This application note describes how to successfully attach surface mount LED indicator components to a printed circuit board. The application note describes the process of using automatic placement equipment to place LED indicator components on a printed circuit board and the process of using a reflow solder process to connect the components to the printed circuit board.
The note describes the three basic families of Agilent Technologies SMT LED indicator components – HLMx-xxxx sub‑miniature lamps, HSMx-xxxx chip and flip‑chip LEDs, and HSMx-Axxx-xxxxx PLCC LEDs – and provides guidelines for handling, packaging, and mounting on printed‑circuit boards. It includes details on standard EIA tape‑and‑reel packaging, moisture‑barrier envelopes, lead materials, and pad design considerations.
Procedures for automatic placement, solder paste application, convective IR reflow, Type‑2 board processing, and through‑the‑wave soldering are outlined, with recommended temperature profiles, moisture‑sensitivity handling, and process sequences to achieve high yield and avoid component damage.
| Moisture Barrier Envelope | Contains desiccant |
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Pad dimensions should not exceed the recommended size by more than 0.25 mm (0.010 in.) to ensure correct alignment and soldering.
The temperature difference must not exceed +100 °C (+180 °F) to avoid thermal shock to the SMT LED components.