Reflow of SMT Glue / Adhesives

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Hi Guys, I need your opinion here. Has anyone tried doing... - Jun 17, 2003 by

Q1: Will the glue's bond strength will be affected? A1: May... - Jun 17, 2003 by davef

We have a line that is double sided reflow and reflow/wave d... - Jun 18, 2003 by

Dreamsniper

#24844

Reflow of SMT Glue / Adhesives | 17 June, 2003

Hi Guys,

I need your opinion here. Has anyone tried doing this Process:

Bottomside Process first which means gluing the chip components then reflowing the Glue instead of Curing them, then Topside process which is solder paste printing then component placement, then reflow process again. The last process is the PTH assembly which means Wave Soldering the PCB. The reason of this process is that we are using a Vapor Phase Process that has no IR preheater but the Maximum Temperature that we get (bec of the Heat Transfer Fluid) is 200 deg C +/- 0.2 degrees across the board. And no matter how big or small the components measured my Delta T is only 0.2 degrees C which is very very good.

Now the query:

a) Will the glue's bond strength will be affected? Most glue manufacturers we asked mentioned that their glue will be able to withstand 300 deg. C for 10 secs. but they can't give me any referral to whose doing this process.

b) Will some of my Ceramic Caps crack during the wave soldering process because of the heat? This i have to see but your opinion is welcome.

c) Can you see any possible problems that I might encounter during this experiment?

Please give me your opinions, feedbacks and queries so I could be able to look into them during the experiment.

Thanks

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davef

#24853

Reflow of SMT Glue / Adhesives | 17 June, 2003

Q1: Will the glue's bond strength will be affected? A1: Maybe. It depends on the glue. Loctite says the rate of cure affects strength => Higher that recommended is more brittle.

Look here: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=17906

Q2: Will some of my Ceramic Caps crack during the wave soldering process because of the heat? A2: Probably

Q3: Can you see any possible problems that I might encounter during this experiment? A3: Glass diodes sometimes don't adhere to glue well. Glass diodes sometimes crack in the wave.

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blnorman

#24867

Reflow of SMT Glue / Adhesives | 18 June, 2003

We have a line that is double sided reflow and reflow/wave depending on the product being manufactured. We asked Loctite if we could cure our chipbonders with the reflow profile to eliminate having to change oven profiles for each. They said we would have no problems and to date we have experienced none. For structural adhesives, normally the higher the cure temp, the higher the bond strength.

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