Why is 3D important in PCB design? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: May 26, 2015, 01:56:30 pm
content: I keep reading about how packages are not current if they lack being able to show a 3D image of a PCB, but my question is, why is this necessary? Does it matter? What does seeing a 3D version of the PCB accomplish?

author: c4757p
author_rank: Super Contributor
timestamp: May 26, 2015, 02:02:23 pm
content: It's of course possible to use really accurate (or, at least, height-accurate) 3D models for everything, and then use this to check clearance to enclosures and connectors and whatnot. Usually I'd guess people don't actually do this. I like to be able to produce a nice 3D render of the board, as yet another way of visualizing the final product, but that's just my personal preference, it doesn't really accomplish anything mechanical.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 26, 2015, 02:27:01 pm
content: Quote from: alank2 on May 26, 2015, 01:56:30 pmwith current era of 16 cores 4GHz cpu... with something that only can do command line is a waste of resources. not because you use it and waste it, but because you dont use it so it wait idle until the end of life. in current era imho, anything is not current if you cant make and edit a track in isometric real render 3d view, but i guess thats asking too much on the programmers side.Quote from: alank2 on May 26, 2015, 01:56:30 pmto cope with lazy generation and ever accelerating advancement in technology. one can do without it, but there will be alot "banging head on the wall" thing due to nonfitting components, wrong button placement relative to enclosure etc, and design to production cycle will consume more time than when you have the tool. its like asking, why we need matlab when we can solve partial differential equation with hand and paper?Quote from: alank2 on May 26, 2015, 01:56:30 pmyes it does, for the people who are doing the job requiring it. ie, a complete cycle from design to realization of the design, optimizing cost by reusing whats already there or standardized metric dimension thereis, that you cannot simply wish anything as you like. it doesnt matter if you only sit on only one side of the equation, ie designing the board in computer without reproducing it or fit it in something else tight, or you just let the other guy on the other side of the equation to bang their head for your mistake.Quote from: alank2 on May 26, 2015, 01:56:30 pmquick design to production cycle, hence more "profit" or "usefull work" per unit time.

author: ajb
author_rank: Super Contributor
timestamp: May 26, 2015, 02:47:50 pm
content: It's mainly about bridging the gap between ECAD and MCAD. If your PCB is only ever used on its own, or only has flying leads out to enclosure-mounted buttons and connectors, then the mechanical integration is pretty easy. Just cut the right profiles on the sides of the box where you want them, and done. On the other hand, if your board mounts to bosses on one side of the box and has right angle connectors that need to exit another side of the box, and maybe more connectors on a third side, then things get trickier. Sure, you could spend an hour or two with the manufacturer's drawings and a 2D plot of the board to figure it out, and you could get it done, but it would be a hell of a lot easier if you could export a solid model of the board, pull that straight into your MCAD program, and make cutouts directly off of the connector bodies. When you consider having to make revisions, and having to go through the whole process again when you need to move a connector, having native 3D becomes more and more attractive. Now add to that the ability to see how the rest of the board fits in the housing--is there adequate clearance for the wiring harnesses, how big of a battery can you fit, will you clear the LCD, etc. We're not even doing really tiny consumer or handheld devices or anything, and moving to Altium and SolidWorks has allowed us to become vastly better at design integration versus Eagle and AutoCAD, it makes a huge difference. And again, yeah, we could have done it with purely 2D tools and gotten to the same place, but it would have taken a lot more time and a bunch more prototyping to do it.Aside from that, even if you're not going to be putting your board in a box, having native 3D still helps make sure the board will go together the way you want. It makes it very easy to check that you'll have room to get a soldering iron in to those leads, or that there's finger room for that connector latch, and on and on.So is it necessary? No, strictly speaking, it's not, but then neither is PCB CAD--you could still tape out a board by hand if you wanted to. But I bet you don't want to.

author: dom0
author_rank: Super Contributor
timestamp: May 26, 2015, 03:29:34 pm
content: Quote from: Mechatrommer on May 26, 2015, 02:27:01 pmNo, that would be a huge PITA with more than one layer and would slow everything down, too. For laying stuff out you really want 2D only.

author: georges80
author_rank: Frequent Contributor
timestamp: May 26, 2015, 04:13:00 pm
content: As per AJB, exactly right.I haven't found the need for 3d rendering within a PCB layout package, but it is very useful to be able to export the layout along with component height information to a file that solidworks can import. Then the mechanical engineer can import the file and visualise how the board will fit within a housing and this is not a simple box, but something that has clips and supports and switch plastic etc that has to fit exactly with the PCB assembly. Even more important when the housing contains multiple boards that need to connect together and to other things.cheers,george.

author: ConKbot
author_rank: Super Contributor
timestamp: May 26, 2015, 05:07:57 pm
content: IMO one of the biggest benefits to 3d in a PCB package, to the PCB designer, is that when you are making footprints, if the model is from a different source than your footprint (i.e. you didnt make both from the datasheet) then you get a verification of your footprint without having to do the ol print out the layout and sit parts on it to double check before you sent it off for fab. Especially helpful if you dont have the parts in hand yet. Even if they both are from the same source, constructing a 3d model of a package in solidworks is of a much different method than laying out a footprint, so youre not likely to make the same mistake twice and have an incorrect package fit perfectly on the incorrect footprint.

