DFM

PCB process the design must survive

Leo designs schematic and layout, and reviews the same sequence a fab and SMT line will run. We do not run a factory. This is what the board has to live through.

Bare board

01CAM and DFM incomingThe fab reads Gerber, drill and stack-up before copper is touched. Most boards that fail in SMT already failed here.02Inner layer image and etchOn multilayer boards the inner copper is printed and etched first. Two-layer ESP32 boards skip this step.03Lay-up and laminationCores and prepreg are stacked and pressed into one multilayer panel. Thickness and warp are set here.04DrillingHoles for vias, PTH and mounting. Aspect ratio and min hole decide whether the quote is real.05PTH and copper plateThe hole wall gets copper so layers connect. This is the difference between a via and a decorative hole.06Outer pattern and etchOuter copper is imaged and etched to the tracks you drew. Fine pitch ESP32 modules live or die on remaining copper.07Solder maskMask keeps solder on the pads. Dams between ESP32 pins are a process, not a colour choice.08Legend / silkscreenInk that tells a human which way the part goes. It does not carry current, but it saves first-article hours.09Surface finishENIG, HASL or OSP on the pads. For ESP32 RF and fine pitch, the finish is a design choice, not a cheaper checkbox.10Outline, V-cut and depanelThe board is cut from the panel. Mouse-bites and V-score are mechanical design, not leftovers.11Electrical test of the bare boardFlying probe or fixture checks the netlist before SMT. It does not prove your schematic, only the copper.

Assembly

12Stencil and solder pastePaste volume is set by aperture and foil thickness. QFN and ESP32 modules fail here more often than in the pick-and-place program.13Pick and placeParts land on paste. Polarised parts, ESD and the ESP32 module rotation are the boring failures that cost a week.14ReflowPaste melts and joints form. Profile, warpage and voids under the ESP32 pad show up here.15SPI, AOI and X-rayMachines look at paste, parts and hidden joints. They do not replace a UART log on first bring-up.16First article and bring-upPower, flash and the first UART. This is the landing step we sell — after the factory process, not instead of it.

Leo · WhatsApp +86 17052886709

中文

DFM

设计必须过得去的 PCB 工艺

Leo 画原理图和布局，并对照板厂和 SMT 线会走的同一条顺序。我们不开工厂。这是板子必须活下来的路径。

光板

01CAM 与 DFM 来料工厂在动铜之前先读 Gerber、钻孔和叠层。很多 SMT 才爆的问题，这里已经埋下了。02内层图形与蚀刻多层板先做内层曝光蚀刻。两层 ESP32 板没有这一步。03叠层与压合芯板和半固化片压成多层板。板厚和翘曲在这里定下来。04钻孔过孔、金属化孔、安装孔。孔径比和最小孔决定报价是不是真能做。05沉铜与电镀孔壁上铜，层间才导通。这是过孔和装饰孔的差别。06外层图形与蚀刻外层按你画的线蚀出来。细间距 ESP32 模组看的是蚀完还剩多少铜。07阻焊阻焊把锡留在焊盘上。ESP32 脚之间的阻焊桥是工艺，不是选颜色。08丝印给人看装哪一面、哪一脚。不导电，但能省掉首件几小时。09表面处理焊盘做沉金、喷锡或 OSP。ESP32 射频和细间距这是设计选择，不是勾最便宜那一项。10外形、V 割与分板从拼板上把板切下来。邮票孔和 V 割是结构设计，不是边角料。11光板电测飞针或针床按网络表测开短路。它不证明原理图对，只证明铜对。

组装

12钢网与锡膏锡量由开口和钢网厚度决定。QFN 和 ESP32 模组死在这里的，比死在贴片程序上的多。13贴片器件落到锡膏上。极性、静电、ESP32 模组方向，都是能耗掉一周的无聊故障。14回流焊锡膏熔化成焊点。温度曲线、翘曲、ESP32 大焊盘空洞，都在这里出现。15SPI、AOI 与 X-ray机器看锡、看件、看隐藏焊点。代替不了第一次点亮的串口日志。16首件与点亮电源、烧录、第一次串口。这是我们卖的落地步骤——在工厂工艺之后，而不是代替工厂。

Leo · WhatsApp +86 17052886709