• Cupric Chloride has the highest etch factor (lowest undercut) of all common etchants known which allows for its simple fine line capability and less chance of undercutting.

Cupric Chloride has very little odor when properly balanced and is ready for use immediately even weeks after non-use.

Use extreme care in unpacking the units from their respective shipping crates. Do not pull on or kink the plastic tubing. Do not drop the white pick-up tubes -- they contain fragile float assemblies. Lift the VIS-U-ETCH units out by the cases only. The valves in the Chemical Section are wrapped individually and not connected to the plumbing fittings. Locate the valve labeled "Acid Valve" and connect it to the rear fitting from the Acid Signet and the glass tubing to the injector. Locate the valve labeled "Oxidizer Valve" and connect it to the front fitting from the Oxidizer Signet and the glass tubing to the injector. Be sure to pay attention to the "Flow" arrow on the valves. The proper direction is from the Signet to the injector. Locate the warning horn and light parts and connect them to the top of the Electronic Section. Line up the arrows on the side of each piece.

Careful thought should be given to the placement of the VUE 5 Electronic and Chemical Sections.

• Access to acid, oxidizer and spent (when used) tanks should be available.

The etcher should have approximately 20-25 pounds pressure to operate the Vis-U-Etch 5 as measured at the input to the Vis-U-Etch 5. If the etcher is NOT pre-plumbed for a regenerative system, proceed as follows:

• Drill and tap for a 1/2" or 3/4" N.P.T. into the etch pump manifold as close to the pump as possible. If not possible, into the top spray manifold or pipe will suffice provided enough pressure can be supplied to run the Vis-U-Etch 5 AND maintain enough pressure on the top spray nozzles.

For the return line, perform the following:

See picture below.

• Drill a 45/64" (3/4" may be substituted) hole and tap with 1/2 inch N.P.T. in etch machine for the VUE about two-thirds the distance away from the pump intake across the etch chamber. This hole should be above the liquid level and the pipe elbowed down into the machine.

For the optional Spent system, perform the following:

• For right angle float assembly: Determine maximum liquid level desired in the etch machine and mount float level switch so that float is one (1) inch above that level. This should be in a "quiet" area of the etch machine where there are no waves from the pump and accessible for cleaning.

Remaining items:

• Connect all hoses as shown, clamping to appropriate support as necessary.

Fill etch machine with water and run to check for leaks at all connections - If there are no leaks, drain water and refill with starter etch. Be sure to prime the acid and oxidizer feed lines in manual mode until flow error lights go out when pumping and input chemistry can be seen flowing through the glass sight tubes between the valves and injector assembly. Then, clear the Input Chemical Failure Alarm circuit. See the Input Chemical Failure Alarm section in this manual for more details.

It is extremely important to setup the ventilation of the etcher properly. During normal operation of the Vis-U-Etch 5 and etcher, very little odor is produced by the etchant and therefore very little ventilation is required. If there is a strong chlorine odor while etching and/or regenerating, calibration is required (see Calibration section). The only time strong, powered ventilation is required and/or desired is when an unbalanced etchant state occurs resulting in the release of chlorine gas.

The proper amount of ventilation to have is just enough airflow to prevent any fumes in the etcher from being released into the etch room atmosphere. It is important to reduce the amount of airflow to a bare minimum due to the fact that a certain amount of water is removed from the etchant in the form of water vapor. If the etcher is left running for long periods of time while not etching any panels, the amount of water in the etchant will be reduced and the baumé will rise indicating an increase in the copper level in the etchant. Under extended periods of time, this could cause solids to form in the etchant. If the etcher is to be left on between jobs for the sake of maintaining the temperature, it is a good idea to limit the running time between jobs to no more than 10 minutes.

