With RF signals, not only are resistive losses (low SIR) important, but 
also capacitive losses.  Hence, no-clean flux residues that have good 
behavior with respect to high SIR, may no be as good with regard to 
capacitive losses. 

Karen Tellefsen - Electrical Testing
Alpha / 109 Corporate Blvd./ S. Plainfield, NJ 07080
[log in to unmask]
908-791-3069




From:   Brian Ellis <[log in to unmask]>
To:     <[log in to unmask]>, 
Date:   06/02/2012 02:04 AM
Subject:        Re: [TN] Cleaning PCB Assemblies
Sent by:        TechNet <[log in to unmask]>



I'm surprised that you think Ensolv can even look at no-clean product 
fluxes more than cosmetically. It is based on n-propyl bromide which has 
general characteristics similar to trichloroethylene but is more toxic 
(central nervous and reproductive systems), a suspected carcinogen and 
depletes the ozone layer (the Parties to the Montreal Protocol have not 
entered it in the list of controlled substances but their wording is to 
discourage its use). It cannot be guaranteed to remove all the 
components in your flux residues and it may leave an invisible monolayer 
of one or more of them, some of which may be hygroscopic, which would 
explain poor RF performance.

Have you performed SIR/ECM tests?

As Bev says, cleaning no-clean makes no sense. If you wish to clean (or 
have to), use flux systems specifically designed for easy cleaning. A 
good aqueous cleaner is second to none, as I have stated since the 1960s!

Brian

On 02/06/2012 02:49, [log in to unmask] wrote:
> Hi Folks!!  Could use some help.  We are a contract mfg. using no-clean 
solder paste and roll solder
> for secondary ops and touch-up.  Some of the PCB assemblies contain RF 
components and we have
> had a customer voice some concerns regarding our cleaning (using 
EnSolv).  Have heard that new
> chemistries with a aqueous washing system have been successful.  Have 
also heard a vapor degreaser
> works well but not the greatest choice with RF components.
>
> Would appreciate being pointed in the right direction.
>
> Thanks in advance for your help!!!!!
>
> Regards,
> Bill
>
>
>
>
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