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Subject:
From:
Graham Naisbitt <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Graham Naisbitt <[log in to unmask]>
Date:
Wed, 28 May 2014 17:25:05 +0100
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Joe, Joe, Joe,

Please excuse me but:

SIR / CAF tests will tell you whether your end product might be reliable from an electro-chemical standpoint. They will not tell you what is present causing any problems. They do not discriminate ionic and non-ionic contamination.

IF you encounter a problem, then IC will tell you what is there causing the problem, but it cannot tell you if the end product will be reliable - keeping in mind that there exists non-ionic contaminants.

So, qualify the process using SIR / CAF as appropriate, then use Process Ionic Contamination Testing = PICT, to control the process. As Brian rightly points out, ROSE is a grossly misemployed test. I would love to rewrite it but, as many friends in the industry have pointed out, including you Joe, I will most likely die in the attempt hence I am using the term PICT and starting from that basis. It will appear as an IEC test soon.

Kindest regards

Graham Naisbitt

On 28 May 2014, at 14:36, Joe Russeau <[log in to unmask]> wrote:

> Hello Brian,
> 
> See my responses to your comments below, designated by ***.
> 
> Best Regards,
> 
> Joe Russeau
> 
> ----- Original Message ----- From: "Brian Ellis" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, May 28, 2014 3:12 AM
> Subject: Re: [TN] PCB Cleanliness Via Ion Chromatography Poll (informal)
> 
> 
>> Let me add a couple of eurocents worth.
>> 
>> 1. Ion chromatography is useless for incoming board testing. Far too long and far too expensive. By the time you have the results from a valid sample of a batch (say 1-5%), your board will be obsolete.
> 
> *** Again, I have to disagree that the "tool" is useless for incoming board testing.  It has two very important analytical features that make it applicable.  Those two features are selectivity and sensitivity.  Now I am not saying it is a perfect tool. Like any analytical technique it has its limitations.  However, it is has a tremendous amount of capability if it is properly set-up and the user understands how to apply it AND understands the material sets he/she is evaluating.
> 
> Does it take too long?  Possibly, it depends (Doug just add that to my Mt. Dew tab).  It depends on what too long means.  If your goal is to have an immediate answer then yes it takes too long.  I know many that utilize ROSE to test/control/track incoming board cleanliness because it is quick and gives an immediate answer, but when you ask them how they know the board is clean, I often hear silence on the other end of the phone.  On  the other hand, if your goal is to understand what is present on the surface of your board and what impacts certain ions may have on product reliability, then perhaps the time to test isn't so long.  It really boils down to your goal for testing.  Also, if all your looking for are simple anions and cations, then IC systems can churn those results out in about ten minutes (depending on your set-up).  If organics are in the sample matrix, then more time is going to be needed to evaluate them.  IC is not an immediate answer I'll grant you that, but it gives those that are trying to understand their residue picture more information about it.
> 
> As for expense, it can be expensive depending on who is doing the testing and what is being analyzed.  But keep in mind that part of the expense is paying for the expertise and knowledge.  I know that it is difficult to place a price on that, but hey if it helps someone avoid a process line from being shut down, then the expense of testing is a pittance by comparison.
> 
> 
>> 
>> 2. SIR or ECM testing is useless for incoming board testing. Far too long and far too expensive. By the time you have the results from a valid sample of a batch (say 1-5%), your board will be obsolete.
> 
> *** Totally agree.
> 
>> 
>> 3. IC, SIR and ECM are qualification tests, unsuitable for incoming goods testing. Because of the chemical nature of the surface finishes, it is impossible to extrapolate the results obtained during qualification to production conditions, because there may be slight differences in the stoichiometry of the resins and their various treatments in board manufacture (or even changes of laminate manufacturer) etc.
>> 
> 
> *** My only disagreement with your statement above is classifying IC as a qualification tool.  I would not classify it as such. Why? Because there is a lot of subjectivity between the experts in defining what is considered clean and not clean.  IPC-5704 helps some with incoming board cleanliness by setting up an industry standard that has been mutually agreed upon within committee.  However, no such standard exists for assembly cleanliness and some might be misled into thinking that IC can be used to qualify their products.  I'd say it can help in understanding the residue picture, but I wouldn't rely solely on those results to say all is good.  It provides data into one aspect of reliability.  Other testing may be required depending upon what you are qualifying.
> 
>> 4. In my considered opinion, the *ONLY* practical test for incoming boards in a production environment is ICT (Ionic Contamination Testing), sometimes incorrectly called the "ROSE" test for historical reasons. It is fast, if rough and ready, and will detect the presence of most (but not all) of the harmful contaminants and bad stoichiometry of resins, without necessarily identifying them (some testers will give indications of the causes of problems by software analysis). Don't underestimate this valuable tool.
> 
> *** No comment.
>> 
>> Brian
>> 
>> 
>> On 23.05.2014 16:27, Richard Kraszewski wrote:
>>> I actually sent this out on May  16th, but never got a single response. Hoping that was not due to lack of interest, but rather due to the TechNet being down. Hence, I think I'll try this one more time.
>>> 
>>> I am  hoping to run an informal " min straw poll " here.
>>> 
>>> Questions stated  are as follows:
>>> 
>>> 
>>> 1.       "Is your organization testing  incoming  PCB cleanliness  via ion- chromatography?             Replies such as "YES" or "NO" will suffice, but more detailed explanations are also acceptable.
>>> 
>>> 
>>> 
>>> 2.       " If testing via IC, do you use IPC -5704 Table 4.1 limits or other?                                                Replies such as " IPC"  or "other"  will suffice, but more detailed explanations are also acceptable.
>>> 
>>> What's in  it for  you?   I will summarize and post the results after a few days of replies.
>>> 
>>> Rich  Kraszewski
>>> Senior Process Engineer
>>> Plexus
>>> 
>>> 
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