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From: Rich Grise on 11 Aug 2010 19:13 On Tue, 10 Aug 2010 09:06:20 -0700, John Larkin wrote: > On Tue, 10 Aug 2010 17:20:29 +0200, Fred Bartoli <" "> wrote: > >>Why are the so called PCB design experts just mouse shakers? >> >>Why does this have to happen during my holidays? > > Is the mouser distant from you? That's often a disaster. I prefer to > keep the layout-er in the next cube, and stay close. > > Best next thing is to have a copy of his/her software and shoot the > files back and forth often. I usually do the initial placement and the > critical routing on, say, one channel, and stay close to the layout as > it progresses. > > Some layout people place parts based on the rubberbands. That's > usually a disaster. They have to place based on the schematic. > > Layer-layer crosstalk, trace widths, mechanical, thermal, pinouts... > too many ways to mess up. > > I've always found women to be the best layout people. They seem to > listen better. > I once designed a little board with about a half-dozen chips, gave the schematic to one of the assemblers, and she followed the schematic so accurately that she put a half-dozen capacitors in parallel, right next to each other, at the power inlet to the board. I explained that that's just a schematic convention, and it was supposed to be one cap per chip; I didn't have to revise the schematic, but it took her about 1/2 hour to add the other caps. She was also kinda relieved that since they're just bypass caps, the bank of them at the connector would do no harm, and could be left in place. ;-) (it was a one-off, so no big deal.) Cheers! Rich
From: Robert Baer on 12 Aug 2010 04:36 Phil Hobbs wrote: > John Larkin wrote: >> On Tue, 10 Aug 2010 17:20:29 +0200, Fred Bartoli <" "> wrote: >> >>> Why are the so called PCB design experts just mouse shakers? >>> >>> Why does this have to happen during my holidays? >> >> Is the mouser distant from you? That's often a disaster. I prefer to >> keep the layout-er in the next cube, and stay close. >> >> Best next thing is to have a copy of his/her software and shoot the >> files back and forth often. I usually do the initial placement and the >> critical routing on, say, one channel, and stay close to the layout as >> it progresses. >> >> Some layout people place parts based on the rubberbands. That's >> usually a disaster. They have to place based on the schematic. >> Layer-layer crosstalk, trace widths, mechanical, thermal, pinouts... >> too many ways to mess up. >> >> I've always found women to be the best layout people. They seem to >> listen better. >> >> John >> > > Just had a slightly similar issue with a customer--an engineer who was > on his way out the door ditched the 0603 metal film resistors in favour > of 0402 thick films without telling anyone...>30 dB noisier down in the > 1/f region where we're working. > > There was plenty of room for the 0603s, but nooooo, he had to be creative. > > :( > > What a maroon. There may be enough pad space to bodge in 0603s for the > demo--I sure hope so. > > Cheers > > Phil Hobbs > > > > > Lay the resistors in on edge; saves horizontal space and trace length may be more than sufficient to compensate on length.
From: John Larkin on 12 Aug 2010 10:23 On Thu, 12 Aug 2010 01:36:44 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >Phil Hobbs wrote: >> John Larkin wrote: >>> On Tue, 10 Aug 2010 17:20:29 +0200, Fred Bartoli <" "> wrote: >>> >>>> Why are the so called PCB design experts just mouse shakers? >>>> >>>> Why does this have to happen during my holidays? >>> >>> Is the mouser distant from you? That's often a disaster. I prefer to >>> keep the layout-er in the next cube, and stay close. >>> >>> Best next thing is to have a copy of his/her software and shoot the >>> files back and forth often. I usually do the initial placement and the >>> critical routing on, say, one channel, and stay close to the layout as >>> it progresses. >>> >>> Some layout people place parts based on the rubberbands. That's >>> usually a disaster. They have to place based on the schematic. >>> Layer-layer crosstalk, trace widths, mechanical, thermal, pinouts... >>> too many ways to mess up. >>> >>> I've always found women to be the best layout people. They seem to >>> listen better. >>> >>> John >>> >> >> Just had a slightly similar issue with a customer--an engineer who was >> on his way out the door ditched the 0603 metal film resistors in favour >> of 0402 thick films without telling anyone...>30 dB noisier down in the >> 1/f region where we're working. >> >> There was plenty of room for the 0603s, but nooooo, he had to be creative. >> >> :( >> >> What a maroon. There may be enough pad space to bodge in 0603s for the >> demo--I sure hope so. >> >> Cheers >> >> Phil Hobbs >> >> >> >> >> > Lay the resistors in on edge; saves horizontal space and trace length >may be more than sufficient to compensate on length. Can you p+p and reflow resistors on edge? John