In a multi-chamber etcher, it is necessary to have a recirculating pump to enable proper blending of the regeneration chemistry with the cupric chloride in the etcher sump. The proper way to plumb the recirculation pump is to connect the feed to the pump from the front of the first etch chamber and the output from the pump to the rear of the final etch chamber. This ensures that the flow of etchant inside the etcher moves from last to first chamber, opposite the direction of the panels on the conveyor. On occasion, we have seen instances of the recirculation pump being plumbed the opposite direction and this can reduce the effective etch speed by as much as 10-15%. The reason is that most etching occurs in the first chamber(s) resulting in an increase in the amount of cuprous chloride in the first chamber(s), which does not etch. By having the flow of etchant moving the same direction as the panels, the cuprous chloride that forms follows the panels through the etcher, impeding the etch rate. By correctly having the flow of circulation in the etcher sump moving the opposite direction of the panels, you always have the fresh cupric chloride from the last chamber(s) moving towards the panels on the conveyor.

When connecting the Vis-U-Etch 5 to a multi-chamber etcher, it is best to sample from the first or second chamber for the Etch In and return the Etch Out approximately one-half to two-thirds the distance from the Etch In line back towards the last etch chamber (See: Items That Affect Calibration).

DO NOT connect the Vis-U-Etch 5 to the recirculation pump! The flow of etchant through the recirculation pump would have to be drastically reduced in order to provide sufficient pressure to operate the Vis-U-Etch 5.

The correct pump capacity and plumbing size is determined as follows. Select a pump and pipe size capable of moving the entire sump capacity of the etcher through the pump in five minutes or less (i.e., Fifty gallons per minute for a two-hundred-fifty gallon total sump). Too little circulation can result in wider swings in the state of the etchant. Enough circulation ensures the most homogeneous etchant solution and consistent etched results.

The VIS-U-ETCH system uses the principal of light transmission to diagnose chemical changes occurring in the etching solution. These changes are color, density, and turbidity.

When the etchant requires regeneration, the VUE uses a "trial and error" system to determine the correct chemical to add. With a choice of two chemicals to cause regeneration (acid or oxidizer) the VUE will add one, mix it with the etchant, and then look at the results as determined by the output meter. If this were the cure, it will continue to add this chemical until regeneration is complete as determined by the rising input meter. If it were not the cure, it will add the other chemical instead and examine the results. If neither helped, it will alternately add both chemicals. The VUE will never add both chemicals simultaneously in the automatic mode. The VUE system is designed to operate with the etch solution in a "starved" chemical condition (never completely regenerated). As etchant is used, starvation is increased to the point where the VUE becomes activated (as determined by the falling input meter). At this point, the etchant will have become slightly darker. Chlorine gas is generated within the solution and is immediately absorbed by the cuprous to cupric reaction. The VUE unit activates when either the cuprous chloride level becomes higher or the cupric hydroxide level becomes higher or both. Regardless of the condition, the etchant partially loses its clarity and becomes darker. Cuprous chloride is re-oxidized to cupric chloride by the introduction of oxidizer. Cupric hydroxide is dissolved by hydrochloric acid (muriatic acid), which also controls side reactions. In either case, the light cells detect a change in light transmission. The change is indicated on the meters. The oxidizer contains a buffer and catalyst which increases the etch speed and makes the etch insensitive to all but large chemical deviations. There is some lightening of the etch when the VUE adds oxidizer even if it is not needed because of sample dilution - the output meter will rise slightly whether needed or not. If oxidizer is needed, the movement of the meter will be marked. This is not the case when acid is added. If acid is added when it is not needed, the output meter will not react. If it goes negative (to the left), it indicates too much acid is in the etchant.

If etchant is not kept in a "starved" condition and the VUE is made to regenerate too early, the chlorine gas generated cannot be absorbed into the etchant and will be released into the atmosphere. The alternation of both valves back and forth indicates a need for both oxidizer and acid - this generally means the solution is in good balance. As the valves alternate, the output meter will rise momentarily and then settle back. Eventually, one mode will take over and/or regeneration will be complete.

