Re: [PEDA] Annular Ring question, via question
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** At 04:15 PM 10/3/01 -0400, Jeff Adolphs wrote: 1. Since I am using a small via to make routing SMT easier. Small via having a 10 mil dia. annular ring (pad of 31_21). Ah, the confusion of it! Annular ring in the industry means the radial difference between the hole wall and the outside edge of the pad. Protel, somewhere back there, got it completely wrong. They have fixed it in some places and not in others. The described via has a 5 mil annular ring. This is not an uncommon situation for vias. One might expect to pay a premium, but not much. Am I free to reduce the annular ring on other parts without any harm. Specificly, reducing a Pad of 75 with a drill of 43, to a Pad of 61 with a drill of 43? A pad of 61_43 would make a connector much easier to route. 60/40 is a very common pad/hole size, it works for 25 mil square posts. The hole size which should be used in Protel is the *finished size*. With a 10 mil annular ring, this is standard production. I don't recommend going below 10 mil ring for soldered components, i.e., 20 mil diametric oversize. Board info: So far I'm trying to keep the PCB at space 9 mil minimum, trace of 9 mil minimum. This is overkill. 8/8 has been standard production for a long time, I've been told that 7/7 is also no problem, things start to get dicier at 6/6 but that is still common. Below that things get more difficult for the fabricator. 4/4 is pretty much the finest I've seen advertised for normal production materials. 2. Will I save money by using a Via of 31_21 only when necessary and using a Via of 50_28 everywhere else. Maybe, maybe not. By the way, you might be able to use a via of 25/15 if you need it. I've seen plenty of boards with this small a hole and via. A 15 mil hole is drilled oversize at 18 mils and comes back to 15 with the plating (just like a 40 mil nominal hole is drilled 43 mils nominal). [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Annular Ring question, via question
Re: [PEDA] Annular Ring question, via question
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** On 12:11 PM 4/10/2001 -0700, Abd ul-Rahman Lomax said: This is overkill. 8/8 has been standard production for a long time, I've been told that 7/7 is also no problem, things start to get dicier at 6/6 but that is still common. Below that things get more difficult for the fabricator. 4/4 is pretty much the finest I've seen advertised for normal production materials. There is a company in Oz that will do 0.05mm tracks and spaces (2 mils) as a special on FR4. Their process is unusual. Substrate is plasma coated to 2 micrometre. The etching is don on this tiny layer and then plating is performed. They claim much lower undercut, edge smoothness and the results I have seen support this. These are the best looking board I have seen. They have been doing this for years - I used to get some RF boards on really soft soggy material done by them, including almost complete edge plating. http://www.lintek.com.au for those interested. Ian Wilson * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Annular Ring question, via question
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** At 02:22 PM 10/4/01 -0400, [EMAIL PROTECTED] wrote: My experience with fabricators has been quite the opposite, that I want to specify the actual drill size, after having made an allowance for plating thickness where I need to mount things in the holes. If you use finished size, the fabricator must bump up the drill size to account for plating thickness, and then all your carefully checked clearances go out the window. They go out the window anyway, since you don't have so much control over the plating. Specifying the actual drill size can have some value, because the hole then represents the limits of the metal; but the norm in fabrication drawings is finished size, which is pretty much all you can easily check. Metalization limit is only going to help you if you section boards or use other hi-tech inspection methods (because metalization only matters on inner layers when you remove the pads, otherwise we are talking about a 1.5 mil annular ring, so it is normally swallowed in the pad. It is then up to the fabricator to take the rest of your specifications into account and choose the appropriate drill size to meet your tolerances on the finished size. [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Annular Ring question, via question - Now PCB quoting
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** At 02:47 PM 10/4/01 -0400, Jeff Adolphs wrote: Didn't Abd ul-Rahman used to be in California? MA is quite a long distance move! Especially when you drive through Canada, as we did. I was born in California but haven't missed it yet. Western Massachusetts is a pleasure every day. Yes, I know winter is coming, but, ya know, we don't have winter in California and that is *not* an advantage. Now, where were we? Yes, ask your fabricator. They don't charge for answering questions! [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Annular Ring question, via question
