Basics about pick & place PCB design [closed]

Question

I've designed several PCB boards for different experimental products for the small company i work for.

Now it's time we move from experimental to actual production. So far the boards i've designed where sent to a manufacturer, and then i soldered every component myself (yeap, really small company).

I'm aiming for the next pcb to be sent for assembly with a pick & place machine, and i've never designed any board for this purpose, so i really don't know what considerations i have to keep in mind with such a design.

I need a detailed answer as to how to design boards for production with pick & place machine, and what are the most important facts to keep in mind. (I've searched the forum and couldn't find a "general" set of rules or tips, all answers are for particular questions and overlook general design criteria)

As a comment, right now if i placed components too close to each other or the design is too crowded of components, i can figure it out myself when soldering, or use some "tricks" all because i know every detail of the board, the intention here is that with the files i create anyone could send this board to manufacture and assembly, with no prior knowledge of the circuit. I hope i was clear as to what i'm asking, else comment and i'll elaborate a bit more.

Edit: All resistors and IC's are surface components, caps are of both types, there are some terminals and connectors, but 90% of the board is surface mount, so probably the through hole components could be soldered by hand.

Edit 2: I understand the answer to this might have to be too broad, maybe recommend a book regarding this topic?

I haven't decided the manufacturer, should i ask to all manufacturers in regards of their limitations? Surely there has to be some standards, or at the very least typical pick&place machine dimensions or default values as how many different component sizes allowed and the like.

Sidenote: I'm familiar with Altium Designer and Kicad, but if there's need of an extra software i have no problems in learning.

Answer 1

At the risk of giving a non-answer, have you considered asking the company that will be building the boards? You presumably have a potential manufacture in mind for these boards, if not then you probably should start looking before you get too far into the design process. Ask them what their design guidelines are. Moving to an outside board assembler isn't just buying a PCB with parts already on it, it requires a lot more interaction with the supplier than buying a blank board and a box of parts ever does.

Ultimately it comes down to two factors - how new/high spec the manufacturers system is and how much you want to pay.

You can pack 0201 parts in like crazy but it will limit you to manufacturers who can handle them and will cost you more since you need a better pick and place machine and both yield and reworkability will go down. Or you can go for a half inch clearance around every part and fiducials all over the place and they could dust off an old machine that's been sitting out the back unused for 10 years.

Also now is the time to think about production line testability. Do you want the assembler to do any testing beyond a visual inspection? If so what testing do you want, what are they capable of and what features need to be designed into the board to aid that testing?

So ultimately find a manufacturer and ask them what their guidelines are for maximizing yield. Some manufacturers may even have footprint guidelines they like you to follow. You don't always have to follow their guidelines to the letter but everything that improves yield is a good thing.

About the only truly universal guideline is to minimize your unique part count whenever practical. e.g. If you have 10k pull ups and 47k pull ups then if possible change them all to the same value, if you have some 5% parts and some 1% parts make them all 1%. Less reels of components that need to be loaded onto the machine will always reduce your cost.

Answer 2

Design For Manufacturing (DFM) aims to design a PCB which is reliable and feasible at minimum cost.

This means you need to know how the PCB manufacturing process and PCB assembly process are, steps involved, limitations of each PCB maker or assembler and how much you are willing to spend.

As many say this is a really big topic that can´t be covered in a single answer.

I would suggested the DFM videos of EEVBLOG as introduction

Part1 Part2 Part3