Technology Information Corporation

The Finger Marking Technique

Print This Page

How to immediately benefit from the Finger Marking Stickers

Marking the fingers of your wave machines permits you to eliminate your fingers as a variable in your board quality.  This simple technique can be implemented on each of your wave machines right now.  It is the critical partner to the measurement and control of your board-to-wave parallelism.  Implementation of these procedures will immediately and significantly lower your operating costs.

Bent, crooked, loose, broken and dirty fingers are an epidemic.  By marking your fingers – by numbering them – you can empower your team to stamp out this plague.

Finger variations are THE leading cause of board-to-wave disparallelism.  Disparallelism is a major factor in many defects, including bridging, skipping, insufficient solder fill, solder balls and icicles.  It is THE major culprit in inconsistent board quality during a single shift, even more common than defects caused by actual solder wave problems.  Remember, boards that sit on a problematic finger may no longer be parallel to your solder wave.  It only takes one bent finger to lift every board that runs on it.

Measuring and controlling your finger consistency allows you to easily eliminate your fingers as a cause of disparallelism.  Attacking parallelism issues identified by your Wave Solder Optimizer becomes easy, because you know which set of fingers to focus on.  Once you have corrected such variations, you will be able to quickly identify the real source of any remaining or future parallelism problems, such as those caused by your rail, solder pot, nozzle, etc.  For a discussion of the causes of disparallelism (other than finger variations), go to the Daily Parallelism Measurement page.

In fact, the most persistent, difficult, defect-causing finger variations are imperceptible to the naked eye.  This includes variations of 12, 24 or even 36 mil.  These significant variations will appear insignificant to the naked eye, even if your eyes have their clothes on (gotcha!).

It is critical that you mark your fingers for the entire length of your conveyor.  Since you run your boards on all of your fingers, you must mark them in their entirety, on all of your wave machines.  It is useless to mark only one set of fingers and run your Optimizer only on that one set.  That would mean that day after day you are taking measurements from only one set of fingers while at the same time running your boards on all of your fingers.  This is a common mistake because although parallelism data is acquired it still leaves your boards victim to disparallelism due to finger variations.   To verify the integrity of your fingers, your Optimizer must over time acquire data from ALL of your finger sets.  This is very easy and need not be done all at once.  In fact, most engineers measure their fingers on a rotating basis over time.  A Finger Set Tracking chart is available to let you  easily achieve this.  You’ll find it in the print version of this page.  Simply click the PRINT button at the top of the page.

The elimination of bent, crooked, loose, broken and dirty fingers as a factor in your boards’ parallelism to the wave allows you to move on to high impact, daily wave solder process control.  This includes the following fundamental sequence for world class wave solder quality:

(1)  Establishment of Parallelism
(2)  Control of Immersion Depth
(3)  Optimization of Dwell Time by Board Type
(4)  All in conjunction with your Optimizer’s daily verification of your temperatures and
fluxer performance

Procedure to Eliminate Finger Variations as a Cause of Defects

Step 1   Mark Your Fingers in Numbered Groups
a.  If your Optimizer includes the Flux Distribution Window upgrade, apply the stickers in sequence to a finger approximately every 16 inches.
b.  If your Optimizer doesn’t have this capability, then apply the stickers in sequence to a finger approximately every 13 inches.
c.  The stickers should be applied to the TOP ledge of the finger (not the side of the finger) to prevent contact with flux and solder.  Number your fingers in sets of 16 (or 13) inches over the entire length of your conveyor.
d.  To ensure that the sticker adheres properly to the finger you will put it on, you must clean off any residue or dirt that may be on the top surface of the finger!
e.  Now it’s time to run your Optimizer.

Step 2   Running Your Optimizer
a.  Run your Optimizer through your wave machine as usual.
b.  Document which finger set # your Optimizer ran on.
c.  Record your parallelism reading.