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** Jeff: First step for a question like this should be your board house. They should be able to tell you right off the bat whether there will be any impact on their yield (read: cost to you) with the lower annular ring. Another alternative would be to drop your trace widths and clearances. 9/9 is very generous - most board shops will do at least 8/8 with no cost penalty, while 6/6 is also not unusual for high performance shops without yields suffering (bleeding edge at 4/4 and below is another story...). As an example, one of my local (ordinary quality) board shops has a standard set of design rules (i.e. high yield expectations) that include: 0.15mm (0.006) track width 0.15mm (0.006) tack spacing 0.25mm (0.010) annular ring With this shop, I regularly do 0.175mm (0.007) annular rings (by mutual agreement), and with a consequent yield impact (i.e. I'm happy to pay the extra cost). If you do drop your annular ring below the board shop's accepted standard, then you should restrict the use of these pads/vias to only the locations necessary. The more instances of exceptions to rules that exist on the board, the higher statistical probability of a board failing in mfr. Remember that the principal reason for min. annular ring specifications is to guard against drill breakout. There are alternative design techniques that can allow you to shrink the annular ring, by allowing controlled breakouts (usually on interior layers) without sacrificing board performance. For example, teardropping to a pad provides a guard against breakout on the side of the connection. (If you use this or other techniques you'll need to give your board shop explicit permission to allow breakouts) Hope this helps, John Haddy -Original Message- From: Jeff Adolphs [mailto:[EMAIL PROTECTED]] Sent: Thursday, 4 October 2001 6:15 AM To: Protel EDA Forum (E-mail) Subject: [PEDA] Annular Ring question, via question Cheers Protel Group! 1. Since I am using a small via to make routing SMT easier. Small via having a 10 mil dia. annular ring (pad of 31_21). Am I free to reduce the annular ring on other parts without any harm. Specificly, reducing a Pad of 75 with a drill of 43, to a Pad of 61 with a drill of 43? A pad of 61_43 would make a connector much easier to route. Board info: So far I'm trying to keep the PCB at space 9 mil minimum, trace of 9 mil minimum. 2. Will I save money by using a Via of 31_21 only when necessary and using a Via of 50_28 everywhere else. Thanks in advance! Jeff Adolphs Lake Shore Cryotronics, Inc Westerville, Ohio, USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Annular Ring question, via question
*** Todays forums are sponsored by Ian Martin Limited Engineering/Technical Placement Specialists www.ianmartin.com *** Jeff, I agree with everything John states below. It is well written and good advice. Also consider the smallest drill to board thickness, a.k.a. aspect ratio, that will change the price of building your design at the board house. A related issue is the count of different sized holes made by your design. Cheers! Drew - Original Message - From: John Haddy [EMAIL PROTECTED] To: Protel EDA Forum [EMAIL PROTECTED] Sent: Wednesday, October 03, 2001 5:01 PM Subject: Re: [PEDA] Annular Ring question, via question Jeff: First step for a question like this should be your board house. They should be able to tell you right off the bat whether there will be any impact on their yield (read: cost to you) with the lower annular ring. Another alternative would be to drop your trace widths and clearances. 9/9 is very generous - most board shops will do at least 8/8 with no cost penalty, while 6/6 is also not unusual for high performance shops without yields suffering (bleeding edge at 4/4 and below is another story...). As an example, one of my local (ordinary quality) board shops has a standard set of design rules (i.e. high yield expectations) that include: 0.15mm (0.006) track width 0.15mm (0.006) tack spacing 0.25mm (0.010) annular ring With this shop, I regularly do 0.175mm (0.007) annular rings (by mutual agreement), and with a consequent yield impact (i.e. I'm happy to pay the extra cost). If you do drop your annular ring below the board shop's accepted standard, then you should restrict the use of these pads/vias to only the locations necessary. The more instances of exceptions to rules that exist on the board, the higher statistical probability of a board failing in mfr. Remember that the principal reason for min. annular ring specifications is to guard against drill breakout. There are alternative design techniques that can allow you to shrink the annular ring, by allowing controlled breakouts (usually on interior layers) without sacrificing board performance. For example, teardropping to a pad provides a guard against breakout on the side of the connection. (If you use this or other techniques you'll need to give your board shop explicit permission to allow breakouts) Hope this helps, John Haddy -Original Message- From: Jeff Adolphs [mailto:[EMAIL PROTECTED]] Sent: Thursday, 4 October 2001 6:15 AM To: Protel EDA Forum (E-mail) Subject: [PEDA] Annular Ring question, via question Cheers Protel Group! 1. Since I am using a small via to make routing SMT easier. Small via having a 10 mil dia. annular ring (pad of 31_21). Am I free to reduce the annular ring on other parts without any harm. Specificly, reducing a Pad of 75 with a drill of 43, to a Pad of 61 with a drill of 43? A pad of 61_43 would make a connector much easier to route. Board info: So far I'm trying to keep the PCB at space 9 mil minimum, trace of 9 mil minimum. 2. Will I save money by using a Via of 31_21 only when necessary and using a Via of 50_28 everywhere else. Thanks in advance! Jeff Adolphs Lake Shore Cryotronics, Inc Westerville, Ohio, USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