On some machines, cavitation of the pump may cause air bubbles to be pumped with the etch solution through the VUE. These bubbles may be seen at the light cell, especially the output cell. Bubbles, due to variables, reflections, and densities, are viewed as partial opacities and will "fool" the VUE’s sensors. The optional bubble extractor will minimize this problem. In addition, the Bubble Detector will alert the operator to any additional bubbles in the etch solution whose source must be identified and corrected. In the event that the VUE lacks sensitivity or will not operate properly due to bubbles, try the following: install a plastic valve at the etch machine before the filter and bubble extractor. Use this valve to control the pressure to the VUE as directed above. Turn the valve mounted on the VUE to full "on". In extreme cases of bubbles, check the etching machine’s pump for need of repair.

The control of copper quantity in the etchant is pre-determined by the oxidizer. Many variables are associated with each etching machine (evaporation of water, venting, drag-in, drag-out, wash down of the machine, etc.). These will affect copper content in the etchant. Excessive drag-in of water from the rinse tank must be avoided as this will dilute the etchant and cause problems - etch speed will be reduced. Regeneration is exothermic, therefore heat will be developed while etching. Cooling coils are necessary. To conserve water, this slightly warmed water may be used for down stream Rinsing. Do not run excessive water through cooling coils - this is wasteful and cooling efficiency is not increased. A chiller may be desirable or necessary depending upon production levels and etcher size.

If, after etching for a while, the copper content (baumé) increases, verification of the oxidizer solution and/or etcher ventilation is in order. Daily verification of the copper content should be performed using Copper Test Procedure.

The "Acid Low" and "Oxidizer Low" lights refer to the level of chemicals in their respective tanks, not to the quantity of these chemicals in the etchant.

A sludge of an inch or less (cupric hydroxide) will form at the bottom of the etch machine with use. This is normal and must not be removed! This sludge is dissolved to some extent as the VUE adds acid - it acts as a buffer.

The Vis-U-Etch process does not use baumé (specific gravity), acid normality or ORP to determine what is needed for regeneration. We do, however, recommend keeping a baumé hydrometer in the inspection tube for a couple of reasons. The first is the baumé reading at operating temperature will pick a point and stay there (39^o-45^o normal range at operating temperature), unlike ORP / normality systems that fluctuate and keep diluting the etchant with water. The baumé reading is determined by oxidizer concentration, calibration setting, altitude of your location, humidity and so on. This is important in helping you to determine if anything has changed in the condition of your etchant. If that happens, you can anticipate problems and their cures rather than react to them later. The second reason is that with a baumé hydrometer floating in the tube you can easily pull it out and inspect the last drip on the bottom for clarity of the etchant. This aids in verifying the calibration of the Vis-U-Etch. For example, if the etchant is not clear green, regeneration should be taking place. If the etchant is clear green and regeneration is taking place accompanied by a chlorine smell, the calibration is set too low. Adjust both meters slightly higher (1/4 turn on each adjustment) and then check again after etching about 10-15 minutes. This gives enough time for the etchant to adapt to the new setting.

Two items that get discussed any time the conversation centers around etching are etch rate and etch factor. There are many things that affect both but in order to gain a better understanding of how to achieve the desired improvements you want there are a few basics to remember that you can work with.

First we’ll talk about etch rate. We frequently hear the question of how fast is our etchant. To answer this and the etch factor question, I’ll use the same simple illustration. Let’s assume that we have a single fixed nozzle etcher with a fixed tray to set our copper on.

When the copper panel is placed on the tray and the spray is turned on, the area directly under the spray nozzle starts to etch very quickly. In direct testing with this method, a one-ounce copper panel will be etched to the substrate in well under a minute under the spray. What is more important to consider, though, is that the area just _" away from the direct spray contact area, although etchant also flows across it, etches only about half as fast. The main reason for this is that the etchant directly hitting the copper changes from cupric chloride to cuprous chloride and stops etching. In order to continue etching, fresh cupric must be delivered to move aside the spent cuprous.

