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8-layer board, about 1050 parts - V470.jpg
On Fri, 25 May 2007 17:10:16 -0700, John Larkin wrote:
On Fri, 25 May 2007 18:28:53 -0400, John Popelish Ooh! I want to try my hand at laying out one of those 16 strips. There were a bunch of ground loop and HV clearance issues, nastier than it looks. A few parts wound up on the bottom, just 4 caps per channel. One thing PADS doesn't do is replicate structures like this. I think it's part of an expensive options package that we don't have. Our guy does something tricky with Autocad to help him do this... lays out one channel then uses Autocad to make a 16x placement guide overlay or something. Oh, this is actually 6 layers! Mind if I ask which layer is which? There was a big thread on this not too long ago, it might be interesting to compare answers. :-) Thanks, Rich |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
1 Attachment(s)
On Tue, 29 May 2007 18:19:08 GMT, Rich Grise wrote:
On Fri, 25 May 2007 17:10:16 -0700, John Larkin wrote: On Fri, 25 May 2007 18:28:53 -0400, John Popelish Ooh! I want to try my hand at laying out one of those 16 strips. There were a bunch of ground loop and HV clearance issues, nastier than it looks. A few parts wound up on the bottom, just 4 caps per channel. One thing PADS doesn't do is replicate structures like this. I think it's part of an expensive options package that we don't have. Our guy does something tricky with Autocad to help him do this... lays out one channel then uses Autocad to make a 16x placement guide overlay or something. Oh, this is actually 6 layers! Mind if I ask which layer is which? There was a big thread on this not too long ago, it might be interesting to compare answers. :-) Thanks, Rich 1 top parts, pads, traces, silkscreen 2 traces 3 power pours, including isolated channel commons 4 mixed power pours and traces 5 ground 6 traces, a few bottom parts This is a little unusual in having ground on 5, but it had to do with the 16 isolated output channels. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Tue, 29 May 2007 20:13:05 -0700, John Larkin wrote:
On Tue, 29 May 2007 18:19:08 GMT, Rich Grise wrote: On Fri, 25 May 2007 17:10:16 -0700, John Larkin wrote: ... Oh, this is actually 6 layers! Mind if I ask which layer is which? There was a big thread on this not too long ago, it might be interesting to compare answers. :-) 1 top parts, pads, traces, silkscreen 2 traces 3 power pours, including isolated channel commons 4 mixed power pours and traces 5 ground 6 traces, a few bottom parts This is a little unusual in having ground on 5, but it had to do with the 16 isolated output channels. Thanks! Rich |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
tempus fugit wrote:
I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
1 Attachment(s)
On Fri, 1 Jun 2007 22:27:59 -0400, "tempus fugit"
wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No, it means that there are eight layers of etched copper foil. The board is a sandwich, thin (like 1 mil) copper layers separated by insulating layers (8 mils maybe) of epoxy-glass. The two outer copper layers, "top" and "bottom" are on the surface, so you can solder parts to them. Sometimes you need all those layers to distribute all the power supplies and make all the connections. Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. Parts are usually all on the top side of the board, but if things get really dense sometimes people put parts on the bottom, too. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Sat, 02 Jun 2007 02:56:25 GMT, "Michael A. Terrell"
wrote: tempus fugit wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? You've not heard of Mexican PCB's ?:-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
"John Larkin" wrote in
message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
Jim Thompson wrote:
On Sat, 02 Jun 2007 02:56:25 GMT, "Michael A. Terrell" wrote: tempus fugit wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? You've not heard of Mexican PCB's ?:-) Hell, I've seen them. Cincinnati Electronics made and assembled the boards for the modules used in the PRC-77 in Mexico. They had trouble with double sided, with plated through holes. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
On Sat, 2 Jun 2007 00:32:01 -0400, the renowned "Tom Del Rosso"
wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. You're not talking about blind vias are you? They're alive and well. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
"Spehro Pefhany" wrote in message
On Sat, 2 Jun 2007 00:32:01 -0400, the renowned "Tom Del Rosso" wrote: In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. You're not talking about blind vias are you? They're alive and well. Is that what it's called? It seems most boards don't use them. -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
On Sat, 2 Jun 2007 00:32:01 -0400, "Tom Del Rosso"
wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. I saw some boards that looked like that, but they were just plated vias without annular rings. I think there were cracking problems where the trace dived into the hole. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
2 Attachment(s)
