. The operation of the Envision DPS™ process in conveyorized (horizontal) configuration improves solution exchange and increases the operating window. Smaller hole sizes and thicker boards are possible.

  • Decreased waste treatment
  • Better hole wall integrity
  • Increased throughput
  • Less use of toxic chemicals
  • Compatible with electroless equipment

Implementation at Specific Facilities
Three facilities (Facilities O, P, and Q) that have successfully implemented the Envision DPS™ process were interviewed for this report. Their motivating factors for switching to the process from electroless copper were environmental compliance, decreased waste treatment and disposal costs, improved throughput, and decreased use of toxic chemicals (e.g., formaldehyde and cyanide).

Facilities O and Q explored carbon and graphite technologies (one facility tested them side-by-side) before adopting the Envision DPS™ system. These facilities mentioned wider operating parameters and improved hole wall integrity as the primary reasons they chose Envision DPSª.

Facility Q also explored a different palladium system, but was discouraged by the up-front investment required to implement the technology.

Installation and debug time ranged from one day for the retrofit of an old line to one month for installation of an entirely new line. All three facilities use the non-conveyorized (vertical) process for all of their board production. Facility Q noted that the Envision DPS™ line was "very compatible" with the old electroless tanks, line set-up, and process. All three manufacturers reported that existing tanks from an electroless copper line were used to some degree, minimizing the need for new equipment purchases and extensive operator training. Additional expenses for line set-up were minor, including an extra filter pump in the catalyst bath, multi-meters, heating element adjustments, and modified pump capabilities.

Experiences with the Envision DPS™ Process
All three facilities encountered minor problems during debugging. At Facility O, hole wall adhesion problems on double sided PWBs were traced back to the drilling step. This manufacturer changed drilling parameters and installed a water blast in their deburring operation to remove loose hole debris. This resulted in improved hole

Facility Q emphasized that line control, lab analysis, and operator training are the most important components of success.

wall quality and eliminated hole wall adhesion failures.

Facility P noted that very large hole sizes tended to void slightly more often than would be expected with an electroless bath. These voids were not seen as a function of poor bath chemistry, but, according to the manufacturer, may have been a result of smears from the drilling process. Manufacturers did not encounter other hole size, board type, or board thickness limitations for Envision DPS™.

Reworked Envision DPS™ panels needed to be treated with slightly more care than reworked electroless panels at Facility Q. When the stripper bath was used to remove dry film, the bath also occasionally removed the palladium from the holes. The manufacturer reran the panels when this occurred.

Keys to Sucess
Each of the manufacturers offered advice for the successful implementation of Envision DPS™. Facility O stressed the importance of drilling quality and consistent copper deposition during plating. Facility Q emphasized line control, lab analysis, and operator training as the most important components of success. Facility P noted that the DPS system is slightly more sensitive than electroless to dirty rinse water and to temperature. This facility found it needed to keep rinses cleaner and to monitor temperature more closely than it had with electroless.

For more information on the Envision DPS™ system, contact Kathy Nargi-Toth of Enthone-OMI, Inc. at 203-932-8635.

HN504™ (Solution Technology Systems)

Solution Technology Systems's HN504ª patented process uses vanillin in the formation of its tin- palladium colloid. Since the vanillin will attach to most surfaces except the surface of other vanillin molecules, the vanillin on the surface of the colloids prevents them from agglomerating. The vanillin also promotes colloid adsorption on the substrate surface, resulting in a conductive layer of palladium. Subsequent treatment in an alkaline accelerator containing copper ions forms a palladium-copper complex with greatly enhanced plating potential.

The HN504™ method can be run as either a non-conveyorized (vertical) or conveyorized (horizontal) system. Approximately 70 percent of the customers using this process run multi-layer boards to some extent. According to the vendor, the HN504™ process has plated hole diameters as small as 0.001 inches, has run an aspect ratio as high as 21:1, and has successfully processed Teflon®,, polyimide, and FR-4 substrates. At one facility interviewed, Teflon®, and certain types of polyimide were processed twice to ensure complete void-free coverage.

