Imported from mszkowalik/KiCad-Lib (.claude/skills/kicad-conventions-library/SKILL.md). Install upstream with npx skills add mszkowalik/KiCad-Lib --skill kicad-conventions-library. Copyright stays with the author.

Library conventions

This is the house style for component data: manufacturer naming, description (ki_description) standardization, the Value field rule, and category placement. Read it before proposing any new component or editing an existing one's properties.

Scope: this document covers property values. Geometry conventions live in [[conventions-symbols]] and [[conventions-footprints]]; the step-by-step procedure and the validation rules a draft must satisfy are in [[add-component]]; what happens after approval is [[platform-workflow]]. A full standardization pass across every category was completed 2026-07-21 (308 components checked, 198 edit proposals drafted) — see the closing note at the end of this document.

1. Manufacturer names (Manufacturer 1)

Raw data from LCSC/JLC feeds is unreliable for casing: it is frequently ALL-CAPS (distributor-shout), inconsistently cased, or a bare/cryptic code. Never copy it verbatim into Manufacturer 1 — resolve it to the canonical form below.

Canonical form rule

Use the manufacturer's own official brand capitalization — normal Title Case for most legal/brand names, except where the company's own stylization is genuinely different. Do not "fix" a company's real stylization into Title Case.

Known deliberate exceptions to normal Title Case (verified against the company's own branding — keep EXACTLY as shown):

Lowercase brand exceptions:

• u-blox — lowercase u, hyphen, lowercase blox, even at sentence start; confirmed via the company's own site/Wikipedia. Do not write "Ublox" or "U-Blox".
• onsemi — ON Semiconductor officially rebranded to this lowercase trade name in 2021 (investor.onsemi.com, press coverage). Same exception class as u-blox. Do not write "Onsemi" or "ON Semiconductor".
• 8devices — UAB "8devices" (Lithuania); lowercase "d", confirmed via the company's own site footer copyright line ("© 2012-2026 UAB "8devices"") and its logo/header casing throughout 8devices.com. Do not write "8Devices" or "8 Devices".

All-caps brand exceptions (genuine manufacturer stylization, not distributor shout-casing):

• KEMET
• OSRAM
• KNSCHA
• TDK — Tokyo Denki Kagaku; all-caps is TDK Corporation's own brand/logo usage, not a spelled-out Title Case name. Distinct from TDK InvenSense below (a joint-venture brand).
• TDSEMIC — all-caps on the company's own datasheet letterhead logo and in the footer URL printed on every page of it (tdsemic.net). Same evidence class as the KEMET/OSRAM entries: the manufacturer's own material, not a distributor listing. No fuller company name was found on any primary source, so none is recorded here — do not expand the acronym on a guess.
• XR — Dongguan Xiangru Electronics Co., Ltd.; branded and listed everywhere simply as "XR", including its own LCSC brand page (titled literally "XR").
• YLPTEC — Zhongshan Yichuan Electronic Technology (中山市易川电子科技); all-caps on the company's own datasheet letterhead logo, in the WWW.YLPTEC.COM footer printed on every datasheet page, and silkscreened on the module body in its own outline drawings. Same evidence class as the KEMET/OSRAM entries: the manufacturer's own material, not a distributor listing. Do not Title-Case to "Ylptec".
• YXC — Shenzhen Yangxing Technology Co., Ltd.'s self-owned brand.
• XINGLIGHT — confirmed via the manufacturer's own site (xinglight.cn) and DigiKey's supplier page.
• TAKACHI — confirmed via the manufacturer's own site (takachi-enclosure.com), including its copyright line.
• OMRON — confirmed via Omron's own domains (ia.omron.com, omron.com) and a 2024 press release citing "OMRON" as a registered trademark. Do not use "Omron Electronics" (a distributor/subsidiary name seen in the raw feed).
• MEAN WELL — confirmed via the company's own brand-story pages (meanwell.com, meanwellusa.com, meanwell.eu); two words, both all-caps.
• DEGSON — confirmed via degson.com's own running body copy and footer copyright text.
• BHFUSE — Shenzhen BHFUSE Industrial Co., Ltd.; stylizes its own legal name all-caps, confirmed via LCSC's own blog post.
• XFCN — XFCN Connectors Co., Ltd.; confirmed via the company's own LCSC brand-page About text ("hereinafter referred to as 'XFCN'"). Resolves the skill's former open item.
• ISSI — Integrated Silicon Solution, Inc.'s own all-caps acronym; confirmed via issi.com and its own datasheet cover pages.
• HCTL — Shenzhen Huacan Tianlu Electronics Co., Ltd.; consistent all-caps acronym across the company's own LCSC brand page and product listings.
• RCH — Wenzhou RuiChuan Electronics Co., Ltd.; consistent all-caps brand code. (Confirmed via distributor listings, not a formal press kit — slightly lower certainty than the others in this list.)
• RESI — C&B Electronics (Shenzhen) Co., Ltd.'s precision-resistor brand; the company's own English site en.resistor.today prints "Brand: RESI" in body text and titles its series pages "Precision RESI Resistor". LCSC also lists the brand as "RESI" and sometimes as "Resistor Today" in URLs — use RESI. Same evidence class as the KEMET/OSRAM entries: the manufacturer's own material.
• SOFNG — sofng.com's own copyright notice ("SOFNG All Rights Reserved"). (Same lower-certainty caveat as RCH.)
• SCTF — sctfcrystal.com self-titles as "SCTF | Crystal Oscillator Manufacturer...". Resolves the skill's former open item.
• TOGNJING — consistent all-caps across LCSC and Chipmall with no fuller company name found anywhere. Lower confidence than the rest of this list — no manufacturer homepage was ever located; re-check if a better source turns up.