On Sat, 02 Jun 2007 05:42:14 GMT, "Michael A. Terrell"
wrote: Jim Thompson wrote: On Sat, 02 Jun 2007 02:56:25 GMT, "Michael A. Terrell" wrote: tempus fugit wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? You've not heard of Mexican PCB's ?:-) Hell, I've seen them. Cincinnati Electronics made and assembled the boards for the modules used in the PRC-77 in Mexico. They had trouble with double sided, with plated through holes. Here's a bad via, on an 8-layer board, made in America! John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
John Larkin wrote:
On Sat, 02 Jun 2007 05:42:14 GMT, "Michael A. Terrell" wrote: Jim Thompson wrote: On Sat, 02 Jun 2007 02:56:25 GMT, "Michael A. Terrell" wrote: tempus fugit wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? You've not heard of Mexican PCB's ?:-) Hell, I've seen them. Cincinnati Electronics made and assembled the boards for the modules used in the PRC-77 in Mexico. They had trouble with double sided, with plated through holes. Here's a bad via, on an 8-layer board, made in America! John Was it just one bad via on one board, or a whole bad batch? Philco had a factory in Mexico that had lots of problems with consumer electronics, and Delco made a MAJOR design mistake when they used "Griplets" instead of plated through holes in a series of car radios. Another Philco screw up was using the wrong flux to solder enameled wire to terminals. It would eat right through the copper after a few years of use. You would pry open an IF transformer or remove the cover from a yoke and find a bunch of green dust where the wire used to be. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Sat, 02 Jun 2007 16:03:47 GMT, "Michael A. Terrell"
wrote: John Larkin wrote: On Sat, 02 Jun 2007 05:42:14 GMT, "Michael A. Terrell" wrote: Jim Thompson wrote: On Sat, 02 Jun 2007 02:56:25 GMT, "Michael A. Terrell" wrote: tempus fugit wrote: I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Thanks No. Haven't you ever heard of Vias and plated through holes? You've not heard of Mexican PCB's ?:-) Hell, I've seen them. Cincinnati Electronics made and assembled the boards for the modules used in the PRC-77 in Mexico. They had trouble with double sided, with plated through holes. Here's a bad via, on an 8-layer board, made in America! John Was it just one bad via on one board, or a whole bad batch? Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
John Larkin wrote:
Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. Were the via photos made before or after passing the boards through solder ovens? |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Sat, 02 Jun 2007 12:33:48 -0400, John Popelish
wrote: John Larkin wrote: Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. Were the via photos made before or after passing the boards through solder ovens? That was an as-received bare board. It could be that the boards - at least the ones they shipped us! - passed electrical bare-board testing but failed after reflow. At any rate, there was clearly a plating problem. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
"Spehro Pefhany" wrote in message
On Sat, 2 Jun 2007 00:32:01 -0400, the renowned "Tom Del Rosso" wrote: In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. You're not talking about blind vias are you? They're alive and well. Come to think of it, I know what blind vias are, but that's not it. These were from top and bottom layers, but it looked like the trace came to a dead end. -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Sat, 02 Jun 2007 09:51:01 -0700, the renowned John Larkin
wrote: On Sat, 02 Jun 2007 12:33:48 -0400, John Popelish wrote: John Larkin wrote: Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. Were the via photos made before or after passing the boards through solder ovens? That was an as-received bare board. It could be that the boards - at least the ones they shipped us! - passed electrical bare-board testing but failed after reflow. At any rate, there was clearly a plating problem. John Like maybe they had 25% fallouts at the flying probe test and ought to have had a gander at the PTHs... Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
On Sat, 02 Jun 2007 07:48:51 -0700, the renowned John Larkin
wrote: On Sat, 2 Jun 2007 00:32:01 -0400, "Tom Del Rosso" wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. I saw some boards that looked like that, but they were just plated vias without annular rings. I think there were cracking problems where the trace dived into the hole. John Ah, I've seen those maybe once... (ummm intentionally, that is). They can do cool stuff like blind 5 thou microvias but the cost might be too much for many applications. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
John Larkin wrote:
Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. They likely had fired some, or all of the more experienced employees to cut overhead. Someone in engineering sent a small sample order to qualify a new PCB vendor, and accidentally left out the film for a layer. Each layer was properly numbered, so it should have been obvious that the film for one of the center layers was missing. They went ahead and made the boards without even making a phone call or sending an e-mail. That layer carried the + & - 12 VDC supplies to 14 op amps, yet they claimed that it passed the 100% inspection. Gee, they had one chance to impress us, and did they. We found that the film was missing when they send the packet back, and the missing layer was found weeks later in the engineer's office where it had fallen off his cluttered desk, and behind a pile of file folders. They went right to the top of bad vendors. I was the one who found that the layer was missing, after they stuffed a single board, and almost every signal was O volts. The only part that worked was the couple CMOS chips that controlled the AGC board. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Sat, 02 Jun 2007 16:48:32 -0500, Spehro Pefhany
wrote: On Sat, 02 Jun 2007 09:51:01 -0700, the renowned John Larkin wrote: On Sat, 02 Jun 2007 12:33:48 -0400, John Popelish wrote: John Larkin wrote: Whole batch, maybe 5-20 bad vias per board. We canned that vendor. Strange, because they had been OK for years. But we paid them for 100% bare-board testing, and it was obvious that we didn't get it. Were the via photos made before or after passing the boards through solder ovens? That was an as-received bare board. It could be that the boards - at least the ones they shipped us! - passed electrical bare-board testing but failed after reflow. At any rate, there was clearly a plating problem. John Like maybe they had 25% fallouts at the flying probe test and ought to have had a gander at the PTHs... I think so. Somebody also said something about "operator judgement", which is a bizarre concept for a continuity test. It seems like most every PCB house goes to hell sooner or later. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
On Sat, 02 Jun 2007 16:53:34 -0500, Spehro Pefhany
wrote: On Sat, 02 Jun 2007 07:48:51 -0700, the renowned John Larkin wrote: On Sat, 2 Jun 2007 00:32:01 -0400, "Tom Del Rosso" wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. I saw some boards that looked like that, but they were just plated vias without annular rings. I think there were cracking problems where the trace dived into the hole. John Ah, I've seen those maybe once... (ummm intentionally, that is). They can do cool stuff like blind 5 thou microvias but the cost might be too much for many applications. Best regards, Spehro Pefhany What's standard these days? We're running 6 mil traces and 10 mil microvias, but "normal" keeps creeping down. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
On Sat, 02 Jun 2007 18:00:12 -0700, the renowned John Larkin
wrote: On Sat, 02 Jun 2007 16:53:34 -0500, Spehro Pefhany wrote: On Sat, 02 Jun 2007 07:48:51 -0700, the renowned John Larkin wrote: On Sat, 2 Jun 2007 00:32:01 -0400, "Tom Del Rosso" wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. I saw some boards that looked like that, but they were just plated vias without annular rings. I think there were cracking problems where the trace dived into the hole. John Ah, I've seen those maybe once... (ummm intentionally, that is). They can do cool stuff like blind 5 thou microvias but the cost might be too much for many applications. Best regards, Spehro Pefhany What's standard these days? We're running 6 mil traces and 10 mil microvias, but "normal" keeps creeping down. John A lot of them say 4mil/4mil (@.5oz) and something like 0.1mm for the vias (4 mils), but I have never needed to push it that far. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
"John Larkin" wrote in message ... On Sat, 02 Jun 2007 16:53:34 -0500, Spehro Pefhany wrote: On Sat, 02 Jun 2007 07:48:51 -0700, the renowned John Larkin wrote: On Sat, 2 Jun 2007 00:32:01 -0400, "Tom Del Rosso" wrote: "John Larkin" wrote in message Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. In the mid-80s there was a new PCB technology without vias. Traces just came to an end and disappeared into the board, with maximum density. What happened? There should be more demand for it than ever, and good yield should be possible by now if it was done 20 years ago. I saw some boards that looked like that, but they were just plated vias without annular rings. I think there were cracking problems where the trace dived into the hole. John Ah, I've seen those maybe once... (ummm intentionally, that is). They can do cool stuff like blind 5 thou microvias but the cost might be too much for many applications. Best regards, Spehro Pefhany What's standard these days? We're running 6 mil traces and 10 mil microvias, but "normal" keeps creeping down. One of our board houses does 4/4 mil lines spaces without extra charge and will go down to 3/3 mil (thou) lines spaces. They can do some really small micro vias with drill, and even much smaller with laser (as in via in fine pitch pad without problems). The boards are a little more expensive but the quality is generally top notch (we usually go to them with anything with more then 4 layers, fine traces, microvias, BGA's, generally anything more complex then usual PCBs. The boards don't sag badly during reflow, are very accurate, and the machines generally have very little problems building stacks of PCBs from them.) They have a location that may be close to you in California which is capable of true IPC level 3 boards, although we generally use a location that is more local to us. Email me if you want contact info. If I were you I would stick with the 6 mil traces, since plating and etching is not completely even over a large area, such as the boards you do, which could lower the yield of boards. If you need to go smaller, do it only in localized areas. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