You can test the etch rate of your etcher under the spray nozzle by placing a copper panel on the conveyor and running it into the etch chamber. Turn on the spray pump (not oscillating) for a given number of seconds and see how long it takes to get to the substrate under the nozzle. This is also a great indicator of how much of your etch chamber is actually etching and how much etching doesn’t happen between nozzles. To illustrate my point, let’s assume we have a three foot long etch chamber with one nozzle every foot. If we compare the etch rate of that etcher with another three foot long chamber with spray nozzles every six inches, you’ll find that the conveyor moves twice as fast to etch the same amount of copper because of the increased spray contact area. During one installation of a new Vis-U-Etch 5, we modified an old etcher by almost doubling the number of spray nozzles per spray bar. Under the original spray pattern, it took the conveyor approximately 112 seconds to finish etching a one-ounce panel. After adding the additional nozzles, the conveyor sent the panel through in just 71 seconds, a decrease of more than 36% of the time needed to finish etching the panel. Many of the latest etcher designs have a marked increase in the number of nozzles per square foot or nozzle density.

The type of nozzles used is very important. Usually, full cone type nozzles etch faster than flat fan type nozzles because they deliver more volume of etchant. Fan type nozzles are becoming more popular though because of the higher etch factors needed.

In order to help remove cuprous from the panel more quickly, oscillating spray bars are often used. If the nozzle density is too low, oscillation can really improve the etch rate. If the nozzle density is as high as possible, the puddling effect of cuprous is less and the difference between oscillating and non-oscillating spray bars is less pronounced.

When oscillation is used, one of the most commonly overlooked items is the rate of oscillation. Oscillation is intended to move the cuprous puddle off the panel as quickly as possible. Depending on the size of the panel and the speed of the conveyor, you must set the oscillation rate so the "wave" of etchant moves quickly off the panel but not too quickly that it gets pushed back on. To set this rate correctly you can do this test. Increase the conveyor speed for some test panels so that some of the copper remains. Start with your oscillation rate at 20 back and forth cycles per minute. Run each panel through the etcher, one at a time, adjusting the oscillation rate by 2 cycles per minute higher between panels. What you will see is the etch rate increases and decreases like a sine wave. Pick the rate that works best for each size and thickness of your panels. Thickness changes the conveyor speed so the oscillation rate can change.

Many etchers are designed specifically to run very thin core material. To prevent cores from flipping up and getting caught inside the etch chamber, various types of top rollers are used. This can create an etch rate problem because the more interference with the spray nozzles the slower the topside etch rate becomes. The bottom is less affected because cuprous doesn’t puddle underneath it just falls off.

If spray pressure is increased, etch rate increases. More pressure means faster delivery of fresh cupric and faster removal of cuprous. This becomes very important when the spaces between the traces on your panel are very small. Now higher pressure is needed to "dig" out spent cuprous and replace it with fresh cupric. Many new etchers can operate as high as 40-50 PSI. The consideration for higher pressure will be limited by the hole sizes of your panels when these are etched. Obviously you don’t want higher pressure breaking the tents and etching the inside of the holes.

If etchant temperature is increased, etch rate increases. Higher temperatures speed up chemical reactions. The only limitation here is in the material the etcher is made of. It is generally best to run the temperature as high as the warranty of your equipment allows without exceeding it. If you are not sure about the cooling capability of your etcher set the temperature lower to be safe. Check with your etcher manufacturer to see what is the maximum recommended operating temperature.

Now it’s on to etch factor. Etch factor is essentially how straight your sidewalls are or how little under cutting is occurring. Etch factor is governed by several things.

The first is the reason you bought your Vis-U-Etch 5 to begin with. Other controllers operate using Oxidation-Reduction Potential (ORP) probes to control oxidizer and conductivity (Normality) probes to control the acid content. In order to function properly, Normality probes generally must have at least 0.5N free acid in the etchant. As you increase the free acid content, the etch factor goes down because having free acid on the panel allows the cuprous that forms to be regenerated on the surface of the copper panel. Since cupric chloride will etch copper in any direction, free acid in the spaces between traces will also etch sideways after regenerating in the space. The Vis-U-Etch 5 uses light transmission to sense changes in the clarity of the etchant. This allows us to operate at <0.04N, effectively zero free acid. At 0N, no regeneration occurs on the panel surface. The only way etching can continue is to spray more etchant from the nozzles.

