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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Chris Newell

#13746

In-line lead trimmers | 21 October, 1998

I have been requested to explore the possibilities of using an inline lead trimmer in our manufacturing process. I have a few questions I need answered. 1. Can anyone recommend a good model of trimmer for in-line use? 2. We do double sided SMT, mixed technology boards. I am worried about parts being shaved off during the trimming process. Will this be a problem? 3. I always thought that a secondary reflow was required after trimming to insure there are no fractured solder joints. Is this true or is there a way around this problem?

Any help would be greatly appreciated.

Sincerely, Chris Newell SMT Supervisor Epson Portland Inc.

reply »

Dave f

#13747

Re: In-line lead trimmers | 23 October, 1998

| I have been requested to explore the possibilities of using an inline lead trimmer in our manufacturing process. I have a few questions I need answered. | 1. Can anyone recommend a good model of trimmer for in-line use? | 2. We do double sided SMT, mixed technology boards. I am worried about parts being shaved off during the trimming process. Will this be a problem? | 3. I always thought that a secondary reflow was required after trimming to insure there are no fractured solder joints. Is this true or is there a way around this problem? | | Any help would be greatly appreciated. | | Sincerely, | Chris Newell | SMT Supervisor | Epson Portland Inc. | | I have been requested to explore the possibilities of using an inline lead trimmer in our manufacturing process. I have a few questions I need answered. | 1. Can anyone recommend a good model of trimmer for in-line use? | 2. We do double sided SMT, mixed technology boards. I am worried about parts being shaved off during the trimming process. Will this be a problem? | 3. I always thought that a secondary reflow was required after trimming to insure there are no fractured solder joints. Is this true or is there a way around this problem? | | Any help would be greatly appreciated. | | Sincerely, | Chris Newell | SMT Supervisor | Epson Portland Inc. |

Chris:

1 I know of no in-line lead trimmers. I will not let that stop me. Well at least I am familiar with off-line trimmers. My following comments are from that perspective. 2 If you plan to shear PTH leads after reflowing your second side SMT parts, 2A You assuredly will be reworking some SMT parts. 2B Your product spec will have to allow you to have finished lead lengths of a couple millimeters (the height of a typical chip part), maybe longer, depending on the second side component height. 2C Trimming will not leave some leads standing upright. Trimming bends leads at all kinds of cuckoo angles. Leads may be even touching other leads given the lead length in 2B above. 2D You will have to clean-up a mess. Trimming is nasty from two perspectives. (1) Cut leads will be flying all over the place in your trimming box. (2) There will trimming residue all over the surface of the board, under leads and components, and inside the box. I�ll bet the cutting residues are a hazardous material. 2E Trimming can be noisy 3 Your comment is difficult to argue with.

Can we take a step backward? Since you�re trimming leads, you must be hand placing the PTH parts, trimming leads by hand, and then reflowing them. And you�re trying to reduce your lead trimming costs. Consider some alternatives:

1 Buy a refurbished Contact 400, guided assembly machine. They cost $15k. Chad and Ragan (sp?) make similar machines. A word of caution here, make sure you understand the cut and clinch capabilities of the machine relative to your second side SMT components. It could be embarrassing, because many of the used machines out-there were "well broken in" before people could spell SMT. 2 Buy some used lead forming and trimming machines, so you can "snap-in" your PTH parts that are trimmed to the proper length. And then wave solder as usual. GPD, Hepco, Manix, and APS make wonderful machines and die. 3 Buy used automated PTH insertion machines. Universal and Amistar have been making these machines for years and there are bargains out there.

TTYL

Dave F

reply »

Dave

#13748

I agree Dave. | 27 October, 1998

I completely agree with what Dave said previously about the trimming process. I spent the first 6 months at my current job removing this process from our assembly floor. We had several problems with the process including: 1) "flags" from the leads not shearing off totally and causing shorts. 2) Blades cutting into the actual PCB when there was warpage or operator error. 3) Fractured joints due to a dull cutting blade. 4) Increased time spent per PCA due to this extra process step. 5) Increased inspection time needed correcting the defects from this process. 6) Extra noise on the floor that we don't need.

Try to work on getting the leads trimmed before the wave solder process to avoid having to use this process. Its a very archaic method which should not be used on any production floor. Avoid it at all costs!

Sorry for the bad rapp to all the trimming machine salemen out there but this process really stinks.

Dave

reply »

Michel SORGIUS

#13749

Re: In-line lead trimmers | 16 November, 1998

We have board handlers for automatization of lead trimmers.

Michel

| I have been requested to explore the possibilities of using an inline lead trimmer in our manufacturing process. I have a few questions I need answered. | 1. Can anyone recommend a good model of trimmer for in-line use? | 2. We do double sided SMT, mixed technology boards. I am worried about parts being shaved off during the trimming process. Will this be a problem? | 3. I always thought that a secondary reflow was required after trimming to insure there are no fractured solder joints. Is this true or is there a way around this problem? | | Any help would be greatly appreciated. | | Sincerely, | Chris Newell | SMT Supervisor | Epson Portland Inc. |

reply »

PCB X-Ray Inspection System

SMT Custom Nozzles