Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Controlled TempHumidity rooms

Martin J. Ibarra

#13315

Controlled TempHumidity rooms | 9 December, 1998

Hi, I know for sure that by controlling temp. and humidity conditions in SMT assy lines room, one gets advantage in screen printing, adhesive dispensing, and pick&place machines mainteinance. Does any one have any advice on why else is a clean room required for SMT processes? Thx.

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Earl Moon

#13316

Re: Controlled TempHumidity rooms | 9 December, 1998

| Hi, I know for sure that by controlling temp. and humidity | conditions in SMT assy lines room, one gets advantage in | screen printing, adhesive dispensing, and pick&place | machines mainteinance. Does any one have any advice on why | else is a clean room required for SMT processes? | Thx. | PCB and stencil dimensional stability, reduced oxidation, improved/measurable/manageable solder profiles, longer PCB solder termination area/solder paste shelf life, moderated PCB and chip device TCE matching, cleanliness, flux preservation and activation, etc. The etc. means what T/H controls do your plan to employ and how clean do you want to keep the room as clean rooms aren't always temp/humidity controlled - and much more. Good question as we're headed this way.

Enjoy,

Earl Moon

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Dave F

#13317

Re: Controlled TempHumidity rooms | 9 December, 1998

| Hi, I know for sure that by controlling temp. and humidity | conditions in SMT assy lines room, one gets advantage in | screen printing, adhesive dispensing, and pick&place | machines mainteinance. Does any one have any advice on why | else is a clean room required for SMT processes? | Thx. | Martin: We often quantify the effect of controlling T&H by illustrating improvements in process control. And that makes sense. But a more difficult, and some may say more important, measure is the effect of a comfortable work environment on the productivity of our people. The juice that makes an assembly shop go.

In defining the limits of allowable temperature and humidity, you might also consider limiting the rate of change in temperature and humidity. Like:

1 The temperature should be maintained in the production area between 18�C and 25�C with no more than a 3�C change per hour.

2 The relative humidity should be maintained in the production area between 65% RH and 30% RH. The relative humidity should be maintained at the desired setting with a maximum tolerance of 10% swing.

TTYL

Dave F

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phillip fhunter

#13318

Re: Controlled TempHumidity rooms | 9 December, 1998

| Hi, I know for sure that by controlling temp. and humidity | conditions in SMT assy lines room, one gets advantage in | screen printing, adhesive dispensing, and pick&place | machines mainteinance. Does any one have any advice on why | else is a clean room required for SMT processes? | Thx. | A controlled atmosphere room (environmental chamber) is not necessarily a clean room (mutually exclusive). One Controlls factors like temperature and humidity. The other controlls particle size and distribution per unit volume. It would be great to do both in an SMT shop! The effects of temp. / humidity controll are obvious for solder paste but it also offers dimensional stability for the P&P process. Also, as feature sizes shrink the effects of contamination become a greater factor. This is the primary benefit for a "clean room". I worked in a class 10K clean room. From a technicians point of view when you have to crawl around on the floor to repair a machine its great to not come up looking like a dust mop!

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