That brings me to the next point. The direction the etchant hits the panel is one of the most important items in determining etch factor. Two things influence the direction. One is the type of spray nozzle. As discussed in the etch rate part of this article, there are two types of nozzles used, full cone and flat fan. While it’s true full cone nozzles generally deliver more etchant and a faster etch rate, they also spray the etchant at an angle other than 90^o to the surface. Flat fan type nozzles spray much closer to 90^o to the panel surface.

You can try this experiment using the one nozzle etcher I talked about in our first example. Place a thick piece of copper under the spray nozzle. Set the angle of the nozzle at 45^o. Watch how the copper etches. You’ll see that the hole it creates through the panel is approximately 45^o. This is because cupric chloride from the nozzle first hits the panel surface going downward, etching where it contacts. Spraying at an angle means that the path of the etchant through the metal is going sideways too.

The 45^o scenario may sound a little extreme but think about how the oscillation in your etcher works. There are two types of oscillation (when used) found in most etchers.

The first is the swing type. This construction has nozzles mounted to a spray bar that turns back and forth in an arc. This points the spray at the panel within an arc that is only 90^o to the panel at one spot in the arc. This angled spray lowers the etch factor.

The second type is horizontal reciprocation. This method is becoming more popular because the nozzles are mounted to spray bars that keep them pointing 90^o to the panel. The whole rack of nozzles moves from side to side. Since etchant always sprays as close to 90^o as possible to the panel, you get the highest etch factor or straightest sidewalls.

Most things in life are more easily understood when viewed in their simplest form. The single nozzle etcher sounds like a silly idea until you consider that it makes you focus your attention on the most important thing: how the spray contacts the panel.

No adjustment is necessary or provided.

The Input Meter has these functions:

1. Amber ".2" or "Regen" LED indicates when regeneration starts and when regeneration has occurred in relation to the moving bar graph. It does NOT determine what chemical is required for regeneration.

The Output Meter has these functions:

1. Red "Error" or yellow "Off-Scale" LED indicates the output of the light cell is higher or lower than the meter range. This is a normal condition at times.

If color of etchant is still clear emerald green when meters drop to ".2" or "Regen" starting regeneration, calibration setting is too low. Adjust "In" and "Out" calibration potentiometers together slightly higher. If left at this low setting, over regeneration will occur releasing chlorine gas.

If color of etchant turns noticeably darker and etch rate slows before meters drop to .2 or "Regen", setting is too high. Adjust "In" and "Out" calibration potentiometers together slightly lower. If left at this setting, inefficient etching speed and wider swings in the state of the etchant will occur.

If meters are slightly readjusted, etch boards and allow VUE 5 to regenerate several cycles. Recheck to see if the color/clarity of the etchant is clear emerald green with no chlorine smell when the Input Meter reaches the "Cal" point at about _ scale.

NOTE: Proper calibration should be verified every month whether adjustment is needed or not. Large variations in calibration accuracy can cause over regeneration and the release of chlorine gas.

The purpose of this circuit is to prevent the addition of either acid or oxidizer for more than 2_ minutes without needing to be reset.

In automatic mode, if either chemical is continuously added for more than 2_ minutes, the check calibration LED on the motherboard and chemical (Acid or Oxidizer) flow error light will come on. The output meter will drop and the Vis-U-Etch 5 will switch to the other chemical after 7 seconds. This will reset the check calibration circuit. If the other chemical does not cause a sufficient reaction in the output meter, the Vis-U-Etch 5 will once again switch back to the original chemical. This is to check and see if chemical dilution is occurring. If the other chemical does react strongly like the first, most likely the calibration setting is too low or too high and should be adjusted (See Calibration). This would be evident by the check calibration LED lighting every 2_ minutes.

Even if the calibration setting is correct, there will be times when the etchant requires more than 2_ minutes of one chemical. By qualifying this add with 7 seconds of the other (non-reactive) chemical, you are proving the calibration setting to be correct and adding 7 seconds of the wrong chemical will not have any significant impact on the etchant.