From: Robert Baer on 13 Aug 2010 04:25 John Larkin wrote: > On Thu, 12 Aug 2010 01:36:44 -0700, Robert Baer > <robertbaer(a)localnet.com> wrote: > >> Phil Hobbs wrote: >>> John Larkin wrote: >>>> On Tue, 10 Aug 2010 17:20:29 +0200, Fred Bartoli <" "> wrote: >>>> >>>>> Why are the so called PCB design experts just mouse shakers? >>>>> >>>>> Why does this have to happen during my holidays? >>>> Is the mouser distant from you? That's often a disaster. I prefer to >>>> keep the layout-er in the next cube, and stay close. >>>> >>>> Best next thing is to have a copy of his/her software and shoot the >>>> files back and forth often. I usually do the initial placement and the >>>> critical routing on, say, one channel, and stay close to the layout as >>>> it progresses. >>>> >>>> Some layout people place parts based on the rubberbands. That's >>>> usually a disaster. They have to place based on the schematic. >>>> Layer-layer crosstalk, trace widths, mechanical, thermal, pinouts... >>>> too many ways to mess up. >>>> >>>> I've always found women to be the best layout people. They seem to >>>> listen better. >>>> >>>> John >>>> >>> Just had a slightly similar issue with a customer--an engineer who was >>> on his way out the door ditched the 0603 metal film resistors in favour >>> of 0402 thick films without telling anyone...>30 dB noisier down in the >>> 1/f region where we're working. >>> >>> There was plenty of room for the 0603s, but nooooo, he had to be creative. >>> >>> :( >>> >>> What a maroon. There may be enough pad space to bodge in 0603s for the >>> demo--I sure hope so. >>> >>> Cheers >>> >>> Phil Hobbs >>> >>> >>> >>> >>> >> Lay the resistors in on edge; saves horizontal space and trace length >> may be more than sufficient to compensate on length. > > Can you p+p and reflow resistors on edge? > > John > I do not think a P+P machine can "turn" a part, i think it can only rotate based on how it is in the tape reel. Reflow works, once placed..
From: krw on 13 Aug 2010 18:22
On Fri, 13 Aug 2010 01:25:10 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >John Larkin wrote: >> On Thu, 12 Aug 2010 01:36:44 -0700, Robert Baer >> <robertbaer(a)localnet.com> wrote: >> >>> Phil Hobbs wrote: >>>> John Larkin wrote: >>>>> On Tue, 10 Aug 2010 17:20:29 +0200, Fred Bartoli <" "> wrote: >>>>> >>>>>> Why are the so called PCB design experts just mouse shakers? >>>>>> >>>>>> Why does this have to happen during my holidays? >>>>> Is the mouser distant from you? That's often a disaster. I prefer to >>>>> keep the layout-er in the next cube, and stay close. >>>>> >>>>> Best next thing is to have a copy of his/her software and shoot the >>>>> files back and forth often. I usually do the initial placement and the >>>>> critical routing on, say, one channel, and stay close to the layout as >>>>> it progresses. >>>>> >>>>> Some layout people place parts based on the rubberbands. That's >>>>> usually a disaster. They have to place based on the schematic. >>>>> Layer-layer crosstalk, trace widths, mechanical, thermal, pinouts... >>>>> too many ways to mess up. >>>>> >>>>> I've always found women to be the best layout people. They seem to >>>>> listen better. >>>>> >>>>> John >>>>> >>>> Just had a slightly similar issue with a customer--an engineer who was >>>> on his way out the door ditched the 0603 metal film resistors in favour >>>> of 0402 thick films without telling anyone...>30 dB noisier down in the >>>> 1/f region where we're working. >>>> >>>> There was plenty of room for the 0603s, but nooooo, he had to be creative. >>>> >>>> :( >>>> >>>> What a maroon. There may be enough pad space to bodge in 0603s for the >>>> demo--I sure hope so. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>>> >>>> >>>> >>>> >>>> >>> Lay the resistors in on edge; saves horizontal space and trace length >>> may be more than sufficient to compensate on length. >> >> Can you p+p and reflow resistors on edge? >> >> John >> > I do not think a P+P machine can "turn" a part, i think it can only >rotate based on how it is in the tape reel. > Reflow works, once placed.. Any yaw, no roll or pitch. ;-) |