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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Re: Problems with wave solder

Charles Stringer

#13471

Problems with wave solder | 17 November, 1998

For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please

reply »

Chrys

#13472

Re: Problems with wave solder | 17 November, 1998

| For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | Hmmm,

If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere.

If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it.

Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can...

reply »

Earl Moon

#13473

Re: Problems with wave solder | 17 November, 1998

| | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | Hmmm, | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed.

Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it).

If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look.

Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing.

On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming.

What else could it be. Let me count them all in a life time.

Hope the measurements provide evidence of cause,

Earl Moon

reply »

Dave F

#13474

Re: Problems with wave solder | 18 November, 1998

| | | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | | | Hmmm, | | | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | | | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed. | | Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it). | | If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look. | | Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing. | | On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming. | | What else could it be. Let me count them all in a life time. | | Hope the measurements provide evidence of cause, | | Earl Moon | Hey Earl, What zis "hang quality conformance test circuitry on your MLB panels" stuff?

1 How do I do it? 2 What does it look like? 3 How do I use it?

Dave F

reply »

Kelly

#13475

Re: Problems with wave solder | 19 November, 1998

| For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please |

Have you checked your upline process? You said nothing has changed in your wave process, but what about your reflow. Has anything changed there that could cause warpage?

reply »

Earl Moon

#13476

Re: Problems with wave solder | 19 November, 1998

| | | | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | | | | | Hmmm, | | | | | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | | | | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | | | | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | | | | | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed. | | | | Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it). | | | | If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look. | | | | Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing. | | | | On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming. | | | | What else could it be. Let me count them all in a life time. | | | | Hope the measurements provide evidence of cause, | | | | Earl Moon | | | Hey Earl, What zis "hang quality conformance test circuitry on your MLB panels" stuff? | | 1 How do I do it? | 2 What does it look like? | 3 How do I use it? | | Dave F | Ah Dave, I'm certainly glad you asked the question. I was sure that if anyone did (doubtful), it would be you.

Look at IPC-D-275, or whatever it has become (2222 or 2221 or?) and you will see all manner of sample quality conformance test circuitry. This circuitry is made up of individual test coupons that are electrically or destructively tested (saving the board and providing consistent data lot to lot, etc.). You will see exactly which coupon is used for what testing (you can add your own custom type if you wish) and where the test circuitry must be placed on each panel.

Test circuitry represents all the features of each board on each panel. This means it is made up of holes, pads, traces, and spaces exactly representative of the boards on the panel. Two circuits are required on each panel as indicated in the standard.

All possible quality and reliability testing may be done. Tests include x-sectional analysis as received and after thermal stress to determine hole wall and laminate quality. Impedance and continuity testing is done using other coupons on the circuitry. SIR, dielectric withstanding voltage, solder mask adhesion and cure, cleanliness, solderability, conductor bond strength, and other requirements become consistently testable. This provides a firm foundation for supplier process improvement and internal SPC.

Go get 'em Dave and thanks for all your invaluable input over time,

Earl Moon

reply »

Dave F

#13477

Re: Problems with wave solder | 19 November, 1998

| | | | | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | | | | | | | Hmmm, | | | | | | | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | | | | | | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | | | | | | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | | | | | | | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed. | | | | | | Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it). | | | | | | If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look. | | | | | | Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing. | | | | | | On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming. | | | | | | What else could it be. Let me count them all in a life time. | | | | | | Hope the measurements provide evidence of cause, | | | | | | Earl Moon | | | | | Hey Earl, What zis "hang quality conformance test circuitry on your MLB panels" stuff? | | | | 1 How do I do it? | | 2 What does it look like? | | 3 How do I use it? | | | | Dave F | | | Ah Dave, I'm certainly glad you asked the question. I was sure that if anyone did (doubtful), it would be you. | | Look at IPC-D-275, or whatever it has become (2222 or 2221 or?) and you will see all manner of sample quality conformance test circuitry. This circuitry is made up of individual test coupons that are electrically or destructively tested (saving the board and providing consistent data lot to lot, etc.). You will see exactly which coupon is used for what testing (you can add your own custom type if you wish) and where the test circuitry must be placed on each panel. | | Test circuitry represents all the features of each board on each panel. This means it is made up of holes, pads, traces, and spaces exactly representative of the boards on the panel. Two circuits are required on each panel as indicated in the standard. | | All possible quality and reliability testing may be done. Tests include x-sectional analysis as received and after thermal stress to determine hole wall and laminate quality. Impedance and continuity testing is done using other coupons on the circuitry. SIR, dielectric withstanding voltage, solder mask adhesion and cure, cleanliness, solderability, conductor bond strength, and other requirements become consistently testable. This provides a firm foundation for supplier process improvement and internal SPC. | | Go get 'em Dave and thanks for all your invaluable input over time, | | Earl Moon | Earl: I'm a memeber of the "spurious remark police." I've been "tasked" with monitoring your posts to assure that your spurious references are high-lighted and that you account for them.

