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SMT electronics assembly manufacturing forum.


Wave-Solder LCDs ???

#2754

Wave-Solder LCDs ??? | 12 October, 2000

This is a question about LCDs (Liquid Crystal Displays) packaged as SIPs or DIPs. My question is: can they be wave-soldered? I found process recommendations on Web pages of several LCD suppliers, and they pretty much all say that LCDs should NEVER be heated in a reflow oven or wave solder machine. Also, caution should be taken when hand soldering, to not overheat the device. However, I have heard from engineers who process them with wave solder machine. So, what is the truth? I know that there are LCD's that are designed for higher-than-standard service temperatures on the product; for example, I found a specification that says: "Extended Temperature Range (-40 to +70�C)" Is there correlation between resistance to temperature in the field and permitted assembly temperatures? Does heat in the assembly process affect product life? What could happen to the LCD?

Any info (datasheets, vendor contacts, etc.) would be helpful.

Thx,

SB

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#2755

Re: Wave-Solder LCDs ??? | 13 October, 2000

We wave no LCD. Irons and pots for soldering.

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#2756

Re: Wave-Solder LCDs ??? | 18 October, 2000

Dave,

who told you not to wave solder? Is it your initiative, just to stay on the safe side, or did somebody provide evidence/recommendation? How could I contact this somebody? Is there any report/datasheet/white paper that you know of?

Thx,

SB

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#2757

Re: Wave-Solder LCDs ??? | 18 October, 2000

Stephano: Our supplier specification sheets define 0 to 50�C operating temperature for most devices. Sheets for other devices to 70(75?)�C. Storage for the first group is 0 to 65�C.

Heck, why don't you float a couple the puppies and check their operation? Wudja loose?

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Greg Amero

#2758

Re: Wave-Solder LCDs ??? | 20 October, 2000

Most LCD manuf. specify not to wave or reflow. I believe this is because of the prolonged exposure to the preheat temp. However, about three years ago, we were running about 350/wk of a 40P DIP LCD through the wave with no fallout. It did stress the display, they would come out solid black, and as they cooled they would clear.

It can be done, but you need to evaluate the long term effects and balance the cost.

Just out of curiosity, I did try one through the relfow. No good. The entire display delaminated.

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Garth Fitzner

#2759

Re: Wave-Solder LCDs ??? | 21 October, 2000

I have been wave soldering LCD's for about five years now and have done many thousands. As someone else mentioned they go dark when heated but then clear as the temp comes back down.

The amount of failures attributable to the wave process has been less than 0.1%.

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Garth Fitzner

#2760

Re: Wave-Solder LCDs ??? | 21 October, 2000

I noticed that my name didn't become an e-mail link. My address is sales@garnetinstruments.com

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#2761

Re: Wave-Solder LCDs ??? | 23 October, 2000

Garth: Do you know how wave soldering has affected the operating life of your LCD?

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