Brian you are correct. The text of the failure report from the component manufacturer says a chloride is present. The EDX printout shows  Cl.
The assembler did not look at the component data sheet when they set up the solder process

Mike B
-------------- Original message from Brian Ellis <[log in to unmask]>: -------------- 


> I obviously cannot answer about the maker's analysis without having read 
> it, but if there chlorine (which is a gas) inside the component, I would 
> certainly want to know why and how, because it is unlikely. OTOH, if 
> they found chloride anions, it is possible that they MAY have come from 
> the flux or any one of another half-dozen sources. Again, I would want 
> to know what the flux manufacturer means 1.5% by weight of chlorine. A 
> typical activator may be, e.g., a carboxylic hydrochloride with a 
> molecular weight in the 100s, of which the chlorine would be about 35. 
> This means the total activator content would be >10%, which is enormous 
> for a halogenated compound. If the activator is an amine or amino acid 
> hydrochloride, the ratio may be even more unfavourable. 
> 
> I'm not saying aye or even och aye, because I do not know. It is 
> possible that the chloride-containing molecules from the flux may 
> penetrate the component, but would this be because the component has a 
> manufacturing defect? 
> 
> From your message, I don't understand that if the manufacturer 
> specifies 0.2% maximum 'chlorine', why your assembler permits the use of 
> one 7½ times the limit. From that alone, I would be suspicious. However, 
> do not assume that this remark implies any blame on anyone. Why? Because 
> I have only a tiny fraction of the knowledge which would allow me to 
> form an opinion and I suspect that there is considerable confusion in 
> places between chlorine and chloride. 
> 
> Brian 
> 
> Mike B wrote: 
> > Thank you Brian for you insight. 
> > No elemental Chlorine�so when I read from the NEC Electronics website 
> and the Recommended Soldering Conditions that �Maximum chlorine content 
> of rosin flux (percentage mass) 0.2% or less� they are meaning a chlorine 
> compound or a chloride. Which makes some sense when I read from a Agilent 
> Versatile Link fiber optic Tech Data sheet which recommends 
> �nonhalogenated .. fluxes (0% chloride)�. 
> > The reason for my initial question was component failures. The company I work 
> for has experienced failures of an opto coupler. The opto coupler component 
> manufacturer found in their analysis chlorine residue in the package . I 
> questioned and suggested the source might be from the encapsulation process or 
> other assembly process which they claimed was not possible because they realize 
> the detrimental effects of chlorine to the wirebonds and leadframe. 
> > The company who solders the printed circuit assemblies uses a flux that 
> contains chlorine (1.5% by wt). Plastic encapsulated IC packages are not 
> considered hermetic, hence the conclusion of chloride in the flux migrating into 
> the IC was a possible cause of the component failures. 
> > Other thoughts are appreciated. 
> > 
> > Mike B 
> > -------------- Original message from Brian Ellis : 
> -------------- 
> > 
> > 
> >> I'll take the example of an SOIC, but you can extrapolate the points to 
> >> other package types. 
> >> 
> >> Firstly, no flux contains elemental chlorine. Some fluxes contain 
> >> organic chlorides or bromides which, under the influence of heat, 
> >> decompose into hydrohalide gases. 
> >> 
> >> Plastics may also contain chlorides or bromides, some added 
> >> deliberately, some there as a result of a prepolymerisation reaction. 
> >> 
> >> Then there is the leadframe: is it clean and burr-free (if stamped) and 
> >> exempt from halides (if plated or chemically etched). 
> >> 
> >> The integrity of a plastic casing around an IC chip is often doubtful. 
> >> It depends on the good flow of the material round the leadframe and the 
> >> adhesion to the leadframe. If either of these is doubtful, then you have 
> >> means of ingress of hydrohalide gas molecules, especially at soldering 
> >> temperature, remembering that there is a stark TC difference between the 
> >> frame and the polymer. Then how porous is the polymer structure itself? 
> >> The hydrogen chloride molecule itself is quite small and can penetrate a 
> >> polymer to a few molecules depth at temperatures above the glass 
> >> transition temperature of the plastic (i.e., above soldering 
> >> temperature), the same as for board substrates. 
> >> 
> >> Various stock phrases of these netlists come to mind: "It depends!", 
> >> "How long is a piece of string?" etc. IOW, there is no hard and fast 
> >> rule because it is up to the IC manufacturer to provide the quality you 
> >> require to minimise the problem or, if it happens, to ensure that it has 
> >> no effect on the IC function over its lifetime. Most of them do a 
> >> reasonable job, but there are variations within a single manufacturer 
> >> from batch to batch, otherwise called working tolerances. The point I 
> >> wish to make is that, even if you use a halide-free flux, you cannot 
> >> guarantee that the manufacturer used the same if the leads are 
> >> hot-tinned. In fact, he probably used a highly aggressive 
> >> chloride-containing water-soluble flux, especially if the leadframe is a 
> >> nickel alloy. 
> >> 
> >> Hope this helps (but I'm afraid it won't!) 
> >> 
> >> Brian 
> >> 
> >> Mike B wrote: 
> >>> Do anyone have information regarding solder fluxes that contain chlorine 
> >>> migrating into plastic IC packages? 
> >>> 
> >>> 
> >>> 
> >>> 
> >> 
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