Thanks to you Earl.

TTYL

Dave F

reply »

Earl Moon

#13478

Re: Problems with wave solder | 19 November, 1998

| | | | | | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | | | | | | | | | Hmmm, | | | | | | | | | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | | | | | | | | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | | | | | | | | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | | | | | | | | | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed. | | | | | | | | Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it). | | | | | | | | If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look. | | | | | | | | Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing. | | | | | | | | On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming. | | | | | | | | What else could it be. Let me count them all in a life time. | | | | | | | | Hope the measurements provide evidence of cause, | | | | | | | | Earl Moon | | | | | | | Hey Earl, What zis "hang quality conformance test circuitry on your MLB panels" stuff? | | | | | | 1 How do I do it? | | | 2 What does it look like? | | | 3 How do I use it? | | | | | | Dave F | | | | | Ah Dave, I'm certainly glad you asked the question. I was sure that if anyone did (doubtful), it would be you. | | | | Look at IPC-D-275, or whatever it has become (2222 or 2221 or?) and you will see all manner of sample quality conformance test circuitry. This circuitry is made up of individual test coupons that are electrically or destructively tested (saving the board and providing consistent data lot to lot, etc.). You will see exactly which coupon is used for what testing (you can add your own custom type if you wish) and where the test circuitry must be placed on each panel. | | | | Test circuitry represents all the features of each board on each panel. This means it is made up of holes, pads, traces, and spaces exactly representative of the boards on the panel. Two circuits are required on each panel as indicated in the standard. | | | | All possible quality and reliability testing may be done. Tests include x-sectional analysis as received and after thermal stress to determine hole wall and laminate quality. Impedance and continuity testing is done using other coupons on the circuitry. SIR, dielectric withstanding voltage, solder mask adhesion and cure, cleanliness, solderability, conductor bond strength, and other requirements become consistently testable. This provides a firm foundation for supplier process improvement and internal SPC. | | | | Go get 'em Dave and thanks for all your invaluable input over time, | | | | Earl Moon | | | Earl: I'm a memeber of the "spurious remark police." I've been "tasked" with monitoring your posts to assure that your spurious references are high-lighted and that you account for them. | | Thanks to you Earl. | | TTYL | | Dave F | Dave,

I've always respected the police without understanding all they are empowered to do. In your case, I feel comfortable you will not exceed your authority by becoming individually responsible as taking upon yourself the task of punishment.

That notwithstanding, I left out some pertinent information for you all concerning plating thickness, dielectric thickness compared with TDR readings, etc.. How irresponsible! I should be locked up (in a women's prison of course), but only for a short time as I'm getting to old to - what was the question?

My question to you is: Where do you find all your information? I don't expect an answer or expect you to reveal secrects.

Enjoy,

Earl Moon

reply »

