PCB / Electrical test of the bare board

Bare board · 11

Electrical test of the bare board

Flying probe or fixture checks the netlist before SMT. It does not prove your schematic, only the copper.

01 What happens

  • The tester compares the board to the CAM netlist: opens, shorts, missing nets.
  • Flying probe is right for prototypes. A bed-of-nails fixture pays off in volume.
  • Unconnected pads, antenna copper and NPTH are special cases — they must be in the test program on purpose.

02 On an ESP32 board

  • An ESP32 antenna pour that is not a net will look like an island. That is often correct.
  • Test pads for UART and power save first-article time; they are also what the fixture hits later.
  • E-test will not catch a wrong footprint if copper matches the Gerber.

03 What usually fails

  • False fails on fine pitch, or skipped nets on a cheap ‘sample, no E-test’ lot.
  • Program built from the wrong revision Gerber.
  • Assuming E-test means the board will boot.

04 What we check

  • Prototype lots should include E-test unless we accept the risk in writing.
  • We still do first bring-up. Copper continuity is not firmware.

← Previous step: Outline, V-cut and depanelNext step: Stencil and solder paste →

中文

PCB工艺 / 光板电测

光板 · 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。

01 这一步做什么

  • 和 CAM 网络表比：开路、短路、缺网。
  • 样板用飞针。上量再做针床。
  • 天线铜皮、NPTH、孤立盘要在程序里故意处理。

02 落到 ESP32 板上

  • ESP32 天线铜经常不是一个网，测起来像孤岛，往往是对的。
  • UART 和电源测试点既方便首件，也方便以后针床。
  • 封装错了但铜和 Gerber 一致，电测过不了这一关。

03 常见失败

  • 细间距误报，或便宜样板「不测电」。
  • 程序用了旧版 Gerber。
  • 以为电测过了就能开机。

04 我们查什么

  • 样板默认要电测，除非书面接受风险。
  • 仍然要做点亮。铜通了不是程序通了。

← 上一步: 外形、V 割与分板下一步: 钢网与锡膏 →