Other special stylizations (not plain Title Case, not all-caps, not lowercase):

• FIX&fasten — bold "FIX" + stylized "&" + lowercase cursive "fasten", per the manufacturer's own FIX-LEMB datasheet letterhead. Do not "correct" to the distributor's shout-case form FIX&FASTEN seen on TME/X-ON/FindIC.
• Worldsemi — only the leading W is capitalized (not "WorldSemi", not "WORLDSEMI", not "World Semi"). Confirmed via world-semi.com and LCSC's own brand-page heading.
• MaxLinear — internal capital on the L (not "Maxlinear"). Confirmed via lcsc_lookup matching the company's own brand spelling.
• G-Switch — Title Case with a hyphen; confirmed consistent across LCSC, HQonline, SemiKey, X-ON for the GT-TC/GT-USB product lines.

Parenthetical / expanded brand forms (distributor-catalog form that names the parent company in parentheses — use exactly as shown, including spacing/punctuation):

• MDD (Microdiode Semiconductor) — LCSC's own brand page is titled exactly this way.
• UNI-ROYAL(Uniroyal Elec) — no space before the parenthesis; matches LCSC's brand page and the part's own datasheet filename.
• WCH(Jiangsu Qin Heng) — no space before the parenthesis; consistent across the whole CH340 family on LCSC.
• UMW (Youtai Semiconductor Co., Ltd.) — space before the parenthesis; confirmed via umw-ic.com and multiple distributors.
• FH (Guangdong Fenghua Advanced Tech) — space before the parenthesis; applied to the 0402CG101J500NT thick-film chip resistor family.

Everything else defaults to normal Title Case / proper legal-name casing (e.g. STMicroelectronics, Texas Instruments, Espressif Systems, Analog Devices, Winbond, AMD/Xilinx, Hammond Manufacturing, Samsung Electro-Mechanics).

Canonical manufacturer table

(Raw/messy forms seen in feeds -> canonical value to use. Sorted alphabetically by canonical value.)