No, it means that there are eight layers of etched copper foil. The
board is a sandwich, thin (like 1 mil) copper layers separated by insulating layers (8 mils maybe) of epoxy-glass. The two outer copper layers, "top" and "bottom" are on the surface, so you can solder parts to them. Sometimes you need all those layers to distribute all the power supplies and make all the connections. Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. Parts are usually all on the top side of the board, but if things get really dense sometimes people put parts on the bottom, too. Thanks John. I've been wondering about that for a while... |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Fri, 01 Jun 2007 22:27:59 -0400, tempus fugit wrote:
I know this is probably a stupid question, but does 8 layers mean the parts are on 8 different horizontal planes, all stacked on top of one another? Yes, this is a stupid question, considering it's a contextless response to the thread where John just showed me the 8 layers. In answer to your question, it's layers of copper within the board. Sheesh! Rich |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg - Pcb.jpg
2 Attachment(s)
On Mon, 4 Jun 2007 10:23:04 -0400, "tempus fugit"
wrote: No, it means that there are eight layers of etched copper foil. The board is a sandwich, thin (like 1 mil) copper layers separated by insulating layers (8 mils maybe) of epoxy-glass. The two outer copper layers, "top" and "bottom" are on the surface, so you can solder parts to them. Sometimes you need all those layers to distribute all the power supplies and make all the connections. Layers are connected by holes that are drilled through the board and metal-plated inside. Those are called "vias" and 2000 of them wouldn't be unusual. Parts are usually all on the top side of the board, but if things get really dense sometimes people put parts on the bottom, too. Thanks John. I've been wondering about that for a while... Here's a cross-section sample from a lot of 8-layer boards we did. John |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
"Michael A. Terrell" wrote in message
Was it just one bad via on one board, or a whole bad batch? Philco had a factory in Mexico that had lots of problems with consumer electronics, and Delco made a MAJOR design mistake when they used "Griplets" instead of plated through holes in a series of car radios. What makes eyelets or griplets so much less reliable? Expansion? I don't see a reason why they should break more than a connection to a lead does. Of course they have the disadvantage of only connecting outer layers. -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Mon, 4 Jun 2007 19:38:25 -0400, "Tom Del Rosso"
wrote: "Michael A. Terrell" wrote in message Was it just one bad via on one board, or a whole bad batch? Philco had a factory in Mexico that had lots of problems with consumer electronics, and Delco made a MAJOR design mistake when they used "Griplets" instead of plated through holes in a series of car radios. What makes eyelets or griplets so much less reliable? Expansion? I don't see a reason why they should break more than a connection to a lead does. Of course they have the disadvantage of only connecting outer layers. Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Mon, 04 Jun 2007 16:58:28 -0700, Jim Thompson
wrote: On Mon, 4 Jun 2007 19:38:25 -0400, "Tom Del Rosso" wrote: "Michael A. Terrell" wrote in message Was it just one bad via on one board, or a whole bad batch? Philco had a factory in Mexico that had lots of problems with consumer electronics, and Delco made a MAJOR design mistake when they used "Griplets" instead of plated through holes in a series of car radios. What makes eyelets or griplets so much less reliable? Expansion? I don't see a reason why they should break more than a connection to a lead does. Of course they have the disadvantage of only connecting outer layers. Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. --- Ultrasonics or X-rays won't work? -- JF |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
"Jim Thompson" wrote
in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
Tom Del Rosso wrote:
"Michael A. Terrell" wrote in message Was it just one bad via on one board, or a whole bad batch? Philco had a factory in Mexico that had lots of problems with consumer electronics, and Delco made a MAJOR design mistake when they used "Griplets" instead of plated through holes in a series of car radios. What makes eyelets or griplets so much less reliable? Expansion? I don't see a reason why they should break more than a connection to a lead does. Of course they have the disadvantage of only connecting outer layers. This was 30 some years ago, bu the Gripplets were supposed to be wave soldered to the boards after installation into the blank board. Vibration and heat cycling were blamed on making them intermittent. They sent out a field service order to run a wire through every one of them, bend it flush with the PC board and solder the wire to both sides of the boards on every radio serviced, no matter the reason the radio was pulled from a car. I think they were steel, and had fractured, If you heated them without putting a wire through and bending it over, they would fall out of the punched holes. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote:
