OK, NiMH batteries have potassium hydroxide electrolyte which is
particularly bad. It will attack most resins, including epoxies,
rendering them porous. I doubt very much whether you will be able to
recover the assemblies or, if you can, it will cost you more than new ones.
I suggest that your 'busted' chips are because they were powered on
under fault conditions. It seems unlikely that the electrolyte would
penetrate the casings. If it did and the chip bonding was with aluminium
wire, their lifetime would count in seconds, as this metal is literally
eaten away by KOH!
Brian
Anil kher wrote:
> Battery was VARTA - NI-MH. 3.6 V. When we picked up the m/cs they were idle
> for 4 years. Manuf date is 1999. M/c booted and worked and within a few days
> it stopped. Found battery leaked. Yes cleaned within a day or two. Removed
> chips so as not to have all residue going between pin and sockets which we
> could not see. Hot water clean and chk under good NIKON - found card is
> clean. Thought battery faulty and soon it happened on the other card also.
>
> No we find some chips busted , 10V +/- regulator gone, etc. Just wondering
> if there are some devices which will fail when battery liquid is on board
> and power on - with all V of 5 , 10 and 14 +/- which ones likely to fail. Or
> just change all.
>
> Thanks
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Thursday, August 28, 2008 1:01 PM
> To: TechNet E-Mail Forum; Anil kher
> Subject: Re: [TN] what damage can a battery leakage do on a TTL/CMOS
> controller card 1990 vintage
>
> Nasty, but what kind of battery to start with? The chemistry of
> different types can vary enormously.
>
> Inge's advice is probably the safest and surest. Prevention is surely
> better than cure: never keep batteries in equipment longer than the
> "sell-by" date, whether used or not.
>
> If the cleaning is done rapidly after the leak occurs, it should be OK,
> but I would scrap anything that has had more than a week's contact with
> the battery residues. Why remove the chips?
>
> Brian
>
> Anil kher wrote:
>> Hi all
>>
>>
>>
>> Need advise. This has happenned twice in the last 2 months. The battery
>> leaked all over the card (S-M - CNC 45 card no. 45.01.02.3) The m/cs did
> not
>> start the next day.
>>
>>
>>
>> If the card is powered after a few years of storage the battery starts
>> leaking and within a few days it is all over the PCB.
>>
>>
>>
>> We removed the chips and cleaned in Hot water / air agitn and againa nd
>> again. Baked bare card and reloaded chips. NADA. Solvent extarct of bare
> PCB
>> all perfect.
>>
>>
>>
>> Advise if we should change all chips - some TTL, some cmos, memory,
> eproms,
>> etc.
>>
>>
>>
>>
>>
>> Anil
>>
>>
>>
>> Micro Interconnexion Pvt. Ltd
>>
>> D3-12 A, Corlim Ind. Estate
>>
>> Corlim, ILHAS, GOA
>>
>> INDIA - 403110
>>
>> Tel: +91-832-2284337
>>
>> Fax: +91-832-2284209
>>
>> alt. E-mail: [log in to unmask]
>>
>>
>>
>> LEADERS IN GOLD PLATED PCBs
>>
>>
>>
>>
>>
>>
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