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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Re: PTH connectors mounted on SMD process

Pascal G

#8077

PTH connectors mounted on SMD process | 21 December, 1999

Hello guys ,

we just started first trials on PTH connectors mounted in SMD. Our first results show big deviation of solder filing in the hole and also a dramatic decreasing of mounting spped on pick & place equipement.

1 - Did someone uses proflow system to be sure to have a correct % of solder in the hole? 2 - Do you think robot (JOT , PMJ,...) can be preferd for mounting process ?

Regards Pascal

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Brian W.

#8078

Re: PTH connectors mounted on SMD process | 21 December, 1999

When doing PIH processes, it is critical that you control the solder VOLUME, not the height. You must define the process, monitor it and control chart it to keep the paste volume consistent. You have do some careful engineering to determine how much solder volume you need, and what shape the apertures should be. Another factor is how long your leads are throught the board. If they are too long, suggested is no more than 1.5mm (.060 inch), the solder will not draw back to the joint, but will stay out along the lead. There are some excellent reference materials out there. Bob Willis in the UK comes to mind. You should also keep in mind that the solder joints may not look like perfect IPC through hole joints. If I had my druthers, I would use the placement equipment. It will be more accurate and less prone to deviation than hand placing. More of the placement parameters can be controlled than hand placment, which should keep more of the defects down (such as smearing paste under the connectors, leading to bridging). When done correctly, it can be a very good process, but you must take the time to engineer it and control it correctly.

IMHO, Brian W.

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Eyal Epstein

#8079

Re: PTH connectors mounted on SMD process | 27 December, 1999

We at Celtronix have extensive experience and customers, whom we have supplied Pin in Paste solutions. We can send you a lot of information, including references to our customers. Celtronix is a supplier of odd form automation solutions, including machines, feeding, process design and implementation. please contact me directly via email or call Int'l +972-3- 6485396 Best regards, Eyal Epstein

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Dan Woodward

#8080

Re: PTH connectors mounted on SMD process | 28 December, 1999

Certainly automatic placement, preferably with vision system assistance will yield a more repeatable process. Process repeatability (paste deposition, connector placement, reflow cycle, etc.) will be your key to success here.

Another possibility you might want to consider is using pressfit connectors instead. The pressfit connection is very reliable, and the assembly process is simple. Surprisingly, the electro-mechanical performance of the pressfit connection is actually better than solder!

If the tails of the pins are long, or you are installing connectors on the 2nd side of an SMT board, pressfit may be your only choice. All of the major connector manufacturers provide a variety of pressfit connectors.

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Vahid Vatannia

#8081

Re: PTH connectors mounted on SMD process | 28 December, 1999

Dan, Is there an article or a paper that compare solder joints strenght verses pressfit? Thnak you.

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Dan Woodward

#8082

Re: PTH connectors mounted on SMD process | 29 December, 1999

I am not sure if I have seen an article comparing solder joint strength Vs pressfit although I am sure this has been researched by literally hundreds of companies before they felt comfortable going to pressfit. I know one of the issues with solder is cracking under vibration, or due to defective soldering. Properly applied pressfit pins maintain a gastight connection with the PCB and don't have any cracking tendency.

I will do a little more research and let you know what I find. In the mean time, there is some very good history in pressfit connector usage.

My personal experience with pressfit pins goes back to the mid-80's when I worked for Northern Telecom. We were using pressfit pins in telecom applications (backplanes for switching systems) by the many millions per year. As you probably know, the telecommunications industry has always maintained very high reliability standards because the phone system is considered an essential service for safety. At the same time AT&T was using an even larger number of pressfit pins in their competing digital switches.

In the more recent past I have stayed in touch with the major connector manufacturers such as AMP, BERG, Teradyne, Erni, EPT etc.. Together they ship tens of millions of pressfit connectors each year.

You may be familiar with the relatively new industrial PCI bus called Compact PCI. It uses all pressfit connectors. Intel is using pressfit connectors on their high end servers, and most new high end datacom/telecom applications use pressfit connectors.

As you can tell, I am a big proponent of this technology and I think it will grow at a fast pace for years. I will let you know if I find any interesting reports. Meanwhile, feel free to contact me if you would like to discuss this further.

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Dave

#8083

Re: PTH connectors mounted on SMD process | 29 December, 1999

Does anyone have information on any automatic machines that place pressfit connectors (manufacturers, cost, websites, etc.)?

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Dan Woodward

#8084

Re: PTH connectors mounted on SMD process | 30 December, 1999

Hi Dave,

ASG in Florida (www.goasg.com) manufactures machines specifically to pick and place pressfit connectors, including vision inspection of the pins. They also manufacture a line of electric servo presses for pressfit connectors. I would be happy to discuss this further offline.

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#8085

Re: PTH connectors mounted on SMD process | 30 December, 1999

Dave: Dan's correct. ASG is good. Consider Motion Automated also. good luck. Dave F

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Vahid Vatannia

#8086

Re: PTH connectors mounted on SMD process | 5 January, 2000

Thanks for the info. I am going to call AMP and ASG. Thanks again.

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