Step 3   When You have a Parallel Reading
a.  If your parallelism reading is between 0.2 seconds and –0.2 seconds…Congratulations, you’re within the conventional upper and lower limits!
b.  When you run your Optimizer on the same wave machine again – later in the same shift or on the next shift – follow the same procedure as (a) through (c) in Step 2, except run the Optimizer on a different finger set #.
c.  Continue to carefully document the finger set #’s on which you run your Optimizer.  (It will be simpler for you to do this in numerical order.)
d.  By recording your parallelism readings and the finger set #’s used each time you run your Optimizer, you successfully document that your boards are being run parallel to your wave AND that your fingers are intact.
e.  This is a unique form of continual finger maintenance.  It pays off big, saving you money, downtime, troubleshooting and aggravation when you do have a disparallel reading.

Step 4   When You Have a Disparallel Reading
a.  If your parallelism reading is 0.3 seconds or more or –0.3 seconds or less…Congratulations, you have identified an important disparallelism!
b.  Now, follow the procedures reflected in the scenarios below.
c.  We have presented several scenarios to illustrate how you can respond to different sets of data.

Scenario 1

In this scenario Marla, one of your operators, runs your Optimizer at the beginning of the shift on finger set #1.  Your Optimizer shows a disparallelism, in this example, of 0.5 seconds.

She wants to compare that reading to parallelism readings from three other sets of fingers.  She runs your Optimizer three more times, on three other finger sets (in this example, finger set #’s 2, 3 and 4).

Here are Marla’s results, recorded by her on the accompanying Finger Set Tracking and Parallelism Chart.

Scenario 1 Diagnosis
In this scenario, Marla’s readings from finger set #’s 2, 3 and 4 were parallel (between 0.2 seconds and –0.2 seconds).  This suggests that her disparallelism reading on finger set #1 was due to a finger variation.

Scenario 1 Corrective Action
Finger set #1 was scrutinized for bent, loose, crooked, broken or dirty fingers.  Remember, difficult, defect-causing finger variations can be almost imperceptible to the naked eye.  One finger had solder where the board sits, and another was bent.  The problems with these two specific fingers were addressed.  Next, at 7:55 AM the Optimizer was run again on finger set #1.  The parallelism reading from this run was 0.1 seconds, as reflected below, showing that the corrective action was successful.  Marla is now ready to wave solder your boards.

Scenario 2

In this scenario another one of your wave machine operators, Samantha, runs your Optimizer at the beginning of the shift on finger set #11.  A disparallelism of 0.6 seconds is identified.

She wants to compare that reading to parallelism readings from three other sets of fingers.  She runs your Optimizer three more times, on three other finger sets (in this example, finger set #’s 12,13 and 14).

Here are Samantha’s results, recorded by her on the Finger Set Tracking and Parallelism Chart.

Scenario 2 Diagnosis
In this scenario, Samantha’s readings from finger set #’s 12,13 and 14 were parallel (between 0.2 seconds and –0.2 seconds).  This strongly indicated that your disparallelism reading on finger set #11 was due to a finger variation.

Scenario 2 Corrective Action
Finger set #11 was scrutinized for bent, loose, crooked, broken or dirty fingers.  Remember, difficult, defect-causing finger variations can be almost imperceptible to the naked eye.  In this instance, there were no visible finger problems found.  Therefore, Samantha performed the finger maintenance procedures per the guidelines set forth by your wave machine manufacturer, on finger set #11 only.  (It was not necessary to perform a time consuming, expensive, full finger maintenance exercise on all fingers along the length of your wave machine).  Next, at 3:51 PM your Optimizer was run again on finger set #11.  The parallelism reading from this run was 0.1 seconds, showing that your corrective action was successful.  Samantha is now ready to wave solder your boards. 

Scenario 3

In this scenario David, your newest operator, runs your Optimizer at the beginning of the shift on finger set #21.  Your Optimizer shows a disparallelism, in this example, of 0.7 seconds.

