If you’re new to specifying custom cable assemblies, reading a cable assembly drawing (or writing one for your supplier) can feel unfamiliar at first. Here’s a quick guide to the key elements you’ll typically see.
Title Block
Like any engineering drawing, the title block identifies the part number, revision, drawn-by/approved-by information, and date. Always check the revision level matches what you expect — cable drawings go through revisions frequently as connector selections or lengths are finalized.
Connector Call-Outs
Each end of the cable will reference a specific connector part number, usually from the manufacturer’s catalog (e.g., “I-PEX 20455-030E-99” or “Hirose DF56-30P-0.3SD”). This tells you exactly which connector variant is used — pitch, pin count, and mounting style are all encoded in these part numbers, so it’s worth confirming the full part number rather than just the series name.
JAE FI-X30HL Hirose FI-S20S LVDS Cable Assembly
Wire/Pin Table
For multi-conductor cables, a wire table maps each pin on one connector to the corresponding pin on the other end, along with wire color or shield assignment. This is critical to check carefully — an incorrect pin mapping is one of the most common sources of assembly errors.
Dimensional Callouts
Overall cable length is usually specified with a tolerance (e.g., “150mm ±2mm”). Pay attention to whether the dimension is measured connector-to-connector or includes strain relief/overmolding, since this affects how the length is measured during QC.
AWG and Cable Construction Notes
The drawing should specify wire gauge (AWG), number of conductors, shielding type (if any), and jacket material. If these aren’t explicitly called out, it’s worth confirming with your supplier before production to avoid assumptions.
Testing and Inspection Notes
Some drawings include a notes section specifying required testing (continuity, impedance, hi-pot) or inspection criteria (visual standards, pull-test requirements). If your application has specific testing needs, make sure these are documented on the drawing itself, not just communicated verbally — this becomes the reference document for quality control.
Revision History Table
Most drawings include a revision table logging changes over time. When working with a supplier, always confirm which revision is currently being quoted or produced, especially if the design has gone through multiple iterations.
If You Don’t Have a Formal Drawing Yet
Many projects start without a formal engineering drawing — a rough sketch with dimensions, connector part numbers, and a wire table is often enough for a manufacturer to quote and produce a prototype. A formal drawing can be developed collaboratively once the design is validated.
If you have a sketch or partial specification and aren’t sure it’s complete enough to quote, send it over — we can identify what’s missing before you finalize the drawing.