Open items — could not confidently resolve, do not guess

• TWGMC (seen on SS34) — still unresolved after a second research attempt. Only a weak, unquotable claim links it to "Taiwan Dijia Electronics Co., Ltd."; no authoritative primary source found. Ask the user or research further before normalizing components using this code.
• Milliohm (seen on HoYH0805-3/4W-50mR-1%, LCSC C42389461) — Shenzhen 毫欧电子, whose datasheet and whose own site (moolee.com.cn) name the company ONLY in Chinese: 深圳市毫欧电子有限公司 / 深圳市毫欧电子科技有限公司, brand mark 毫欧 / HoYH. No English brand form exists in any of the company's own material, so the KEMET/OSRAM test cannot be applied at all. Milliohm is LCSC's brand-page form and a literal reading of 毫欧, and is what the component carries — but it is distributor-sourced, same evidence class as TOGNJING. Recorded 2026-08-27. Re-check if a manufacturer-published English name turns up; the footprint vendor token would be Milliohm.
• TECH PUBLIC (seen on PESD5V0S1BA) — consistently ALL-CAPS across LCSC/JLCPCB/HQonline, possibly = Taizhou Electronics Co., Ltd., but no official company homepage was found to confirm the brand's own stylization (unlike the KEMET/OSRAM-class exceptions, which are anchored to the company's own material). Left as-is since it matches every distributor form seen, but do not add it to the exceptions list above as a confirmed all-caps brand yet.
• Kinghelm vs. Shenzhen Kinghelm Elec naming conflict — two different sessions used two different canonical forms for the same company (Shenzhen Kinghelm Electronics Co., Ltd. / kinghelm.net): the abbreviated Shenzhen Kinghelm Elec is used consistently on 4 existing Buttons/RF components, while a later Connectors-chunk session normalized a different component to bare Kinghelm, citing the company's own site. Both forms are recorded in the table above for traceability. Do not silently pick one and reconcile — surface this to the user/maintainer to decide the single house form, then normalize every affected component to match in one pass.

Procedure when you meet a new/unclear manufacturer name

1. Check this table first.
2. If not listed, check lcsc_lookup and/or a quick web search for the company's own stylization (their homepage, Wikipedia infobox, or press material) — do not just guess a "nicer-looking" casing.
3. Use that verified form in Manufacturer 1.
4. If it's a new company not yet in the table above, add it the next time you touch this skill (propose_skill_update), so future look-ups are instant instead of re-researched every time.
5. If several sibling components already use a manufacturer name inconsistently, standardize all of them to one form in the same edit pass (mirror whichever form is verified correct, don't just pick the majority).
6. If you discover the library already uses two different canonical forms for what looks like the same manufacturer, do not silently pick one — add both forms to Open items above and surface the conflict for a maintainer decision (see the Kinghelm example).

2. Descriptions (ki_description)

Never hand-type a free-text description copied from a supplier catalog blurb. Use a {Key}-based template so descriptions stay consistent, are generated from real filterable/searchable properties, and update automatically if a property changes.

Method for standardizing a category/sub-family

1. Pull every component currently in the category/sub-family (search_components by category, then get_component on each).
2. Identify the handful of properties that actually distinguish parts in that family (electrical + package), verifying real values against the datasheet where the existing description looks copy-pasted or suspect (e.g. confirm fixed vs. adjustable output before templating "Output Voltage").
3. Define one template string using only properties that exist (or that you add) on every sibling, e.g. "{Value} {Power} {Tolerance} {Footprint_Name}".
4. Add any missing discrete properties, then set ki_description to the template on every sibling in the same pass so the whole family reads uniformly.
5. Check component_where_used before editing any part that might be placed on a board, to make sure the edit is a safe property-only change.
6. If a sub-family only has one member, or its members are genuinely heterogeneous with no safe shared property set, do not force a template — leave it as clean, verified free text and record the decision + reason (see "Deliberately left as free text" below) so the next session doesn't re-litigate it.

Known property-key quirks (flagged, not fixed — needs maintainer sign-off)

Two base-symbol-wide property-naming issues were found this pass. Both are internally consistent across every affected sibling and don't cause wrong data — renaming a property key is a bigger, base-symbol-wide change than a description-templating pass, so they were left alone and are recorded here instead of being silently changed:

• Diodes / Zener sub-family uses the property key Zenner Voltage and comp_type=ZENNER (extra "n") on every BZT52Cxx/BZX84Cxx sibling. The Zener-family ki_description template intentionally keeps the same spelling to match the key name — this is a deliberate consistency choice, not an uncaught typo.
• Transistors / BJTs (BC817-40-7-F, BC847CLT1G, MMBT3904,215) use the property key Continuous Drain Current for what is actually collector current — a copy-paste leftover from the NMOS/PMOS base template. The values themselves are correct.

If a maintainer wants either renamed, do it as one dedicated base-symbol pass across every affected sibling at once, not piecemeal.