He wants to compare that reading to parallelism readings from three other sets of fingers.  He runs your Optimizer three more times, on three other finger sets (in this example, finger set #’s 22, 23 and 24).

Here are David’s results, recorded by him on the Finger Set Tracking and Parallelism Chart.

Scenario 3 Diagnosis
In this scenario, your readings from finger set #’s 22, 23, and 24 were consistently disparallel at around 0.7 seconds.  This strongly indicated that your disparallelism reading on finger set #21 was not due to a finger variation, but an actual machine problem.

Scenario 3 Corrective Action
A carpenter’s level was used to check your rails and your solder pot.  This showed that your solder pot was not level.  It was then adjusted accordingly.  Next, at 8:53 AM David ran your Optimizer again on finger set #21 to confirm that your solder pot was the only cause of your disparallelism.  The parallelism reading from this run was 0.0 seconds, showing that your corrective action was successful.  For additional verification, David ran the Optimizer on finger set #24.  As you can see below, this produced a parallel reading of 0.1 seconds.  David is now ready to wave solder your boards.

Revolutionary

These scenarios illustrate a monumental achievement in wave solder process control and the opportunity to permanently lower your operating costs.  You now know “The Secret Technique of Marking Your Fingers.”  It should immediately and forever change the way you approach wave soldering every day.  Remember, every board that is run on a set of problem fingers is more likely to have quality variations.  You can now easily solve this problem by eliminating your fingers as a variable in your board quality.

To request the special, numbered stickers for marking the fingers of your wave machines, free of charge, go to the Contact Us page to place your order.

 

“Prior to investing in the Optimizer, we relied on a thermal profiler but we could not solve our skipping and insufficients problems.  In fact, those defects were not due to improper temperatures at all but instead to how our boards run through our solder waves.”

– Ricardo Soto, Process Engineering Manager, Tyco

“The Optimizer identified the root cause of chronic skipping on our boards.  We eliminated the disparallelism it measured.  This had an immediate, positive effect on board quality.”

– Aldrina Paredes, Training manager, Bose Electronics

“We thought we had tried everything possible to eliminate a bridging problem.  Using the Optimizer, in only a couple of minutes we got rid of the bridging completely by adjusting the dwell time.”

– Alfred Santilla, Wave Solder Supervisor, Universal Lighting

“Your wave soldering seminar gave us concrete methods and procedures completely different and beyond anything we’ve ever heard or seen from other vendors or ‘experts’.”

– Juan Guevara, SMT and Through Hole Manager, Alps Automotive

“Your instructor solved our excessive solder and bridging by adjusting our process based on our Optimizer’s data, and showed us how we can easily do this by ourselves.”

– Gary Wirth, Production Supervisor, Honeywell

“Our main problem was recurring insufficients.  We made many attempts to address the problem, to no avail.  By using the Optimizer to graph our immersion depth, we identified and corrected turbulence in our main wave.  This has benefited our production process.”

– Jose Martinez, Maintenance Engineering Supervisor, Rain Bird

“The Optimizer made us re-think how we should wave solder.  We shouldn’t blame the board design as often and we cannot rely on a thermal profiler to control our wave process.”

– Martin Orozco, Process Engineer, TRW Automotive

“Using the Optimizer’s techniques every day on one board type, we saved 257 hours of touch up and rework per month.  This saved our facility over $50,000 in 12 months on this one board type alone.”

– John Lanferman, Process Characterization Group Leader, Celestica

“Your company walked in here and quickly showed my staff how to reduce defects that we’ve had to live with for a long time.”

– Dennis Herrick, Director of Operations, Condor

“Many of our voids and insufficients were assumed to be design defects.  Your training instructor used our Optimizer’s measurements to make adjustments easily and now we should never see these defects in our production again.  What a relief!”

– Enda Moran, manufacturing Manager, CEL

Contact Us