author: free_electron
author_rank: Super Contributor
timestamp: May 26, 2015, 05:14:25 pm
content: It is NOt the 3D visualisation that is important . That is only eye-candy and serves no purpose.It is the capability of the program to check spatial positionin gin 3D that is important. Verifiying that no components will touch each other , touch the case, wanted or unwanted. Combine that with interaction capability with mechaincal world : loading the case for example, and exporting the pcb , with components, in a machine readable 3d format so the alignment of connectors in the case will be right. The lightpipe will mate with the led on the board etc .3D is only usefull if you can actually EDIT in 3d mode. : meaning you can position parts while in 3d view. And the program tells you on the fly if you have collisions or not. Begin able to generate a synthtic image through a renderer is pretty much useless and only good for showing a picture.the real power lies in the interation with the mechanical world.Very advanced programs allow you to design flxible or rigid-flex boards , where you can actually bend the flex to check the end result will work correctly. I did a little board that has three flex sections , two have a pushbutton , the third a pushbutton and an antenna. This thing mates with a plastic base shell that has a battery holding clip. And then there is an outer shell that encapsulates this whole construction. The end result looks like a little car. You can push the nose, trunk , roof , and side doors. due to the very small form factor ( the size of a 'matchbox' car ) this board needed rigid-flex. everything snaps together with clips molded in the plastic pieces ( no screws ). The mechanical people designed the body shells , i extracted usable space for parts , can figure out what part can go where , folded the board , sent back the pacb design and the created the internal support structure for my board.we sent the cad data to a 3d printer that printed the outer shell, the inner structure and a 3d model of the pcb including parts. everything fit perfect on the first try. so we ordered the dies for the plastic injection molding and the pcb's.That is why 3D is necessary in PCB design. Getting things first time right. just 'darwing interconnections on a plane is not board ' design'. it is only a subpart of the entire design cycle.Designing a board is everythign from schematic capture, simulation o the schematic, part placement, board material selection , assembly techniques , soldering tecniques, multilayers, blind and buried, laser vias, flex , downt checkign the routing for parasitics, cross coupling , impedance, termination and making sure the mounting holes are in and the damn thing fits the box it needs to go in to.3D editing and realtime visualisation is a big help in certain of these area's. It speed sup the process and eliminates errors.Couple that with file exchange of 3d models and you have a big advantage in both time and reduction of possible mistakesOffline rendering ( non realtime) is only good for eye-candy. And i will be the first to just shrug at tools that do this offline eyecandy stuff through a renderer. that is useless. (apart for marketing purposes)

author: john_p_wi
author_rank: Regular Contributor
timestamp: May 26, 2015, 05:17:57 pm
content: Quote from: georges80 on May 26, 2015, 04:13:00 pmAdditionally, it allows measuring creepage and clearance distances to mating surfaces of housings etc to meet the appropriate regulations. As packaging becomes smaller and more densely packed 3D models are essential.

author: free_electron
author_rank: Super Contributor
timestamp: May 26, 2015, 05:20:39 pm
content: Quote from: dom0 on May 26, 2015, 03:29:34 pmyou try creating a board stack for a 14 layer board which uses stacked laser via's on the outer two layers ( top ,1,13 and bottom) and burieds between 1 and 13 WITHOUT 3d visualisation of the via's and traces and see how far you will get making a layout that has enough channel space to route it. especially once you start to need shaving the inn pads around thevia's if they are not connected on that layer.3D is a very big help in setting that up and getting it right the first time as you can really see what the end cross section of the board will look like , as opposed to a topside only view.For a simply 2 layer board you won;t need that, but to do anything like a smartphone board or tabled main board .... you bet you want 3D .

author: John_ITIC
author_rank: Frequent Contributor
timestamp: May 26, 2015, 05:40:30 pm
content: Quote from: alank2 on May 26, 2015, 01:56:30 pmI find it very useful to check all high-speed transmission lines in my PCBs with the 3D view. High-speed differential SERDES lines cannot have stubs without degrading the signal integrity. Mistakes like using a through-hole via while a blind via was intended are very easy to make in 2D view but is easy to detect in 3D view due to the stub that is formed. I therefore verify that everything looks like intended before generating gerbers. In fact, I always check all tracks in 3D view before manufacturing PCBs./John.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 26, 2015, 08:06:40 pm
content: Quote from: free_electron on May 26, 2015, 05:14:25 pmiirc this is the 2nd time i heard from you.. so it is usefull for marketing purpose, right? you are not marketing thats why you says so, until marketing chaps knocking your shoulder asking for 3d render, he ask you because the boss ask him to...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 26, 2015, 09:57:41 pm
content: Quote from: free_electron on May 26, 2015, 05:14:25 pmIn deference to Mr. F. E., the 3D visualization IS important.All valid points, though: having PCB to Mech. interaction is paramount for projects where tight placement and packaging is necessary.Personally, I feel I have a better grasp of the board if I can turn it around, visually -- still not quite the same as turning around one in your hands, physically, but I feel it gives a better perception of placement and layout. Which in turn applies to placement rules (clearances for placement, rework), mechanical form factor, electromagnetic design of the board, and so on.I would be perfectly capable of making as-good designs without 3D whatsoever, if that's something else you're wondering -- that may or may not be relevant to a newbie or rookie rather than an expert, so YMMV. I would say the experience is different, and as a result, you'll make at least slightly different layouts, for whatever possible reasons.Tim