In manual mode, the safety of this circuit is even more pronounced. When either acid or oxidizer is added manually, there is no automatic switching between chemicals so the check calibration circuit does not reset automatically either. In order to rest the circuit, both chemical switches must be turned off. Once off, the circuit resets and automatic or manual chemical adds can be resumed. The main purpose of this feature for manual operation is to prevent an etch operator from inadvertently setting the switch to manual operation and then walking away creating a runaway chemical add.

On the motherboard, there is a jumper setting for the check calibration circuit that says "Etcher Size", "Large" or "Small". This is actually the length of the time-out cycle.

For the small (factory) setting, the time-out is the 2_ minute setting mentioned so far. In the case of some installations, the capacity of the selected size of Vis-U-Etch 5 may be only 10% ~ 20% larger than the amount of copper that can be added to the sump continuously. In such cases, it may be frequently required for the Vis-U-Etch 5 to add one chemical for longer than 2_ minutes. This would cause the 2_-minute limitation to be a problem. For that reason, we added the "Large" jumper setting. This increases the time-out to 4_ minutes.

As a precaution, we strongly recommend that you contact the factory before changing to this setting. There may be other issues at work such as etcher circulation (discussed previously) that may indicate a false reason for increasing the time-out setting.

The Bubble Detector circuit is preset at the factory and generally does not require re-calibration. Furthermore, once calibration is properly set no additional adjustments should be needed.

1. Turn the etcher on. After approximately 65 seconds, the VUE 5 will turn on.

The Timed Sequence Circuit is a unique switching circuit that switches modes from acid to oxidizer and back. Since the addition of acid to the etchant is not as apparent in its reaction the circuit will always start in the acid mode first. If acid is not the curing element, as determined by the Output Meter, it will then automatically switch to the oxidizer mode.

Experimentation has shown that greater economy of chemicals is realized by acid first trial and this automatic injection of acid first will occur whenever regeneration is initiated.

Settings for the Timed Sequence Circuit are preset at the factory and can not be changed. If you suspect a problem with the timing cycle, call for technical assistance.

110V-120V AC 60HZ 2.5A. Standard USA Grounded Outlet.

DO NOT use on same circuit as electric motors or with other devices that cause electrical interference.

II. Acid:?Use only water white acid (31%, 20^o Baumé, Fe <1ppm, Sulfates <250ppm).

SODIUM CHLORATE BASED OXIDIZER (NaClO₃) is a powerful oxidizing agent. A fire hazard exists when it is mixed and dried with any oxidizable material such as wood, paper, etc. Instruct ALL personnel handling this chemical of its properties - read the Material Safety Data Sheet supplied with ALL chemicals. There is no longer a fire hazard once the oxidizer mixes with the etchant as controlled by the VUE.

MURIATIC (hydrochloric) ACID is a strong acid. Never mix acid and chlorate, as a violent chemical reaction occurs and an abundance of chlorine gas will be liberated.

As a rule, etchant has very little odor to it; however, powered venting is required. A strong chlorine odor indicates an out of balance chemistry (see: Causes of Chlorine Gassing). If chlorine is detected, turn the VUE flow valve "off". Etch boards until the excess chlorine is consumed and then check for the cause.

DO NOT TURN THE ETCH MACHINE "OFF" WHILE REGENERATION IS IN PROCESS. Allow at least five (5) minutes after all lights go off (except pilot and spent lights) before turning off etch to flush the lines of any concentrated chemicals.

Color code refers to the color of the tie wraps around each wire starting from the connector side of the Chemical Section Internal Wiring Harness.

2. Check Oxidizer and Acid Wye Strainers every time the respective tank is empty for obstructions or debris.

IV.?When replacing any plumbing parts, use silicone dielectric compound only on the O-rings. For threaded pressure switch or other permanent fittings, use 100% silicone sealer. NEVER USE TEFLON TAPE ON FITTINGS. Teflon tape WILL leak and cause operating problems.

Two (2) valves are used for vacuum operation. The spent valve (when used) is the only pressure-operated valve. If any leakage is observed from a valve, replace it. These valves have a custom Teflon® core, available from Oxford V.U.E., Inc., for use with etchant chemicals. Standard valve replacements are not designed for this purpose and will fail quickly.

