PCB / Pick and place

Assembly · 13

Pick and place

Parts land on paste. Polarised parts, ESD and the ESP32 module rotation are the boring failures that cost a week.

01 What happens

  • The machine uses centroid (XYR) and feeder setup. Vision checks fiducials on the panel.
  • Fine-pitch and BGA/QFN need good fiducials and a true centroid, not a silk centre.
  • Moisture-sensitive parts (including many modules) need baketime if the bag was open.

02 On an ESP32 board

  • ESP32 module pin-1 vs the courtyard in CAD must match the tape orientation.
  • Crystals and RF cans are orientation-sensitive and hate a nozzle that crushes them.
  • Tall USB next to a low 0402 needs a place order that does not knock parts.

03 What usually fails

  • 180° module, USB backwards, diode flipped.
  • Wrong reel on a look-alike 0402 value.
  • No local fiducials on a fine-pitch island.

04 What we check

  • We generate a centroid from the same CAD that made Gerber, then spot-check pin-1 on ESP32, USB and DCDC.
  • MSL and bake are on the kit list, not an afterthought when the module tombstones.

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中文

PCB工艺 / 贴片

组装 · 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。

01 这一步做什么

  • 机器用坐标（XYR）和供料器。视觉看拼板上的基准点。
  • 细间距和 QFN/BGA 要有基准点和真正的封装中心，不是丝印中心。
  • 潮敏器件（很多模组）开袋要烘。

02 落到 ESP32 板上

  • ESP32 模组 1 脚要和编带方向、CAD 封装一致。
  • 晶振和射频罩怕被吸嘴压坏。
  • 高 USB 旁边矮 0402，贴装顺序不能撞件。

03 常见失败

  • 模组转 180°，USB 反了，二极管反了。
  • 0402 料带贴错阻值。
  • 细间距区域没有局部基准点。

04 我们查什么

  • 坐标从同一套 CAD 出，并抽查 ESP32、USB、DCDC 的 1 脚。
  • MSL 和烘料写在备料单上，不要等模组立碑再想。

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