Stainless Steel is attacked by anything containing chlorides, the higher the temperature the higher the damage, and the temperature doesn't have to be that high, starting around 100deg on up. Known in the industry as chloride stress corrosion. I bellieve other halides have the same effect. We have restrictions on the type of tape we can use based on the cloroide concentration of the adhesives and binders used, paint also.
pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Wednesday, June 06, 2012 3:07 AM
To: [log in to unmask]
Subject: Re: [TN] 答复: [TN] halides in water soluble fluxes
Stainless steel is attacked by hydrohalide acids. Such acids are found in many fluxes in some form or another, and particularly in water-soluble fluxes. Most manufacturers of such fluxes advise that fluxers using them should be constructed from rigid PVC or, better, polypropylene.
It has been observed that SS cleaning machines made from cheap high carbon metals (e.g. 16/6), using ultra-pure water may form a very light, adherent, red powder deposit when cleaning such fluxes. Use a low-carbon
18/8/2 alloy and/or ordinary DI water and not ultra-pure to cure the problem. This may be due to the hydrohalide acids extracting iron oxide from carbon steels by electrolytic action at a crystal level, after the nickel/chromium oxides are attacked locally, but the literature also mentions the phenomenon without the flux, just ultra-pure water. This is a purely cosmetic problem.
Brian
On 06/06/2012 10:17, Mary LI wrote:
> Hi Joyce
>
> What does the SS stand for in the following text of SS tanks?
> Please give me a reply
>
> Thanks
>
>
> Best Regards
> Mary Li 李桂芸
> Editor 编辑/Southern China
> IPC China
> 深圳市南山区南海大道新保辉大厦27楼 A-D
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>
> -----邮件原件-----
> 发件人: TechNet [mailto:[log in to unmask]] 代表 Joyce Koo
> 发送时间: 2012年2月29日 21:27
> 收件人: Technet
> 主题: Re: [TN] halides in water soluble fluxes
>
> Wow. Have to watch for eating in Chinese Restaurant. HCl content is deadly if not clean on time. Take a coffee break in the mid of process run will causes big problem. It even eats some SS tanks if the acid layer become somewhat lower density than the water. Brown stuff darker than coffee ;-).
> I guess you have to take all the benefit with a grain of "acid"?
>
> Joyce Koo
> Materials Researcher - Materials Interconnect Lab Research In Motion
> Limited
> Office: (519) 888-7465 79945
> Mobile: (226) 220-4760
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Wednesday, February 29, 2012 6:44 AM
> To: TechNet E-Mail Forum; Joyce Koo
> Subject: Re: [TN] halides in water soluble fluxes
>
> Pink Lonco? 3355-20. Actually, I preferred the 3355-ST which was similar but only 15% solids and no pink dye. Marvellous stuff! Did you know that it had as activator glutamic acid hydrochloride? Interesting, because, besides its HCl group, it is also an amino acid AND has a carboxylic acid group, so it's a triple-whammy acid as flux! Its sodium salt is monosodium glutamate for Chinese Restaurant Syndrome. An excess of glutamates has neurobiological effects and may be used to mitigate some forms of epilepsy. Glutamic acid is present in almost all animal and vegetable proteins.
>
> Brian
>
> On 29/02/2012 13:07, Joyce Koo wrote:
>> Pink lonco? It solders everything. As long as you clean it fast, its a beauty.
>> --------------------------
>> Sent using BlackBerry
>>
>>
>> ----- Original Message -----
>> From: Brian Ellis [mailto:[log in to unmask]]
>> Sent: Wednesday, February 29, 2012 02:48 AM
>> To: [log in to unmask]<[log in to unmask]>
>> Subject: Re: [TN] halides in water soluble fluxes
>>
>> You have roused my curiosity, Phil. What are the parts that can
>> withstand halide-free WS fluxes but not halide-containing ones, and why?
>> I could understand it for some chemical sensors but optical??? Have
>> you discussed this with your parts manufacturer? Does he give a
>> reason for eschewing halides or is it aqueous processes that he does
>> not like? What is his view on halide-containing rosin fluxes?
>>
>> Please let me warn you that you would need to re-qualify your process
>> because you may find that the halide-free fluxes may be a lot more
>> difficult to clean, especially with a DI-water only wash. You may
>> find that there may be more corrosive residues on the washed boards.
>>
>> For me, assuming that my thoughts are justified, using your current
>> process with one small modification, perhaps not requiring
>> re-qualification, will fill the bill. That is to have a static bath
>> containing a chelating neutraliser (not a saponifier) between the
>> soldering and cleaning operations. A couple of minutes or so will
>> solubilise any heavy metal halides or organic halides and will "kill"
>> the excess acidity of any WS flux. I used to recommend Lonco 2051-B-3
>> but I think this is no longer available. I think Alpha have one
>> called Rinse-Aid and I suppose Kester, Multicore etc. may have equivalents.
>>
>> Have you thought that many components are supplied with halides galore?
>> Component manufacturers often use halide fluxes for tinning their
>> products, often with little or even no cleaning. Much tinned copper
>> wire uses a zinc chloride/hydrochloric acid flux and the only
>> cleaning is running it through a damp sponge followed by a sponge with a waxy substance!
>>
>> If your components are really sensitive to halide ions, I would say
>> that ion chromatography will be an essential part of your
>> qualification process, no matter which flux you use.
>>
>> Finally, have you thought about using your existing process but
>> adding the sensitive components by hand, soldering with an
>> evaporative halide-free no-clean flux, after cleaning? this may a
>> simple cheap way round your problem, especially if the quantities are small.
>>
>> Brian
>>
>> PS Inge: Thanks for the plug. The IPC were kind enough to allow me to
>> mention the availability of the book on this forum a few months ago
>> but I don't want to abuse their hospitality, other than to say there
>> is now a download version as well as the hard copy. I'm now the
>> publisher as well as the author!
>>
>>
>>
>> On 28/02/2012 21:12, Phil Nutting wrote:
>>> We have some parts that are sensitive to halides in flux, specifically some thru-hole opto devices. We are currently using a water soluble flux that contains halides. In doing some very quick research it looks like the WS fluxes have halides and the NC fluxes do not.
>>>
>>> Is there a halide free WS flux for lead-free wave soldering (foam application)?
>>>
>>> We need the WS fluxes because we currently use a DI water only batch wash system. Washing the boards is mandatory for our applications.
>>>
>>> Thanks in advance,
>>>
>>> Phil Nutting
>>> Design for Manufacturing Engineer
>>> Kaiser Systems, Inc.
>>> 126 Sohier Road
>>> Beverly, MA 01915
>>> Phone: 978-922-9300 x1310
>>> Fax: 978-922-8374
>>> e-mail:
>>> [log in to unmask]<mailto:[log in to unmask]>
>>> www.kaisersystems.com<http://www.kaisersystems.com>
>>> www.linkedin.com/in/philnutting<http://www.linkedin.com/in/philnutti
>>> n
>>> g>
>>>
>>>
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