"Jim Thompson" wrote in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. Vibration. The solder work-hardens and makes the joint unreliable. Hope This Helps! Rich |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
"Rich Grise" wrote in message
On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote: "Jim Thompson" wrote in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. Vibration. The solder work-hardens and makes the joint unreliable. But why is that different from any other joint? -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
Rich Grise wrote:
On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote: "Jim Thompson" wrote in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. Vibration. The solder work-hardens and makes the joint unreliable. Hope This Helps! Rich There is electro-migration away from the contact; lead does not work harden, it just migrates (more than aluminum). |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
On Tue, 05 Jun 2007 14:20:25 -0400, Tom Del Rosso wrote:
"Rich Grise" wrote in message On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote: "Jim Thompson" wrote in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. Vibration. The solder work-hardens and makes the joint unreliable. But why is that different from any other joint? It's the metal sandwich of the pad, solder, and eyelet surface - when the eyelet moves relative to the board, it puts a shear stress on the solder. "Ordinary" joints don't have that problem because the solder isn't squashed between two metal surfaces. Well, it sounds good to me. ;-) Cheers! Rich |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
"Rich Grise" wrote in message
It's the metal sandwich of the pad, solder, and eyelet surface - when the eyelet moves relative to the board, it puts a shear stress on the solder. "Ordinary" joints don't have that problem because the solder isn't squashed between two metal surfaces. Well, it sounds good to me. ;-) Ok, as long as nobody knows. :) -- Reply in group, but if emailing add another zero, and remove the last word. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
Rich Grise wrote:
On Tue, 05 Jun 2007 14:20:25 -0400, Tom Del Rosso wrote: "Rich Grise" wrote in message t On Mon, 04 Jun 2007 21:31:10 -0400, Tom Del Rosso wrote: "Jim Thompson" wrote in message Back in my discrete days I used copper eyelets for connecting large gauge high current wires. The military balk because the solder _under_ the eyelet can't be inspected. People always say they crack more, even if they're good initially. I don't know why that's so. Vibration. The solder work-hardens and makes the joint unreliable. But why is that different from any other joint? It's the metal sandwich of the pad, solder, and eyelet surface - when the eyelet moves relative to the board, it puts a shear stress on the solder. "Ordinary" joints don't have that problem because the solder isn't squashed between two metal surfaces. Well, it sounds good to me. ;-) Cheers! Rich Definitely, mechanical stress seems to enhance or aggrivate the migration of the solder. Monitors exhibit similar problems; one or more colors get intermittent and / or go out. One then must re-solder the CRT socket to the PCB. The mechanical stress comes from the sponge in the back of the case that presses on the metal cage around that PCB. I have fixed dozens of monitors that way, some 2 or three times. The one i have was bought 12-15 years ago and fixed 3 times so far. I have called it electomigration, because of the metal flow patterns with regard to presumed current flow in each trace. |
8-layer board, about 1050 parts - V470.jpg - V470snap.jpg
Robert Baer wrote:
Definitely, mechanical stress seems to enhance or aggrivate the migration of the solder. Monitors exhibit similar problems; one or more colors get intermittent and / or go out. One then must re-solder the CRT socket to the PCB. The mechanical stress comes from the sponge in the back of the case that presses on the metal cage around that PCB. I have fixed dozens of monitors that way, some 2 or three times. The one i have was bought 12-15 years ago and fixed 3 times so far. I have called it electomigration, because of the metal flow patterns with regard to presumed current flow in each trace. The problem is much simpler than that. The holes in the board are too big, and as a result, the solder is required to bridge a large gap. Solder has next to no ability to withstand repeated flexing, so the relatively thin solder bridge flexes and cracks. The answer is simple all joints should be good mechanical joints. The socket will last longer if you bend its pins outward so that they are leaning against the pad before you apply solder. -Chuck |
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