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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Post reflow solder joint inspection

#27028

Post reflow solder joint inspection | 28 January, 2004

Has anyone in the industry had even a fair amount of success inspecting reflowed solder joints to IPC class 3 standards? I am not interested in hearing from system reps or people who work for an AOI manufacturer.

Thanks,

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#27088

Post reflow solder joint inspection | 2 February, 2004

90% of the assemblies our company produces are class 3 and we have no problem at all inspecting or getting class 3 quality through reflow. Rarely do we have touch up because of insufficient or poorly reflowed solder joints. What are the problems you are having?

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swagner

#27105

Post reflow solder joint inspection | 2 February, 2004

We are not having a problem, we have a customer that would like us to use post reflow AOI to inspect the solder joints to class three. I would like to see if anyone is having sucess doing this.

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Dean

#27107

Post reflow solder joint inspection | 2 February, 2004

I find this disturbing when customers dictate your process and equipment? Your responsibility is to deliver a quality product on time. Why would your customer care HOW you achieve this? Hence the success of Chinese manufacturing.

I have one customer who initially dictated a lead free process requirement and then went so far as to identify the equipment (printer P&P furnace etc...) I laughed outloud as the equipment they specified was OLDER and LESS capable than the equipment I already had!

Today I had a customer profess to me how much of an expert he was in the industry (during a problem solving conference call). He insisted we had unreflowed solder on 1 pilot board. He detemined this from 2 emailed digital photos (that I took). Then he went on to suggest I swithch from a no clean over to a low solids RMA flux type. Can someone eplain to me how a low solids flux type will solve (an aleged) unreflowed solder problem? There was no unreflowed solder and he was no expert.

Good luck

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#27110

Post reflow solder joint inspection | 3 February, 2004

About 2 years ago our company tried to go with a post reflow AOI inspection. This AOI was suppose to be able to inspect to a level class 3 product. **It is impossible** You cannot inspect for a heel fillet and inspecting for poor wetting is a very fine line. Alot of it also depends on the component quality. We had some components that had degraded plating but was still acceptable, well this plating mixed with good solder paste would give dull solder joints, this in turn would call a false defect. This went on and on. We had a very bad experience. I am 100% for AOI if your inspecting placement, presence, or even component type if possible. But when it comes to solder joint quality expecially to class 3, sorry, theres nothing more reliable than the human eye. If your going to inspect to class 3 with AOI you need to make sure your going to have a very consistant parts supplier and not have your purchasing department buy bulk parts from different suppliers. What I ran into was that because of this I was having to reprogram part sizes, colors, as well as solder joint inspection changes if your parts are tinned more or less. Keep these things in mind if your going to go the AOI way. You will probably never eliminate reflow inspection to class 3 product expecially on complex assemblies. Also keep in mind that if your running BGA's that your will need something like AXI.

Just thought I would give my input..

Thanks, Paul

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swagner

#27113

Post reflow solder joint inspection | 3 February, 2004

Paul, do you have any kind of false failure data for the application you struggled with? Also what amount of manpower did you use to operate the system(s).

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#27114

Post reflow solder joint inspection | 3 February, 2004

We had the data at the time and it was quite high. More false calls then anything. I do not have the data anymore it since has been archived. When the system was introduced we had 1 engineer and 2 operators trained for programming and running the machine. Since the only way we had to program each assembly was online the operators did most of the programming. Before the assemblies were initially ran. Machine ran 18 hours a day, both 1st and 2nd shift. We had only one machine used to inspect 3 assembly lines so we only ran our most complex and high volume assemblies through the AOI. The problems we had were the inspection of poor wetting. At one point we had technicians come from the AOI manufacturer insisting that they could get the machine to inspect poorly wetted solder joints and they were unsuccessful. Unfortuniently because IPC is so vague on poorly wetted solder joints they said the solder joint was ok and our quality director disagreed. Because of this we still inspect surface mount.

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