Dan,
We have been using reflow on both sides for many years now. Most of the products we design would need double PCB area if we were not allowed to place SMDs on both surface layers. Pedro, your point is good, it manages to clear things for me. I was confused because for me, the natural order of layers would be counting them incrementally from top to bottom like this: Top layer = Top Layer for axial and SMD Next Layer=Inner1 Next Layer=Inner2 ... ... ... One before last=Inner14 Bottom Layer=Bottom Layer for SMD This is how other dedicated PCB design environments count the layers (OrCAD for instance). Based on what you say and from my observations, In KiCAD the count is somehow reversed. Don't you find this a little...un-natural? Regards, Cristian --- On Sun, 2/8/09, Pedro Martin <[email protected]> wrote: From: Pedro Martin <[email protected]> Subject: Re: [kicad-users] layer stack-up question To: [email protected] Date: Sunday, February 8, 2009, 1:01 PM Hi Dan, Christian, Viewing the pcb on my working table: -Top layer = components layer, for axial components and smd. -Next layer = 15 layer=Inner_L14 -... -Last but one= 2 layer = Inner_L1 -Bottom layer = soldering or copper layer. Anyway, both top and bottom are called copper layers (plural) because both layers are the only ones allowing copper. Copper layer (singular) is always bottom layer. When creating vias, you must define the pair of layers for the via. And be careful with your pcb maker. For example, for pcbexpress numbering is top, inner_1, inner_2 and bottom in a 4 layer pcb. In pcbnew standard colours, bottom is green and top is red. All green texts are inverted. I have never used buried or blind vias because of the low yield of pcbmakers, which means high prices. And, Dan, nowadays there are some manufacturers that mount smd in both sides... regards, Pedro. > Hi Dan, thanks for the reply. > > I did a little experiment that would seem to contradict what you are saying. I routed a track on the "copper" layer and then I placed a microvia. The router tool automatically changed to Inner_L1. For me, this means that "copper" is on top. > I confirmed this by routing a track on the "component" layer. I then placed a microvia and the routing tool changed to Inner_L14. For me, this would indicate that component is on bottom. > > All these are proofs to the extent to which we accept that Inner_L1 is immediately below the Top layer and that Inner_L14 is immediately above bottom layer. > > In addition, the attached screencapture would also suggest that "copper" is top and "component" is bottom. > > Still, this would not explain why in the libraries yo find the smd components defined on "component" layer, so this would indicate you being right, and my experiments being wrong. > > Has anybody encountered any problems when using blind or buried vias? > > Regards, > Cristian > > --- On Sat, 2/7/09, Dan Andersson <[email protected]> wrote: > From: Dan Andersson <[email protected]> > Subject: Re: [kicad-users] layer stack-up question > To: [email protected] > Date: Saturday, February 7, 2009, 3:47 PM > > The "copper" layer is the bottom layer and it's more natural to > see it as such > when designing with axial components. > > The upper surface layer is called "component" layer. > > This is a surviving description from the pre-smd age. > > The reason for mirroring text on the copper layer i that you are looking on > the pcb from above, you are looking trough your component layer as your > viewpoint is above the top of the pcb board. > > The defacto standard of mounting SMD's is on the top - component side. > > YOU DO NOT PLACE SMD ON BOTH SIDES! Unless you solder it by hand. > > //Dan, M0DFI > > > On Saturday 07 February 2009 12:26:37 Berceanu Cristian wrote: > > Hi, > > I have only recently started to use KiCAd and I think it is great. > > However, I encountered some...contradictions. I am having trouble in > > understanding which is the Top layer and which is the Bottom Layer. In > > the help of Pcbnew I found the following statements: > > > > 1. "They are the usual layers of work, used by the automatic router, > > on which tracks can be placed. Layer 1 is the copper (solder) layer. > > Layer 16 is the component layer. The other layers are the internal > > layers (L2 to L15)." > > > > 2. "All text on the 'copper' (sometimes called > 'solder' or 'bottom') > > side must be mirrored." > > > > For me, the first statement would indicate that the layer called > > "copper" is the top layer. But the second statement says that > "copper" > > is the bottom layer. If the "copper" is the bottom layer, then > it > > comes in contradiction not only with statement 1, but also with the > > fact that the SMD footprints in the library have their pads defined on > > the "component" layer (and normally, one would expect the SMDs > to be > > defined by default on top, and only when you mirror them, they get on > > bottom). > > > > So...which is Top and which is Bottom? > > > > Thank you for your help! > > > > Regards, > > Cristian > > > > ------------------------------------ > > Please read the Kicad FAQ in the group files section before posting your > question. > Please post your bug reports here. They will be picked up by the creator of > Kicad. > Please visit http://www.kicadlib.org for details of how to contribute your > symbols/modules to the kicad library. > For building Kicad from source and other development questions visit the > kicad-devel group at http://groups.yahoo.com/group/kicad-develYahoo! Groups > Links > > > > > > > ------------------------------------ Please read the Kicad FAQ in the group files section before posting your question. Please post your bug reports here. They will be picked up by the creator of Kicad. Please visit http://www.kicadlib.org for details of how to contribute your symbols/modules to the kicad library. For building Kicad from source and other development questions visit the kicad-devel group at http://groups.yahoo.com/group/kicad-develYahoo! Groups Links required)