RESOLVED 2026-09-11 — VSWR, not V.S.W.R. RF carried both spellings for the same quantity: four on-board antennas on V.S.W.R (ACS0301U, BWGNSCNX9-9W2, GPS1003, KH5220-A36) and four cabled parts on VSWR (AEWW031, BW4GJWX195-13KJ, and the two RF pigtails). Two keys for one quantity means a {Key} template, a parametric filter or a future family standard silently reaches half the category. The house spelling is VSWR — the ordinary unpunctuated acronym, matching every other acronym key here. All four V.S.W.R parts were renamed in one pass; the category now reads one way.

This is also the worked example of when such a rename is cheap. A property key is NOT in NON_MATERIAL_KEYS, so renaming one blocks the verification and sign-off carry and the part comes back unreviewed. All four were unreviewed and unsigned, and no ki_description referenced the key, so the pass cost nothing. Check both of those before renaming a key on a signed part — on a verified one, the rename costs the verification.

Templates already standardized

Power ratings (Power) — one spelling per rating

Power is a filterable property and it fills the {Power} slot in every resistor template, so a rating spelled two ways splits the family: a BOM filter or a parametric search finds half the parts. One rating, one string.

1/16 W is always 63mW. Never 62.5mW, never 0.0625W.

Decided by Mateusz Kowalik on 2026-08-28, after RC0402FR-0749K9L was published as 62.5mW beside sixty 63mW siblings sitting on the same 0402 land. The three parts that carried the decimal form (RC0402FR-0749K9L, RT0402BRB071KL, RT0402BRD079K09L) were normalized to 63mW in the same pass, so the category now reads one way throughout.

This deliberately overrides the datasheet's own wording. Yageo's RC_L ordering example on p.2 spells the rating "RC0402 0.0625W", and the RT-series power table says 1/16 W; both mean 62.5 mW, and the house form rounds it. Do not "correct" a 63mW back to a datasheet-exact decimal — put the exact figure in the verification note, which is where the evidence belongs.

The general rule behind it: a fractional wattage is written as its value in whole milliwatts. Most ratings are already integers and raise no question — 1/20 W = 50mW, 1/10 W = 100mW, 1/8 W = 125mW, 1/4 W = 250mW, 3/4 W = 750mW, 1 W = 1W, 2 W = 2W. 1/16 W is the one that does not divide evenly, and 63mW is its decided form.

1/32 W (31.25 mW) is the other non-integer case. No library part carries it yet and no spelling has been decided — ask rather than inventing one.

Not every sub-63 mW figure is a rounded 1/16 W. PTFR0402B1K21N9 is correctly 60mW: the RESI PTFR datasheet's electrical table (p.2) rates the PTFR0402 at 0.03 W low / 0.06 W standard / 0.13 W high, which are the manufacturer's own power grades, not a rounding of 1/16 W. Confirm the rating in the datasheet before normalizing anything to 63mW — this rule fixes how 1/16 W is spelled, it is not a licence to round every nearby number up to it.

Deliberately left as free text (documented — don't re-litigate)

Remaining work (targeted follow-ups, not a from-scratch sweep)

Every category in the library has now been audited at least once (see the closing note). What's left is specific, not a fresh first pass:

1. Connectors terminal-block family — unify the ~36-member Phoenix-Contact-style family (plugs, bases, screw terminals, cage-clamp) onto one discrete {Pitch}-based template instead of the current three-way free-text convention. Needs both Connectors chunks reviewed together.
2. Buttons — backfill verified Length/Width/Height/Force properties across the whole category, then template.
3. Kinghelm manufacturer conflict — see Open items in §1; needs a maintainer decision before either form is normalized library-wide.
4. Individual ICs/LEDs/Timing_Components/Relays/TestPoints sub-families with only 1-2 siblings today (listed under "Deliberately left as free text" above) — revisit each once the library grows enough real siblings to template safely; don't force a template onto n=1.

3. The Value property — mandatory on every component

Value is the KiCad Value field: together with the reference designator it is the only part identity printed next to the symbol on a schematic sheet.

It must never be empty and must never be missing. The HTTP library (kicad_http.py) only emits a value field when the component actually has a Value property; when it is absent KiCad falls back to the base symbol's own name, so the sheet reads Conn_01x04 or TestPoint instead of the part. A missing Value is a defect, not a cosmetic gap.

