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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


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Yannick

#18598

Profile | 8 January, 2002

Hi,

I experience some trouble with my solder joint recently. And I'm wondering if someone could help me with this. First I use a thermocouple wich I must tape to the board to profile my temperature. I want to buy the Temprobe from Saunder Technologie does anyone already try it?? is it good??

And does someone have a good step by step system to solve soldering problem...I try many thing but when I found a solution for a problem a make a new problem...sometimes I have solderball, other time is splattering, and so on...

Thank you Yannick

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#18605

Profile | 8 January, 2002

You didn�t identify the type of tape you use, but Kapton or similar tape is not an effective method for attaching thermocouples. Search the fine SMTnet Archives for alternatives and comparison of methods.

Two methods for mechanically attaching thermocouples represent extreme opposites - paper clips and screws. The third is Temprobe, a mechanical thermocouple support device, designed expressly to provide quick, reliable temperature readings on any type of surface. PRO: *� Paper clips are certainly quick and easy and will repeatedly withstand oven temperatures. * Screws provide a very rugged and reliable thermocouple attachment and will repeatedly withstand oven temperatures. *� Temprobe is quick and easy to clip the mechanical thermocouple support device to the edge of a board, and to position its thermocouple tip anywhere on the board, even in tight spaces between components. *� Temprobe spring tension holds the thermocouple tip of the device firmly in contact with any type of surface, to sense its temperature accurately and reliably. *� Low thermal mass Temprobe thermocouple tip provides the quick temperature response of a carefully soldered thermocouple. *� Temprobe device requires no bonding. So, there is no board damage, and removal takes just seconds. *� Temprobe device has a small diameter tip. So, it can easily be inserted through a small hole in a component body to measure die temperature. CON: *� Paper clips generally limit you to monitoring near the edge of the board. *� Wire clips do not provide a secure, reliable thermocouple attachment. If the wire is accidentally pulled during handling, it can move the thermocouple. *� Heavy duty spring type clips hold the wire more securely, but their thermal mass and IR shadowing effect can impede the normal heating of the section of board inside the clip. *� Screws obviously damage the board. Also, their thermal mass, and heat conduction from the opposite side of the board and/or internal copper layers can distort the indicated temperature. * Temprobe is expensive, relative other thermocouple attach methods.

Temprobe tricks are: * Probes have some spring to them, so make sure they held down firmly in place near where you want it, then tighten the clamp. * Make sure the probe is mounted on the clamp so that the tightening motion is towards the probe tip to apply some spring tension (otherwise the tip could tend to lift during tightening). * When placing the tip, start beside the pad so as not to disturb the part when tightening the clamp. The tip can then be moved over to the pad. With a little spring pressure applied like this you will not get any false readings and not have to worry about taping down any wires across the rest of the board.

On your soldering problems, we have discussed problems like you mention on SMTnet in the past. Search the fine SMTnet Archies for background. Further, as always, we will be pleased to help you sort through these issues.

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Joe

#18608

Profile | 9 January, 2002

I find the most reliable method is soldering the thermcouple to the joint or between the pin and pad. One thing to take care of is not to use to much solder, which would increase the thermal mass.

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Dreamsniper

#18626

Profile | 10 January, 2002

I'm using Kic Profiler and aluminium tape from Kic and thermocouples from Kic. They are good and reliable. I even manage to modify my heller 1088 by adjusting the fix conveyor and re-baffling the oven. Had dropped my 20-22 deg. C delta T down to 4.3 deg. C. Most of my profile are now having a delta T of between 2.1 deg. C to 6.8 deg. C. Heller' specs is 7 deg. C + and - 3 deg. C. All with the help of my SlimKIC profiler. I love my KIC !

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#18645

Profile | 14 January, 2002

Hi Yannick

A lot of things can cause solder balls and spattering. Such as a to steep preheat profile and to much solder present.

Check out more info on: http://www.smtinfocus.com/smt_failure_list.html

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