Monday, April 30, 2012

Concentration, NVR Testing & R.O.S.E. Testing...What does it all mean to me?

Concentration Readings, NVR Testing & R.O.S.E. Testing...What does it all mean to me?

By Tim Noble

A common topic of discussion is bath management in a PCB defluxing process.  How does one ensure that heir wash solution is in its optimal cleanng state? 

Cleaning systems, i.e. the Aqueous Technologies Trident, come with bath replenishment reminders built in with defaults of 100 cycles, but this is a very generic figure.  It largely depends on what you are cleaning and how quickly the soil you are cleaning will degrade the cleaning capabilty of your wash solution.

When managing your wash solution there are three characteristics that need to be monitored:

  • Concentration
  • Soil Load
  • Cleaning Effectiveness

Concentration is typically measured with a refractometer in many chemistries, and will tell you the concentration of chemistry solution to DI water in an aqueous cleaning solution.  This figure is given on a Brox scale and needs to be converted to concentration by referring to the datasheet for the specific cleaning product.

Soil load testing measures the amounts of soils that are building up in your wash solution tank.  As the wash solution further loaded with soils, the less effective it becomes at cleaning.  This testing method collects samples at intervals and allows you to properly analyze the soil loading of your bath wash solution.  (Please refer to our article on NVR testing.)

Lastly, you need to collect data that will allow you to identify how the oncentration and the soil loading are impacting the cleanliness of your PCBs, so you will need quantifiable cleanliness data on your PCBs.  The easiest way to collect this is via R.O.S.E. (Resistivity Of Solvent Extract) testing.

My recommendations would be to assemble a matrix of Data including the folowing columns:
  • Cycle Number
  • Concentration Reading
  • NVR Test Result
  • R.O.S.E. Test Result
  • Trident (Resisitivity Reading) - If Applicable

I would taking readings at various intervals; i.e. 0 (Control), 20, 40, 60, 80, 100, 120, etc.) at least until you witness a degradation in the cleaning results.  I would assess the data to establish a reliablebath replenishment point.  I would ensure to leave a bit of cushion, for example, if my bath were to degrade at 120 cylces I would leave a 10-20 cycle cushion and set the machine reminder to about 100.

You will notice that I have also tracked the Trident Resistivity reading, and even though this is NOT to be confused with a cleanliness tester, it CAN be valuable as an indicator if something in your process is off.  You possibly can identify a correlation between the other data points and the resistivity reading.

Hopefully thi iformation helps you to manage your bath solution and remember, there is no one specific figure that gurantees success.  You need to monitor multiple figures to ensure that your chemistry is working at peak performance.

Friday, April 13, 2012

PCB Defluxing Process - A True Understanding

PCB Defluxing Process - A True Understanding

By Tim Noble

In order to maximize the results of your PCB/PCA defluxing process, you must truly have a solid understanding of the wash process itself.  All to often batch defluxing equipment gets categorized as dishwashers, when that is truly unfair, the are much more sophisticated in design, the only true similiarity is the appearance of the chamber itself.  In this post, I will cover several topics from the Aqueous Technologies Trident (theory of operation), cleanliness verification and discharge methods.

In the wash process there are 3 main cycles:  
  • Wash Cycle: uses a chemistry solution (approx. 10-25% concentration) to solubulize flux residues that were hardened in the soldering process
  • Rinse Cycle: removal of residual chemistry solution from the PCBs/PCAs
  • Dry Cycle: physical drying process of the PCBs/PCAs, often using forced air in combination with heat
(NOTE:  In the examples in this post I will be referring to the Aqueous Technologies Trident Defluxing System when referencing machine operation.)

Above is a rough diagram of a Trident system and how it operates; below is a step process of how the unit runs its process.