Dave F

#13479

Re: Problems with wave solder | 19 November, 1998

| | | | | | | For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please | | | | | | | | | | | | | Hmmm, | | | | | | | | | | | | If nothing changed in your process and nothing changed in the board vendor's process, there wouldn't be a problem, right? So something has changed somewhere. | | | | | | | | | | | | If you have verified your process with a datalogger, then I would suspect the vendor. This happened to me once, and I was lucky enough to work with a guy who came from a board shop. Turned out they used the wrong B-stage in the lamination, and the other process engineer picked up on it. | | | | | | | | | | | | Since I'm not a board fab guru, I can't tell you how to investigate this, but I bet Earl can... | | | | | | | | | | | Thank you for that warm introduction. Something funny happened on the way to work today. I was hit with a flying, but sagging, multilayer PCB. I was unharmed, but the board lie gasping its last breath. Upon investigation, I found that if no other problems existed, this poor specimen displayed exactly the same symptoms Chrys discussed. | | | | | | | | | | Sagging boards that never sagged before. Not a new story, but always interesting. Yes, the answer could be found in the multilayer construction or board shop lamination process management (or loss of it). | | | | | | | | | | If you are sure your processes remain in control and capable of providing product quality meeting specified requirements, where else to look. The only problem is how do you look. | | | | | | | | | | Ah yes, x-section a board and compare its construction to requirements clearly indicated on your master drawing. This means determining material selections and specified layup requirements. Of course, you should use a micrometer to measure specified thickness first - just in case some prepreg or core material is wrong or missing. | | | | | | | | | | On it goes, but the best way to ensure this type thing never happens is to hang quality conformance test circuitry on your MLB panels and ensure the board shop x-sections to ensure specified constructions. If it is as discussed, this problem is easily fixed, and more easily prevented before you accept 10,000 boards at incoming. | | | | | | | | | | What else could it be. Let me count them all in a life time. | | | | | | | | | | Hope the measurements provide evidence of cause, | | | | | | | | | | Earl Moon | | | | | | | | | Hey Earl, What zis "hang quality conformance test circuitry on your MLB panels" stuff? | | | | | | | | 1 How do I do it? | | | | 2 What does it look like? | | | | 3 How do I use it? | | | | | | | | Dave F | | | | | | | Ah Dave, I'm certainly glad you asked the question. I was sure that if anyone did (doubtful), it would be you. | | | | | | Look at IPC-D-275, or whatever it has become (2222 or 2221 or?) and you will see all manner of sample quality conformance test circuitry. This circuitry is made up of individual test coupons that are electrically or destructively tested (saving the board and providing consistent data lot to lot, etc.). You will see exactly which coupon is used for what testing (you can add your own custom type if you wish) and where the test circuitry must be placed on each panel. | | | | | | Test circuitry represents all the features of each board on each panel. This means it is made up of holes, pads, traces, and spaces exactly representative of the boards on the panel. Two circuits are required on each panel as indicated in the standard. | | | | | | All possible quality and reliability testing may be done. Tests include x-sectional analysis as received and after thermal stress to determine hole wall and laminate quality. Impedance and continuity testing is done using other coupons on the circuitry. SIR, dielectric withstanding voltage, solder mask adhesion and cure, cleanliness, solderability, conductor bond strength, and other requirements become consistently testable. This provides a firm foundation for supplier process improvement and internal SPC. | | | | | | Go get 'em Dave and thanks for all your invaluable input over time, | | | | | | Earl Moon | | | | | Earl: I'm a memeber of the "spurious remark police." I've been "tasked" with monitoring your posts to assure that your spurious references are high-lighted and that you account for them. | | | | Thanks to you Earl. | | | | TTYL | | | | Dave F | | | Dave, | | I've always respected the police without understanding all they are empowered to do. In your case, I feel comfortable you will not exceed your authority by becoming individually responsible as taking upon yourself the task of punishment. | | That notwithstanding, I left out some pertinent information for you all concerning plating thickness, dielectric thickness compared with TDR readings, etc.. How irresponsible! I should be locked up (in a women's prison of course), but only for a short time as I'm getting to old to - what was the question? | | My question to you is: Where do you find all your information? I don't expect an answer or expect you to reveal secrects. | | Enjoy, | | Earl Moon | Earl: We police are not tasked with punishment. Punishment is meaded-out by a higher authority. Often that's working with (or worse, working for) someone of a lower genealogical order.

I asked "How do I use it?," but you didn't tell. I figured you wrote something on in in "PC Fab" and would check there. As a minimum, I figured I could do another posting, say in a week or two, and pose the question again and maybe get another snippet for some sage (or is it basil).

Where do I find my information? I collect it. The difficult part is finding where I put it.

Dave

reply »

Brian Conner

#13480

Re: Problems with wave solder | 19 November, 1998

| For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please

Has any preventive maintance been done on your wave lately? If it computer programmed, the tolerance on the conveyor width may be too tight causing the board to warp - unfortunately, it usually will warp INTO the solder. If the conveyor width is manually controlled, there are several cariables that you need to look at.

If you use pallets, you might have a tolerance stack-up issue?

reply »

Mike Demos

#13481

Re: Problems with wave solder | 23 November, 1998

Charles:

Here are a few possibilities you might want to check:

1) Conveyor width -- if the conveyor is too tight this will cause the boards to buckle as they go through the preheat section. We recently had this happen when we changed operators.

2) Conveyor parallelism -- try taking a board and manually pushing it all the way through the wave solder machine. It is possible that the conveyor is not uniform throughout the machine.

3) Rail wear -- Bent fingers or running the conveyor too tight on pallets can cause the extruded rails to wear. In a previous job I had to replace the rails on a machine. If we had been doing adequate PM at the time, we would have noticed the metal shavings in the finger cleaner.

Good luck!

Mike.

| For some as yet unkown reason, we have started to have some boards sag and go under the wave. The boards are surface mount top side and conventional components wave soldered. We have checked the wave hight and both the profiles on the wave solder and SM infra red reflow. Wave preheat is 95C, Reflow is 150C plateau, 230C peak with 60s above 183C (Solder liquidus). These are not new boards and whilst they have a lot of cut outs we have been processing them for many years with very few problems. Needless to say our PCB supplier says nothing has changed his end. Any suggestions please |

reply »

reflow oven profiler