Are half-etched depth features specified on custom metal etching drawings | INNOETCH

Half-etched depth features on custom metal etching drawings should be specified as measurable, direction-specific recess features rather than vague shaded areas. For photochemical etching, a usable drawing must identify the etched surface, define target depth or remaining material thickness, locate the feature relative to datums, separate depth and planar tolerances, and state the inspection basis. This is especially important for thin stainless steel, copper, nickel, molybdenum, and aluminum parts where recesses control bending, step height, sealing, contact behavior, marking depth, or fluid geometry.

Start with etch direction and reference surface, not just a hatch pattern

Many drawing errors begin when a half-etch area is marked visually but the side of material removal is not defined. In precision metal etching, the same recess shape etched from the A-side instead of the B-side can change assembly orientation, bend direction, step contact, logo appearance, or channel function.

Functional orientation should be stated directly when it matters. A bend groove, hinge line, shim step, encoder track recess, logo cavity, electrical contact step, or fluid channel should show which face mates, bends, seals, or contacts in final assembly. If the part has no obvious top or bottom in the flat state, add a note such as “depth measured from assembly reference side” instead of relying on file layer names that may not carry through to production.

Define depth as a numerical value tied to material thickness

Chemical etching removes material from exposed areas, but actual recess response is influenced by alloy, temper, starting thickness, surface condition, and feature layout. A note that works for one stainless steel temper may not transfer directly to copper or aluminum, and the same etch depth on different base thicknesses leaves different remaining material.

For functional features, remaining material thickness is often the more useful specification because it relates directly to stiffness, bend behavior, electrical path, sealing compression, or step clearance. If etch depth is called out instead, the nominal sheet thickness must appear on the same drawing or specification sheet. For example, a note may define “0.05 mm recess from top surface” or “remaining thickness 0.08 mm after etching from bottom side,” but not both in a way that conflicts.

Drawing field	What to specify	Why it matters
Reference side	A-side, B-side, or assembly face used for measurement	Prevents recesses from being produced on the wrong surface
Depth basis	Target etch depth or target remaining thickness	Gives production and inspection one measurable target
Nominal material	Alloy, temper if relevant, and nominal sheet thickness	Supports correct etching parameters and depth review
Feature function	Bend line, logo, step, channel, cavity, contact area, or decorative mark	Helps teams prioritize depth control, edge profile, and appearance
Inspection basis	Micrometer, thickness gauge, optical check, cross-section approval, or visual comparison	Reduces disputes over whether a recess meets requirement

Separate planar, depth, and profile requirements before sample release

Half-etched features are three-dimensional, so one general tolerance block is usually not enough. At minimum, the drawing should distinguish the planar size of the recess, its location from datums, and its depth or remaining-thickness tolerance. A recess can be correctly located but too deep, causing weakening or over-bending; it can also meet depth but be shifted out of position, causing assembly failure.

Photochemical etching produces burr-free edges and fine etched structures, but half-etched sidewalls are not perfectly vertical. The transition from the unetched surface to the recess floor has a process-related profile. If the application requires a sharp bottom corner, unusually flat floor, specific wall slope, controlled edge break, or uniform surface appearance inside the recess, mark those conditions as critical and review them before tooling release. Noncritical decorative marks can usually rely on visual comparison, while functional steps, channels, and bend lines need measurable acceptance criteria.

Use drawing layers, views, and notes that survive translation into production

When through-etched openings, full-thickness lands, and half-etched areas appear on the same component, each feature type should be visually distinguishable. A dedicated hatch, color, or CAD layer for each half-etch side helps during artwork preparation, but visual marking alone is not sufficient. Add section views for any recess that could be interpreted from more than one direction, and place depth notes close to the feature rather than buried in general text.

Certain feature types need extra notation. Half-etched bend lines should indicate bend direction and whether the recess is on the inside or outside of the bend. Half-etched channels should state whether depth consistency affects flow or sealing. Half-etched steps in precision shims or mechanical parts should identify the mating surface. For encoder discs, lead frames, speaker grilles, filter mesh, and other components that combine through holes and recessed areas, datum structure and feature priority should be clear enough that inspection does not depend on verbal explanation.

Samples can help communicate intended contrast, feel, or bend behavior, but they should not replace dimensional requirements. If a customer sends a sample without a complete drawing, Innoetch can support engineering review to identify feature locations and evaluate depth, but formal production should still proceed from approved drawing data. Innoetch provides custom metal etching solutions based on customer drawings, samples, materials, dimensions, and application requirements, with support for prototype development, design optimization, precision manufacturing, process control, quality management, and stable mass production. For quotation and project review, customers can send drawings, material specifications, dimensions, tolerances, quantity, and application requirements to nico@innoetch.com.

Check inspection and approval logic before requesting a quote

Depth features create avoidable rework when the drawing does not say how conformance will be judged. Before sample approval, confirm whether recess depth will be checked with a micrometer or thickness gauge over the feature, whether position will be verified optically, whether cross-section checks are required during engineering approval, and which dimensions must appear on first-article reports. If some half-etched areas are cosmetic and others are functional, label them accordingly so tolerance and inspection effort match actual part risk.

A practical drawing review before release includes the following items。

• Etched side or assembly reference side is explicitly marked.
• Depth is stated as a numerical etch depth or remaining thickness, not as a vague percentage.
• Material alloy, nominal thickness, and relevant temper or surface condition are included.
• Half-etch areas are separated from through-etched features by layer, hatch, or view.
• Section views are added where depth direction could be misread.
• Depth, size, location, and any critical profile requirements are toleranced separately.
• Inspection method and reportable dimensions are identified for critical features.

This preparation helps engineering teams review manufacturability earlier, gives clearer direction for photochemical etching tooling, and makes sample approval a more reliable step toward repeatable production.

Frequently Asked Questions

Should half-etch depth be specified as depth from the surface or remaining material thickness?

Either can work, but remaining material thickness is usually preferred for functional features such as bend lines, shim steps, contact springs, and sealing surfaces because it directly controls mechanical or assembly performance. If depth from the surface is used, nominal sheet thickness must also be clearly stated.

Why is marking the etched side more important than the hatch pattern?

A hatch shows where a recess exists, but it does not tell production which face to etch from. Wrong-side etching can make a part visually similar while making it nonfunctional for bending, assembly, marking readability, or fluid control.

Can a reference sample replace a depth dimension on the drawing?

No. A sample is useful for showing appearance, contrast, feel, or bend behavior, but production and inspection need measurable dimensions. Samples support communication, while approved drawings define acceptance.

Do different metals require different half-etch drawing notes?

Yes. Stainless steel, copper, nickel, molybdenum, and aluminum each etch differently, and depth response can also change with temper, thickness, and surface condition. The drawing should always state the intended material and nominal thickness so depth requirements can be reviewed against process behavior. For project-specific review, customers can provide drawings, samples, material specifications, dimensions, tolerances, quantity, application conditions and delivery requirements to Innoetch.