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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Re: sm ic's

Jason

#10441

sm ic's | 24 July, 1999

We are going to smt ic's on the component side of our pcb's. The problem is we are going to have to do this by hand. We have a hot air station and vac pencil, but How reliable is this process. We've tried it on proto's and had some shorting problems. And in some cases we feel the heat destroyed the ic They are soic-8. we are also considering an air bath system. Any suggestions would be appreciated

THANKS IN ADVANCE JASON

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ScottM

#10442

Re: sm ic's | 24 July, 1999

| We are going to smt ic's on the component side of our pcb's. | The problem is we are going to have to do this by hand. | We have a hot air station and vac pencil, but How reliable is this process. | We've tried it on proto's and had some shorting problems. | And in some cases we feel the heat destroyed the ic | They are soic-8. | we are also considering an air bath system. | Any suggestions would be appreciated | | | THANKS IN ADVANCE JASON | Why by hand, you don't have an oven? If you don't have too many, try soldering by hand - the PACE miniwave works wonders. By the time you fiddled with the hot air, et. al. a good solderer would have twice as many installed. SO-8s are pretty simple, use a stnadard soldering iron (if you don't have a PACE), not hot air. Look at the time to do each job and pick the quickest.

Scott

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#10443

Re: sm ic's | 26 July, 1999

| | We are going to smt ic's on the component side of our pcb's. | | The problem is we are going to have to do this by hand. | | We have a hot air station and vac pencil, but How reliable is this process. | | We've tried it on proto's and had some shorting problems. | | And in some cases we feel the heat destroyed the ic | | They are soic-8. | | we are also considering an air bath system. | | Any suggestions would be appreciated | | | | | | THANKS IN ADVANCE JASON | | | Why by hand, you don't have an oven? If you don't have too many, try soldering by hand - the PACE miniwave works wonders. By the time you fiddled with the hot air, et. al. a good solderer would have twice as many installed. SO-8s are pretty simple, use a stnadard soldering iron (if you don't have a PACE), not hot air. Look at the time to do each job and pick the quickest. | | Scott | The problem sounds like you don�t have an oven and you are just starting with SMD. Normally when you start a new technology there is not much help as for books and some salespeople whose main goal is to sell equipment. What you really need and how you do the work best and most efficient you have to figure out by yourself by a) getting independent advice from proficient people b) start small, means don�t start with the complicated stuff c) give it time d) spend money for equipment only if you are convinced it�s necessary and fits your desire (actually the hardest piont of all in my opinion) e) choose your smartest guy for the task f) get people trained in SMD-rework, that starts with handsoldering techniques even for finepitch g) stay tuned to the scene h) keep things as simple as possible i) first investment should be made in a very good optical equipment that you are able to do handsoldering underneath, it makes your people more sensitive for the soldering

Don�t blow hot air onto your boards unless it�s necessary, hot air needs delicate processcontroll or somebody with the right feeling (that�s how it�s done in many places) for it. People who know what they�re doing and have sufficient knowledge of the final results will do things better and (hopefully) more efficient.

Wolfgang

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Justin Medernach

#10444

Re: sm ic's | 29 July, 1999

| We are going to smt ic's on the component side of our pcb's. | The problem is we are going to have to do this by hand. | We have a hot air station and vac pencil, but How reliable is this process. | We've tried it on proto's and had some shorting problems. | And in some cases we feel the heat destroyed the ic | They are soic-8. | we are also considering an air bath system. | Any suggestions would be appreciated | | | THANKS IN ADVANCE JASON | Wolfgang hit it right on the nose. If you have a reflow oven, run a double sided reflow process. The components on the bottom side during reflow will adhere to the board via the surface tension of the molten solder. If you don't have an oven, than irons are the way to go. Sounds like golf advice. The hot air pens are simply blowtorches and in the hands of ametures, they can cause significant damage. Irons will probably be faster as well.

Regards, Justin

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DL

#10445

Re: sm ic's | 29 July, 1999

| | We are going to smt ic's on the component side of our pcb's. | | The problem is we are going to have to do this by hand. | | We have a hot air station and vac pencil, but How reliable is this process. | | We've tried it on proto's and had some shorting problems. | | And in some cases we feel the heat destroyed the ic | | They are soic-8. | | we are also considering an air bath system. | | Any suggestions would be appreciated | | | | | | THANKS IN ADVANCE JASON | | | Wolfgang hit it right on the nose. If you have a reflow oven, run a double sided reflow process. The components on the bottom side during reflow will adhere to the board via the surface tension of the molten solder. If you don't have an oven, than irons are the way to go. Sounds like golf advice. The hot air pens are simply blowtorches and in the hands of ametures, they can cause significant damage. Irons will probably be faster as well. | | Regards, | Justin |

SMT SOIC 8,

Are a breeze in the hands of good Hot Air Pencil Operators, However, if you must do this by hand and have no experienced rework persons invest in a HOT AIR REWORK station simulates the reflow oven process much better. Less expensive and will help you out with bigger SMT parts as well, instead of scrapping them. You can forget reworking anything with over 8 legs with a Hot Air Pencil, just not practical and you'll have cold joints if the person is less experienced.

Dave Kearns

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