Also never acceptable: ~, N/A, -, an unresolved {Template} placeholder, or a copy of ki_description (the description is a separate, longer field).

The rule

Value is the shortest string that identifies this part on a schematic sheet.

Decide in this order:

1. Is the component a member of a parametric family? — many library parts sharing one base symbol and differing only in a single primary rating (resistance, capacitance, inductance, Zener voltage, frequency…). If yes, Value = that rating, formatted per the table below. Nobody reads 0402WGF4701TCE off a schematic; they read 4K7.
2. Otherwise it is a specific purchased part → Value = Manufacturer Part Number 1, verbatim. Use the MPN, not the component name: component names are sanitized for KiCad (_ substituted for spaces and commas), so e.g. component MCV_1,5/_2-GF-3,5-LR gets Value = "MCV 1,5/ 2-GF-3,5-LR".
3. Exception to 2 — the MPN alone does not identify the part (it is a bare series number, or there is no MPN because the part is generic and not purchased) → Value = the component name. This covers test-point pads, mounting holes, generic solder pins, and manufacturers whose MPN is a bare code.

Per-category formats

Why the split: a parametric part's rating is what the reader needs and the MPN is noise; for everything else the MPN is the shortest unique identity, and inventing a nickname just creates drift between the schematic, the BOM and the supplier.

Documented deviations from "MPN verbatim" (don't re-litigate)

Placement in the property list

Insert Value first (position 0) on new components and when backfilling — this matches the majority of the library and KiCad's own field order (Reference, Value, Footprint, Datasheet, then custom fields). Value is stored with hide=true like every other property; the HTTP library router is what marks it visible on the sheet, so don't try to change hide to make it show.

Backfill status

A full-library Value audit was run 2026-07-25: 317 components checked, 68 had no Value property at all (36 Connectors, 25 ICs, 3 TestPoints, 2 LEDs, 2 Mechanical_7S). All 68 were drafted with the rule above; every other component already had a non-empty, on-rule Value. Known follow-ups left open deliberately:

• BLM18EG101TN1D (ferrite bead) still has Value = 68nH while its Impedance property reads 100Ω@100MHz. Per the table above a ferrite bead's Value should be the impedance — flagged for a maintainer decision rather than changed, because 68nH is also a real published spec for the part.
• Pin_0.7mm_Soldering_Pin carried duplicate empty Manufacturer 1 and Manufacturer Part Number 1 rows. The duplicates were dropped in its backfill draft. If duplicate keys show up elsewhere, drop them the same way — propose_component_edit rejects duplicate keys outright.

4. Category placement — check the source catalog's own category field

When importing or reassigning a component's category, don't infer it purely from part-number shape or which chunk you happened to be auditing — check LCSC's own catalog category field (via lcsc_lookup) or the datasheet before finalizing. Recurring miscategorization patterns found and fixed this pass:

• LEDs and photodiodes filed under ICs. Integrated-driver/addressable RGB LEDs (Worldsemi WS2812E-1313, WS2816C-1313 — LCSC category "LED Addressable, Specialty"), a UV LED emitter (M3535N1UVS8U12-365NM — LCSC "LED Emitters"), and a silicon PIN photodiode (VBPW34FAS — a 2-terminal diode per its own Vishay datasheet, not an IC) had all been imported into ICs. Moved the LEDs/emitter to LEDs and the photodiode to Diodes.
• Mechanical hardware filed under Connectors. SMD round nuts/standoffs (SMTSO2010CTJ, SMTSO2515CTJ — LCSC category "Board Spacers, Standoffs") are mounting hardware, not electrical connectors. Moved to Mechanical_7S.
• Before moving anything, check component_where_used to confirm the move is a safe property-only change on any board the part might already be placed on.

Last full-library Value audit: 2026-07-25 — 317 components checked, 68 backfilled as drafts (see §3).

Last full-library standardization pass: 2026-07-21 — every category audited at least once, 308 components checked, 198 component-level edit proposals drafted (all left as drafts pending user approval, nothing changed live). If you're about to start a "first pass" over a category, check the tables above first — it's very likely already been done.