  • Elimination of formaldehyde
  • Ease of waste treatment
  • Relatively low system cost
  • Ease of conversion

Implementation at Specific Facilities
Two facilities (Facilities R and S) that have successfully implemented the HN504™ process were interviewed for this report. Their primary motivations for switching to the new process included the elimination of formaldehyde from the process, waste treatment simplification, and the relatively low cost of the new system. Facility R had originally implemented a palladium system licensed from Solution Technology Systems. After running the system for one year and encountering some stability problems with the bath chemistries, the facility decided to "go to the source" of the technology and implemented the HN504™ system. This facility had already tried a carbon system and is currently researching and testing a graphite system to complement the existing HN504™ line. Facility S chose the HN504™ system because of the system's ease of conversion and competitive price. At the time of installation (1990), Facility S believed that the HN504™ process required the fewest equipment changes when converting from an electroless copper line.

Both facilities took one to two days to install the non-conveyorized (vertical) process, with debugging taking up to six months before the system was put into full production. Existing tanks from an electroless copper line were used, which minimized the new equipment purchases required. Heaters, pumps, and filters were installed in the conditioner and accelerator tanks. Also, the conditioner tank needed a stainless steel liner, and the catalyst tank required a water jacket for indirect heating. One facility had unexpected expenses: an electrolytic regeneration unit was needed for the permanganate desmear bath to better control the buildup of manganese, and a dryer was added at the end of the line to ensure that the boards were completely dry. Solution Technology Systems also mentioned that rack agitation and a liner in the accelerator tank to prevent acid leaching from the tank walls may be required at some facilities.

Experiences with the HN504™ Process
Neither facility encountered any problems during debugging, and both thought that the process was very simple. There have been no customer acceptance issues for either facility. Solution Technology Systems stated that some subtle problems can be encountered with the HN504™ process. For example, adding too much conditioner can result in hole wall pull-away. Currently, one facility occasionally observes "smutting" -- an oxide film on the surface of the board -- after the flash-plate as a result of poor rinsing.

Comparisons to Electroless Copper
Both facilities noted that they spend a lot less time on lab analysis compared to electroless copper, since the baths are easier to analyze and need much less attention. In addition, they found that their board failure rates were much lower with the HN504ª process. After switching to the HN504™ process, both facilities simplified their waste treatment because there was much less copper and no chelated wastestreams. Also, both facilities reported a decrease in sludge generation and a slight decrease in water usage with the HN504™ process.

Both the facilities and Solution Technology Systems stressed the importance of training for successful use of the HN504 system.

Keys to Success
The vendor cautioned that the alkaline nature of some of the steps in the Envision DPS™ process may cause problems with alkaline-sensitive adhesives. These issues are similar to those that facilities may experience with electroless copper, but with more pronounced adhesive swelling. According to the vendor, adhesive swelling issues are not a problem in the conveyorized (horizontal) mode due to reduced contact time with the alkaline solutions.

Comparisons to Electroless Copper
All three manufacturers found the Envision DPS™ system more cost-effective than the electroless system they had used previously. They reported spending less time on maintenance and lab analysis while reducing overall cycle time. When asked to compare Envision DPS™ to electroless copper, Facility Q stated: "I know I'm going to save a considerable amount of money." Facility P, noting significant savings in labor and waste treatment costs, called the technology "very cost-effective." The Envision DPS™ system also simplified waste treatment for all three manufacturers. The facilities reported reductions in sludge generation and copper discharge, although overall usage remained constant. Since chelating agents are not used, chelated copper does not enter the wastestream.

Keys to Success
Both the facilities and the vendor stressed the importance of training for successful use of the HN504™ system. The supplier stated that operators need to have the desire and willingness to make the new system work. Both facilities feel that educating operators is very important. They should understand the lab analyses and know what to look for to keep the system operating properly. The facilities also emphasized that operators need to maintain the baths to vendor specifications. The manufacturers noted that this system is fairly simple and does not require special equipment.

For more information on the HN504™ system, contact Eric Harnden of Solution Technology Systems at 909-793-9493 .

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