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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


MPM AP25, separation problems

Views: 2242

Hello! I suspect that our MPM AP25 has separation problem... - Oct 28, 2005 by Pavel Murtishev  

#37393

MPM AP25, separation problems | 28 October, 2005

Hello!

I suspect that our MPM AP25 has separation problems (poor stencil � PCB separation). I observe a lot of �dog ears� after print stroke. And this is 100% machine problem, I�m sure. What machine parts should I check first time to avoid separation problems? Tactile sensor, tooling or somewhat else? Thank you.

BR, Pavel

reply »


Rob

#37394

MPM AP25, separation problems | 28 October, 2005

From what I remember there is a "snap off" setting in the AP25, where you can set the separation speed & I think it may also vibrate the board a little.

reply »

#37397

MPM AP25, separation problems | 28 October, 2005

Once again, it isn�t the process problem. It�s machine problem. I�ve tried to change all of the parameters: printing speed, printing pressure, snap-off speed, snap-off distance, etc. No any effect. Defect still exists with different process parameters. So, it�s machine related problem.

BR, Pavel

reply »


RDR

#37398

MPM AP25, separation problems | 28 October, 2005

havfe you tried all paste manufacturers? Dog ears are usually from a little sticking to the aperture walls. this is usually the result of stencil design and or table seperation speed.

reply »

#37402

MPM AP25, separation problems | 28 October, 2005

Hello Since we have a few years experience with these printers we might be able to help. Is these problems always with the same components? Is this a new type of paste for you? Is there tape on the bottom of the stencil? And how much pressure do you have for down force on the squeege blades? Are you running "0" for a snap off? How often are you cleaning the bottom of the stencil? Is this problem on every board that goes across this machine? Keep in mind if it is a machine problem --it must happen all of the time then. This machine is smart enough to screw up just when it wants to. Hope we have given you some help. Regards and good luck Harry

reply »


URL

#37418

MPM AP25, separation problems | 28 October, 2005

Try turning off the vacuum. Could be related.

reply »

#37445

MPM AP25, separation problems | 31 October, 2005

Good day,

We are using dedicated vacuum tooling. I can�t turn off the vacuum because board will not be fixed at all.

BR, Pavel

reply »

#37446

MPM AP25, separation problems | 31 October, 2005

Good day,

I simply switched the production from MPM to other printing machine. Defect disappeared. Process parameters and process materials were the same. Stencil was the same. �Dog hides� somewhere in the machine.

BR, Pavel

reply »

#37447

MPM AP25, separation problems | 31 October, 2005

Good day,

Problem appears only with 0.5mm pitch components. Print quality for these components is unacceptable. Paste type isn�t new for us. No any tape on the bottom of the stencil. We apply enough pressure on squeegees, stencil remains clear after print stroke. Snap off is equal to zero. Stencil cleaner that is installed in our MPM is inefficient at all. No any positive effect after stencil cleaning. Yes, problem is on every board, going through the machine.

BR, Pavel

reply »

#37473

MPM AP25, separation problems | 31 October, 2005

Hello Did you just buy this machine on the used market? There is a possibility that the stencil is not height on all 4 corners ( from the center nest assembly. I don't under stand " the under stencil wiper is not working correctly". This is about the only assembly on the MPM's that almost never fails to work properly. Are you trying to use the wet wipe? If so this can cause the problem that you have. I would try this, turn the stencil and board 180 degrees, then reteach the board. This will tell you if the machine has a problem with the board and stencil not mating correctly.

reply »

#37474

MPM AP25, separation problems | 31 October, 2005

Hello again Just thought of another problem. Do you have board supports under the component that you are having problems with? harry

reply »

#37533

MPM AP25, separation problems | 2 November, 2005

Hello,

Thank you for answer.

We are using second hand machine. What do you mean saying that �stencil is not height on all 4 corners�? Does it have some inclination between corners? I mean that three corners of stencil are matching with PCB fine and one has some distance between PCB and stencil? Yes, we tried to use wet wipe, but solvent distributes non-uniformly along paper surface, hence wiper is inefficient at all and doesn�t wipes properly. Dry wipe gives no any effect at all especially on fine-pitch components. Stencil just remains dirty after wiping.

BR, Pavel

reply »

#37534

MPM AP25, separation problems | 2 November, 2005

We are using dedicated vacuum support. So we have support under all components.

reply »


URL

#37541

MPM AP25, separation problems | 2 November, 2005

So if you manually wipe the stencil your problem goes away?

reply »

#37542

MPM AP25, separation problems | 2 November, 2005

Hi!

It goes away only for one or two print strokes. After them the problem arises again. After first print stroke I inspect a lot of �dog ears� and a lot of paste not released from the stencil (it�s not a stencil design problem, other machine prints fine with the same stencil). After second I inspect unacceptable print at all. I�m afraid that manual stencil cleaning is very poor solution of the problem.

BR, Pavel

reply »


URL

#37543

MPM AP25, separation problems | 2 November, 2005

Yes, I agree, manual cleaning is not a solution, but does tell you you need to clean the stencil. You should have your stencil cleaner repaired and take that question mark away. Once all the question marks are goen you should be left with an answer.

What is wrong with the automatic cleaner anyway?

reply »

#37560

MPM AP25, separation problems | 2 November, 2005

Hello Sorry we have not answered sooner, been gone. There is a height adjustment on the wiper. You will find a round nob under it, that is a height adjustment. I expect the wiper is not going all of the way up. And you can also control the speed of the wiper ( set up , I would also try to wiper maybe 2 times instead of once, A lot of operators will wipe after 2-3 boards. This can get expensive ( paper is expensive), How much force are you putting on the squeege's? Is the down force at 0740, never change down force. Where are you located, as I'm going to be making a trip west soon. Harry

reply »

#37577

MPM AP25, separation problems | 3 November, 2005

Good morning,

Thank you for assistance. I�m not so experienced with MPM maintenance. Explain me please what is the difference between �squeegee down force� and �squeegee pressure�? Squeegee pressure is set so 5-6 Kg. How can I check squeegee down force? We are located at Russia, St. Petersburg (very beautiful �northern capital� of the Russia :)).

BR, Pavel

reply »

#37578

MPM AP25, separation problems | 3 November, 2005

Good morning,

Our automatic cleaner simply doesn�t clean. When I am inspecting clogged apertures I execute �cycle wiper� command few times. After wiping cycle apertures remain clogged. Zero effect. We tried to use solvent in production to improve cleaning, but solvent doesn�t wet the paper uniformly, hence wiping with solvent is inefficient also. Moreover, cleaner doesn�t have vacuum option.

BR, Pavel.

reply »

#37579

MPM AP25, separation problems | 3 November, 2005

"Harry Does Russia"......in a theater near you!

Seriously Pavel, Harry is real good on these machines. Why don't you two exchange e-mail addresses...take this off-line and I'm certain he will be able to fix this problem for you.

reply »

#37582

MPM AP25, separation problems | 3 November, 2005

Hello Well this is your lucky day, I would be glad to stop in russia on my way to california. And thanks rick I appreciate it. Would be glad to give him my e-mail, it is vmsales@alltel.net. Down force is very difficult to explain and MPM should not even put this one in the set up screens. He has some thing wrong that is probly not a machine problem. Thanks again rick. Harry

reply »

#37585

MPM AP25, separation problems | 3 November, 2005

Hi,

I�d just composed the e-mail to you. Thank you for assistance again. Please check your mail and let discuss the details.

BR, Pavel

reply »

PCB machines

Six Sigma Training