Libraries and Parts in EasyEDA Pro: LCSC, JLCPCB Parts, and Custom Footprints

The EasyEDA Pro Library System

Imagine you are laying out a board in EasyEDA Pro and want to drop a resistor or a microcontroller onto the schematic. This is where the library begins. Every real component in EasyEDA is a bundle of three things: the symbol you see on the schematic, the footprint printed onto the PCB, and a 3D model for preview. The big advantage is that EasyEDA Pro is wired directly into the huge LCSC catalog and into JLCPCB's assembly service, so you do not just find a part — you see its stock, its price, and whether the factory can solder it onto your board.

The library system has four layers, and you should understand how they relate:

• System Libraries: generic ready-made parts (resistors, capacitors, standard connectors) shipped with the tool — handy for quick mock-ups but often without a real part number.
• The LCSC Catalog: the actual component distributor — millions of parts with an LCSC number and a manufacturer part number, plus live stock and pricing.
• JLCPCB Assembled Parts: a subset of LCSC the factory can machine-solder onto your board under the SMT service.
• Personal Library: the custom symbols and footprints you create and save for future projects.

Golden rule: use a real LCSC part with a genuine part number whenever possible instead of a generic system symbol, so your bill of materials (BOM) comes out order-ready with no manual fix-up.

The LCSC Catalog and JLCPCB Basic vs Extended Parts

The moment you plan to have JLCPCB assemble your board, the part's classification becomes a direct cost driver. JLCPCB splits JLCPCB Basic parts and Extended parts by whether they are pre-loaded on the assembly line or need a feeder mounted by hand.

The key idea is that the fee is charged per unique BOM line (per feeder loaded), not per individual component. If you place one Extended part and repeat it 50 times across 20 boards, you still pay the fee only once.

We verified the current fee model: on Economic PCBA, Basic parts are free to set up, an Extended part costs about $3 per BOM line, and "Preferred Extended" parts are exempt from the feeder-loading fee. On Standard PCBA there is no Basic/Extended distinction and every part carries about a $1.50 loading fee. Figures are approximate and the factory may update them.

The practical lesson: when picking a resistor or capacitor, look for the Basic alternative with the same value and package. That single choice can meaningfully cut SMT assembly cost on a board with dozens of parts.

Searching and Selecting Components

The search panel in EasyEDA Pro is your gateway to the catalog. Search by manufacturer part number, by LCSC number, or by specification (e.g. 10kΩ 0402 1%). For each result, read these fields before dropping the part onto the schematic:

1. Stock and price: avoid parts with zero or very low stock if you intend to order quantity.
2. Assembly class: is it Basic or Extended? This sets the cost, as we saw above.
3. "Assembled by JLCPCB" filter: enable it to see only parts the factory can solder, so you do not later discover your part is "purchase only."
4. Package and footprint: confirm the package (e.g. LQFP-48 or 0805) matches what your design actually carries.

Tip: fix the package first, then the value. Many board errors come from picking a part with the right value but a package that does not match the footprint on the board.

Read the full part panel — manufacturer number, LCSC number, datasheet link, and the attached symbol and footprint — before clicking "Place."

Creating a Custom Symbol

Sometimes the catalog has no symbol for a rare part or a new module, so you turn to the symbol editor in EasyEDA Pro to build the symbol yourself. The symbol is a logical representation of the part on the schematic — its physical shape does not matter, but the accuracy of its pins does.

When building a custom symbol:

• Draw the symbol body (usually a rectangle), then add pins one by one.
• Give each pin a name (e.g. VCC, GND, SDA) and a number that exactly matches the pin number in the datasheet.
• Arrange pins logically (inputs left, outputs right, power top, ground bottom) for readability, not by physical order.
• Set an appropriate designator such as U? for an IC or J? for a connector.

The most common mistake is a pin number in the symbol that does not match a pad number in the footprint. That number-for-number match is exactly what links the schematic to the board during routing.

Creating a Custom Footprint

The footprint is the actual copper land pattern on the board: the pads, the silkscreen, and the courtyard. You build it in the footprint editor, and every dimension comes from the mechanical drawing in the datasheet, not from guesswork.

Follow the IPC-7351 standard for footprint naming and dimensions. The standard defines three pad density levels:

When drawing the footprint:

1. Pads: take pad size and pitch from the dimension table in the datasheet and apply them precisely (e.g. 0.5mm pitch on an LQFP).
2. Courtyard: the clearance outline around the body that defines the mechanical space needed for assembly and rework.
3. Silkscreen: draw the body outline outside the pads; never place it over exposed copper.
4. Polarity mark: add a dot or chamfer pointing to pin 1 or cathode K — vital to prevent reversed placement.

Always verify the footprint against the mechanical drawing, then print it 1:1 on paper and set the real part on top to confirm the match before sending the board out.

3D Models and Importing

After the symbol and footprint, the component is completed by a 3D model that lets you preview the assembled board and check collisions with the enclosure or lid. In EasyEDA Pro you attach a model (in a format such as STEP or WRL) and adjust its offset and rotation so it sits exactly over the pads.

Practical points for importing:

• Model alignment: adjust the axis offsets and Z height until the part's legs rest on the board surface, not inside or above it.
• Import from the datasheet: many manufacturers publish a STEP file for the part; use it instead of modelling by hand.
• Importing footprints and symbols: you can import footprints or symbols from other tools or standard libraries in compatible formats, verifying them after import.

Never trust an imported 3D model as proof that the electrical footprint is correct — the model is for preview and collision; electrical accuracy comes from the footprint and the datasheet.

Library Best Practices

A trusted library is the designer's capital; a single footprint error can turn an entire batch of boards into scrap. Adopt these habits:

1. Always verify the footprint against the datasheet before the first order — pads, pitch, polarity mark.
2. Keep a verified personal library: move every part you have used successfully into your own library after physically verifying it.
3. Version control: keep your projects and libraries under version control to track any change to a symbol or footprint.
4. Clear naming conventions: name footprints per IPC-7351 (e.g. family + dimensions), not with random names, so any engineer after you understands them.
5. Prefer Basic parts when equivalent to lower assembly cost from the selection stage onward.

Summary

The EasyEDA Pro library system unites system libraries, the LCSC catalog, JLCPCB assembled parts, and your personal library into one ecosystem. The biggest cost decision you make is preferring free-to-set-up JLCPCB Basic parts over Extended parts, which cost about $3 per BOM line on the Economic service. When a part is missing from the catalog, you build the symbol in the symbol editor and the footprint in the footprint editor per IPC-7351, taking dimensions from the datasheet, then attach a 3D model and verify everything.

Next step: now that your design is ready and its components are verified, we move on to generating production files and ordering from JLCPCB.