There is another problem with high humidity. If you are also wave
soldering with alcohol based fluxes with either a wave or foam fluxer
then you can have excessive water pickup by the flux. Fluxes usually
have a water content of around 0.15%, but in high humidity situations
this can climb up to 2%. At these kind of levels you will quite likely
have solder splatter on the bottom of your boards. So, I agree with the
others, if you have a chance to spec in a humidity control system, do
it. Good luck!
Bev Christian
Nortel
>----------
>From: Kathy Palumbo[SMTP:[log in to unmask]]
>Sent: Monday, January 19, 1998 3:06 PM
>To: [log in to unmask]
>Subject: Re: [TN] Assembly Floor Humidity Requirements
>
>We recently relocated to a new building in So. Ca. Our manufacturing
>floor is about 60,000 square feet with a 28 foot open air ceiling. I
>was told, by our facilities department, prior to moving to this location
>that the manufacturing floor would have a $200,000 temperature and
>humidity control system, but when we got here there was none. Needless
>to say our temperature and humidity has been all over the place. When
>the temperature is high and the humidity is up around 70% the water
>soluable solder paste runs all over the place, and what a mess. When
>the humidity is too low the solder paste becomes so dry you can not get
>it to roll properly on the stencil and naturally it doesn't print very
>well. Our yeild went from 99% to 96%.
>
>I have purchased humdidifiers and de-humidifiers to recitfy the problem,
>but this is only a bandaide approach. If you have the chance to spec in
>humidity and temperature control, then do it!! I have spec'd in 35% to
>45% humidity, with the temperature at 68 to 72 degrees F. It will
>definitely save you all kinds of headaches if you have some sort of
>environmental control.
>> ----------
>> From: Juanita Zeinstra[SMTP:[log in to unmask]]
>> Sent: Friday, January 16, 1998 10:30 AM
>> To: [log in to unmask]
>> Subject: [TN] Assembly Floor Humidity Requirements
>>
>> We are located in Grand Rapids Michigan. We are moving across
>> town to
>> a new building which is being renovated to suit our needs. With
>> a
>> tight budget getting tighter, there is a somewhat political and
>> emotional contest in the making.
>>
>> By title our assembly facility will be called the "Engineering
>> Manufacturing Development Center (EMDC)". Engineering activity
>> is
>> located in Grand Rapids, Mi. while production manufacturing will
>> be
>> located in Clearwater, Fla. The EMDC will have process
>> development,
>> low volume and transition responsibilities.
>>
>> We assemble primarily SMT boards but there is some thru-hole and
>> mixed
>> technology as well. Processing in the EMDC includes wave, vapor
>> phase, and hand soldering. IR, convection ovens or even new
>> technolgy
>> soldering may be added later, as well. Our boards are primarily
>> rigid
>> polyimide boards but flex and rigid-flex boards are processed
>> occasionally. Thermount boards are being considered for the
>> future.
>> Cu-Invar-Cu and Cu-Mo-Cu stabilizing cores are frequently
>> employed for
>> CTE stabilization.
>>
>> We will be using more and more plastic and commercial parts and
>> less
>> of the ceramic and military grade parts, as is the industry
>> trend. It
>> also goes without saying that expect to track industry trends in
>> technology, components and processing.
>>
>> We are in the business for the long term. We started our
>> operations
>> in GR in the early 1950's and we will have a 20 year lease on our
>> new
>> facility. Our business niche is high technology commercial and
>> military avionics. Our facility size is almost 900,000 Sq.Ft.
>> and the
>> EMDC and circuit card assembly areas could be as large as 15K-25K
>> Sq.
>> Ft. in size.
>>
>> With that as background, the question is as follows;
>>
>> What temperature / humidity requirements would you recommend for
>> the EMDC and assembly areas of our new facility?
>>
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