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Ceramic + Hi-temp solder

Michael N.

#11819

Ceramic + Hi-temp solder | 21 April, 1999

I'm having problems with trying to get a good solder joint using a Ceramic PCB. We are using AMTECH hi-temp solder (ws-486 96.5/3.5ag). My profile looks great and I used the recommended profile from Amtech with a few adjustments. My max temp is about 250c. We have no problem with using the FR4 board, but the ceramic is sometimes having cold solder joints. We are using a 7 zone oven, soem joints looks good on the plcc and some have cold solder. We are also using a carrier made of compressed rock/stone from Stone Mountain Tool..I have no experience in using Hi-Temp solder paste or ceramic, I would appreciate any help I can get...Thanks!!!!

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#11820

Re: Ceramic + Hi-temp solder | 21 April, 1999

| I'm having problems with trying to get a good solder joint using a Ceramic PCB. We are using AMTECH hi-temp solder (ws-486 96.5/3.5ag). My profile looks great and I used the recommended profile from Amtech with a few adjustments. My max temp is about 250c. We have no problem with using the FR4 board, but the ceramic is sometimes having cold solder joints. We are using a 7 zone oven, soem joints looks good on the plcc and some have cold solder. We are also using a carrier made of compressed rock/stone from Stone Mountain Tool..I have no experience in using Hi-Temp solder paste or ceramic, I would appreciate any help I can get...Thanks!!!! | Michael: More information would be helpful.

1. Is the item that solders well the same as the item that solders poorly (less attractively)? 2. Was failure analysis performed? And if so, what was the result? 3. Has the manufacturer been contacted, provided samples of failed items, and provided a response? 4. Is the failed item from a single lot or from various lots? 5. Is the failed item from a single manufacturer or from various sources? 6. Is the failed item being used within the environmental and functional limitations of its specifications? 7. What is the history of this design? (is this a new product)? 8. What makes you so comfortable that the profiles you report are accurate?

As a flier, sometimes PLCCs from different suppliers have different solderability protectant materials on the component leads and reaction of these different materials with the solder can create different visual effects.

Good luck

Dave F

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#11821

Re: Ceramic + Hi-temp solder | 21 April, 1999

| I'm having problems with trying to get a good solder joint using a Ceramic PCB. We are using AMTECH hi-temp solder (ws-486 96.5/3.5ag). My profile looks great and I used the recommended profile from Amtech with a few adjustments. My max temp is about 250c. We have no problem with using the FR4 board, but the ceramic is sometimes having cold solder joints. We are using a 7 zone oven, soem joints looks good on the plcc and some have cold solder. We are also using a carrier made of compressed rock/stone from Stone Mountain Tool..I have no experience in using Hi-Temp solder paste or ceramic, I would appreciate any help I can get...Thanks!!!! |

If your ceramic board had Paladium silver conductors, I think I know what is going on. I solder to thickfilm hybrids everyday and I need to run my product right on the edge of reflow. I use 62/36/2 solder which melts at 179 C. My time above reflow is about 20 sec with a max temp of 195 C. When I had an IR oven, I had what appeared to be cold solder joints. However, they were not cold. They were overheated joints. Forced convection oven gave me even heat across the ceramic board. However, if my profile was too hot on the forced convection oven, I got what appeared to be cold solder joints. What else I notice when soldering to paladium silver conductors it that too little solder leaves a grainy dull solder joint as well. I believe this occurs due to silver being present in the solder joint from the conductor. The greater the amount of solder deposited the less percentage of silver in the solder joint. The hotter the profile the faster the silver conductor disolves into the solder. I am not sure this is what you are experiencing but too much heat when soldering to paladium silver will cause what appears to be cold solder joints.

Good luck and let me know if you are soldering to paladium silver and if you fix the problem.

Chris

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Michael N.

#11822

Re: Ceramic + Hi-temp solder | 22 April, 1999

| | I'm having problems with trying to get a good solder joint using a Ceramic PCB. We are using AMTECH hi-temp solder (ws-486 96.5/3.5ag). My profile looks great and I used the recommended profile from Amtech with a few adjustments. My max temp is about 250c. We have no problem with using the FR4 board, but the ceramic is sometimes having cold solder joints. We are using a 7 zone oven, soem joints looks good on the plcc and some have cold solder. We are also using a carrier made of compressed rock/stone from Stone Mountain Tool..I have no experience in using Hi-Temp solder paste or ceramic, I would appreciate any help I can get...Thanks!!!! | | | Michael: More information would be helpful. | | 1. Is the item that solders well the same as the item that solders poorly (less attractively)? | 2. Was failure analysis performed? And if so, what was the result? | 3. Has the manufacturer been contacted, provided samples of failed items, and provided a response? | 4. Is the failed item from a single lot or from various lots? | 5. Is the failed item from a single manufacturer or from various sources? | 6. Is the failed item being used within the environmental and functional limitations of its specifications? | 7. What is the history of this design? (is this a new product)? | 8. What makes you so comfortable that the profiles you report are accurate? | | As a flier, sometimes PLCCs from different suppliers have different solderability protectant materials on the component leads and reaction of these different materials with the solder can create different visual effects. | | Good luck | | Dave F | Well the answer to your Questions. 1. yes, all the component is the same. Cause it is panelized. 2. Analysis was performed and either the pad got insufficient solder or did not flow due to (maybe) not enough heat. 3. The component is made in house with gold leads. 4. the failed are from various lot. 7. this is part of a new product. 8. My profile looks good with a good slope and soak time according to Amtech recommended profile.

The parts are but through a double reflow cause it has only one part on top and one plcc on the bottom that is palced on another assembly. it comes in a panel of 16 with a single panel being 1/2 x 1/2 in. and the panel 4.5 x 4.5 in with gold leads on both devices. I hope this info would be helpful. Thanks again.

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Michael N.

#11823

Re: Ceramic + Hi-temp solder | 22 April, 1999

Well Dave what are pads on the ceramic board is composed of is Paladium Silver but it is on the bottom, then comes the copper, then it is coated with tin, then it is coated again with nickel. What makes it even harder is that are devices are Gold leads. So what do I do? We are in the Process of getting the component sent out to remove the Gold content and see if it will solder on better. Any suggestions? The part is manufactured in house.THanks again.

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#11824

Re: Ceramic + Hi-temp solder | 22 April, 1999

Michael: Two things:

1. Profile:

A. Your FR4 profile will not produce good solder connections on your ceramic substrate. Hey wait a minute, you soldered FR4 at 250C??

Ceramic is a themal sponge. You'll need to play, but it should be easy compared to FR4. The ceramic distributes the heat more evenly. Your zone settings can probably stay pretty much the same, but you may need to SLOOOWWWW things down to provide time to stabilize the temp across the board. A good rule of thumb is to keet rise and fall times to 1.5 deg. C/second or less and you should be okay. B. Get your paste suppliers help C. You still haven't told me how you KNOW your profile is accurate

2. Solder preservative

A. Pad coating. You will never get a good solder connection when solding to Ni. I'd rather solder to dirt than Ni. B. Component lead coating. What kind of Au plating is on the componet leads? C. Solder connection. Mixing Au, Ag, Sn(??), and what ever you have on your pads sounds like an odd alloy. Will it stand-up to the environment where you need a ceramic board?

Good luck

Dave F

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