  1. System transfers wash solution from the wash solution tank to the 3.5 gallon sump tank
  2. System heats the solution to your desired temperature (~120-150F)
  3. System pumps the heated solution through the wash chamber for your desired wash time (~5-10 min.)
  4. System "Transfers" the wash solution back to the wash solution tank.
  5. System fills the sump tank with fresh DI water from your DI tanks
  6. System pumps the DI water through the chamber for desired duration (~20-30 seconds)
  7. System takes a resistivity reading of the DI water
  8. System sends DI water to drain/evaporator/recycler
  9. Depending on the resistivity reading the system will either process another rinse process or proceed to drying cycle
  10. If resistivity level is NOT achieved, and MAX rinse count is achieved, system will proceed to dry cycle.
  11. System will use a combination of air and heat to dry your PCBs/PCAs for desired time period
  12. System will end processes with a PASS/FAIL
Resistivity Measurement:

The resistivity measurement is NOT to be confused for a cleanliness test, it simply is a measurement of the discharged water for any type of ionic contamination (flux residue, cleaning chemistry, etc.).  It will not indicate any soils remaining on the PCBs/PCAs. 

What it will tell you is when the chamber has been evacuated of residual chemistry from the wash process, and assuming it has solubulized the flux residues, they should be gone as well.

The theory is that when you fill the system with fresh DI water rinse and if there is any chemistry in the chamber (often in the form of suds) this will be picked up by the resistivity meter and it will proceed to run another rinse cycle.

Often we will run anywhere from 5-10 rinses and a lot depends on the layout of your PCBs/PCAs.

Cleanliness Verification:
As mentioned before, do NOT confuse the resistivity measurement with cleanliness verification.  We recommend using other methods of testing, like the Zero-Ion tester, which uses a solution of IPA to extract residues from the PCBs/PCAs and then divides that by the square area of your PCBs/PCAs, to give you a cleanliness spec.

Most often these types of tests are run as an audit, whether that be one per cycle, one per week, month, etc.  Depending upon how critical of a product you are building will determine how often you verify your process.


Before we make a decision on how we are going to handle the discharge, let's get an understanding of what needs to be discharged.  There are two main types of discharge from a Trident, those are: 
  • Wash Solution Drain
  • Rinse Drain (Primary Drain)

The Wash Solution Drain is only used when you are dumping the contents of your wash solution tank, which may be approximately every 100 wash cycles. 

The Rinse Drain (Primary Drain) is used quite frequently.  It is the discharge after each and every rinse cycle and considering each batch of boards will require approximately 5-10 rinse cycles at ~3.5 gallons per rinse you are looking at about 17.5-35 gallons of discharge (rinse cycle count x 3.5 gallons) per batch.

Now that we have that understood, let's ask ourselves what is important to us?  To our customers?  To our neighbors?  These are the questions that need to be answered when deciding on whether to go green, or exactly how green we are willing to get.  Remember, going green isn't always synomonous with cheap.  But even if you don't buy into green, what about your customer?  What about your local community?  How would they feel that you were saving a dime, at the sacrifice of the environment. 

We all believe we have a responsibility to protect the environment, to the best of our abilities.  Sometimes this means finding ways to incorporate green processes into our manufacturing process.  Difficult for sure, but possible.

As we know, simply dumping the rinse water down the drain is the easiest and the least expensive option for discharge, but it is also the least eco-safe option, and in some municipalities it is outright illegal and becoming more and more scrutinized.

The next solution that came about was evaporation.  In this process they use large boiling systems to evaporate the liquids, leaving the solids behind as a sludge to be removed by your waste hauler.  The cons to this method are:  energy intensive and more scrutinized by REACH (which regulates and emissions out of a vent stack).

Recent developments have been Rinse Water Recycling systems, which basically process the discharge through a set of DI tanks to repolish the water and return it for use.  The system is truly Zero Discharge, with no ventilation and no drain required.  The Cons are the DI tanks do cost money to replace.
You should make sure that your method of discharge is capable of keeping ahead of this discharge volume, otherwords you will be creating a bottle neck in your process.  Please refer to our Rinse Water Recycling vs. Evaporation worksheet, which can be found here for further information.  As you will notice, the Evaporators are limited by capacity and evaporation rate.  Once the evaporator is filled, your wash process is down and that is costing your process money and time.

Obviously direct to drain has no bottle neck on your process, but it is also the least environmentally friendly option available.  As mentioned, you have to be committed to be green as the costs are not always cheap.  But knowing that I am doing as best as I can for the environment is what gives me comfort in my decision.