The chemistry of the VUE system lends itself well to pollution control and great savings of water. For an average etch machine, a 50-gallon open tank placed under the rinse tank with a small recirculating chemical pump will suffice. Fill the tank with water and add approximately one (1) liter of muriatic acid. Drop in pieces of scrap aluminum (not necessarily pure aluminum). As the boards come out of the etch machine, the rinse water will remove the copper and drain into the tank. A reaction occurs that will precipitate copper out as copper metal and the aluminum will go into solution. At the end of the shift, or better, the following day, the liquid may be drained out of the tank and the trapped copper metal removed. This liquid will contain aluminum chloride, which is currently not considered a pollutant. The acid will be consumed. The pump should have a filter before it in order to prevent particles from clogging either the pump itself or the jets.

1. Pipette a 1.0 ml. sample of cupric chloride etching solution into a 250 ml. Erlenmeyer flask. For best accuracy, a "To Contain" (TC) pipette is recommended. After dispensing cupric solution from pipette wipe down the exterior of the pipette and rinse out the interior with DI water into the sample flask-total DI water addition should be approximately 50 ml.

Calculations:

Copper by ounces per gallon =?ml. sodium thiosulfate x 6.354

?7.5

1. Pipette a 1.0 ml. sample of cupric chloride etching solution into a 250 ml. Erlenmeyer flask. For best accuracy, a "To Contain" (TC) pipette is recommended. After dispensing cupric solution from pipette wipe down the exterior of the pipette and rinse out the interior with DI water into the sample flask-total DI water addition should be approximately 50 ml.

In order to regenerate or convert cuprous chloride (CuCl) back to cupric chloride (CuCl₂), chlorine gas (Cl₂) must be added to the etchant. The safest method of chlorine gas addition is to combine two agents in the etchant that produce chlorine gas that is immediately consumed by the cuprous to cupric reaction. This is how your Vis-U-Etch 5 operates. Combined with a sodium (Na) buffer/catalyst, the Vis-U-Etch 5 is the safest and most stable of all systems. There is, however, the ever-present possibility of a chlorine gas event due to improper calibration, mechanical failure or operator error. At the first sign of a chlorine gas smell, calibration and/or mechanical failure should be checked. If corrected immediately, the etchant will remain balanced and no loss of production will occur. If left unchecked, a significant chlorine gas release can occur, stopping production and clearing the etch room of all personnel. In a perfect world, all personnel would read all owner's/procedure manuals and be properly trained in the operation and safety of the equipment they use. Realizing that sometimes things don't go as planned, here is the proper way to handle a chlorine gas event:

1. Turn off the etcher and all equipment except for room/etcher ventilation.

In the event of failure of the VIS-U-ETCH, regeneration may be accomplished manually while repairs are being made.

Obtain two (2) small plastic bottles with squire tops (dish washing soap bottles work fine). Label one "acid" and the other "oxidizer" and fill these bottles with their respective chemicals. When regeneration of the etch is necessary as determined by its darker color (loss of clarity), do the following:

• Take a small sample in a beaker.

?CAUTION: Do not add too much acid as chlorine gas may be liberated.

It is advisable to keep the first barrel(s) of spent etch that is generated so that in the event of catastrophic loss of etchant (incorrectly mixed chemicals, dilution of etch, etc.), the etching machine may be dumped and restarted.

Oxford V.U.E., Inc. herein referred to as the Company, warrants VIS-U-ETCH to be free from defects in material and workmanship under the prescribed installation and under normal use and service.

The Company’s obligation under this warranty is limited to repairing or replacing, at its option, any part or parts thereof, claimed to be defective, which shall, within six (6) months after delivery to the original purchaser, be returned prepaid to the Company. The six months warranty period shall extend to all parts.

Parts which have been modified, disassembled or abused will void the warranty on such parts.

Parts returned to the Company shall be accompanied by a statement describing the problem, the date placed in service and examination of the part shall disclose the company’s satisfaction to have been defective.

This warranty is in lieu of any other warranties, expressed or implied.