How do I determine bath life of a cleaning chemistry?

Determining the Bath Life of a Cleaning Chemistry

By Tim Noble

With the development of newer chemistries, in order to meet the needs of the complexity of solder fluxes and soils that we find on our assemblies in today's industries, we are coming across some chemistries that are promoting long term bath lifes, almost implying that bath lifes are infinite. 

I personally do not find any chemistry to be infinite considering that as we clean, soils are loading in our wash solution and similiar to washing dishes, the longer you wash with the same water, the more loaded with soils (dirty) the wash solution becomes.  At some point you need to believe that if the soils outnumber the cleaning composition of the chemistry the effectiveness of the cleaning chemistry will be compromised.

So that brings us to how do we determine bath life of a chemistry?  I refer to an article by Tim Wright, which can be found on our website ( which discusses the proper method for Non-Volatile Residue (NVR) testing.  In a nutshell, this covers collecting samples from your wash solution tank at various intervals (0, 25, 50, 75, 100, etc.) and evaporating all the fluids, which will leave any solids in the collection cup.  This will show you how much soil is collecting in your wash solution tank.

Tim Wright Article:

Taking this a further step, if you perform Ionic Contamination testing (i.e. Aqueous Technologies Zero-Ion Tester) on your circuit assemblies at the same intervals, you should be able to determine at how many wash cycles of a bath, that you witness degradation of your wash performance.  This will help you to identifiy how frequently you will need to change out the chemistry solution in your wash solution tank.

Aqueous Technologies Trident Training Guide

Aqueous Technologies Training Guide

By Tim Noble

I have personally assisted with several installations of the Aqueous Technologies Trident Defluxing system and have gained key knowledge on the process.  Even though each process and installation, will bring different challenges to the table, there are certain factors that are common across many installations. 

I have assembled information that you may find useful when initializing an Aqueous Technologies Trident.  I have also merged this with information from Kyzen Corporation, which as a leading manufacturer of cleaning chemistries, they compliment the cleaning system very well.

The training guide can be located at:

Please feel free to contact me if you have any questions on any of the material.

Wednesday, April 11, 2012

What are your soldering irons costing you?

What are your Soldering Irons Costing You?

By Tim Noble

Often we find that  the hand soldering process, is not a process that gets much attention.  Very frequently customers simply use what systems they have, with the thought that they don't want to invest more into the process, or that they have other processes that require more attention.  Often a large hurdle in an iron evaluation is current inventory of tips, accessories, etc.  This is cumbersome and challenging, but at some point the leak should be fixed.  It is a difficult decision to make, considering the large investment that has been made into the current inventory of stations.

Furthermore, even when the hand soldering process does become a priority, we find that often the first consideration is initial price.  We believe that this can be a very costly mistake to make and we urge our customers to reconsider this strategy.

There are many things that should be taken into consideration when evaluating a hand soldering station and certainly the initial cost of the system is high on that list, but often it's not the only thing that should be considered.  Some others include:

  • Tip Cost & Tip Life
  • Power & Performance
  • Ease of Use & Convenience
  • Process Efficiency

The Ersa i-Con is one of the most technologically advanced soldering stations on the market today.  We don't see many arguments against that statement, but what we do receive is that it is just too expensive.  That the list price of $445.00 is simply too costly to justify, so the customer continues to spend money on their existing stations, which are less advanced on more costly in the long run!

What Ersa costs upfront, they quickly make up for on tip savings.  They maximize efficiency and power, to increase the Iron (Fe) plating on their tips.  In most cases we are achieving approximately 2-3 times the tip life as our competitors. 

This means savings!  When you factor in how much your current stations are costing you in tips and compare that to the Ersa i-Con system, you truly will realize that your systems are in fact costing you....more than you may think.  Tips accumulate fast and often they become more costly than the initial investment you made in your soldering irons!

Bottom line is you are paying more, for less advanced technology!  We urge you to give the Ersa i-Con a true evaluation and evaluate the savings it can mean for your process.  We haven't even discussed the technological advances that the i-Con can bring to your application or process.