Call the feature a PCB guide groove when a channel receives the edge of a circuit board. Card guide or board guide describes its function; molded groove describes its geometry and manufacturing method. A projecting strip is a rib, even when two ribs form a guide channel between them. On a drawing, combine the functional name with a section view and dimensions. That communicates more than choosing one supposedly universal term.
Choose the name that describes the feature
Several names can describe the same feature without being interchangeable. Use the functional name first, then describe how the feature is formed.
| Term | What it describes | What the drawing still needs |
|---|---|---|
| Card guide or board guide | A feature that locates or guides a board edge | Integral or separate construction, board orientation, fit and retention |
| PCB guide groove | A channel intended to receive a circuit board edge | Channel width, engagement depth, length and location |
| Molded groove | A recessed channel formed during molding | Its purpose, cross-section and mating-part dimensions |
| Mounting groove | A channel used to locate or support something | Identification of the supported part and required movement |
| Rib | A projecting strip of material | Whether it reinforces a wall, supports a board or forms one side of a channel |
| Gusset | A web that braces adjoining surfaces | Its structural purpose and clearance to nearby components |
“Integral PCB guide channels formed between molded ribs” is a useful description when that matches the geometry. “Separate board guides attached to the side walls” describes a different construction with a similar function.
Do not call every internal rib a card guide. A rib may stiffen the wall without providing a usable board mounting position. The broader PCB enclosure terminology article covers other internal features you may need to identify.
Show what touches the board
A section view should distinguish the channel opening from the material surrounding it. Dimensioning the ribs alone can leave the actual board clearance undefined.
Identify these contact surfaces:
- Channel flanks: the surfaces beside the board faces that control thickness clearance.
- Channel floor: the deepest surface that limits how far the board edge enters.
- Entry lead-in: the opening geometry that helps the board enter without catching.
- End stop: the feature that limits travel along the insertion direction.
A guide channel can constrain sideways motion without preventing withdrawal. It can also allow excessive movement along its length unless a separate stop or retainer exists.
State whether the PCB slides through an open end, drops into position before closure, or fits between assembled enclosure halves. Those arrangements need different access and retention details.
If the board rests on bosses and the grooves only limit lateral movement, say so explicitly. Do not imply that the grooves carry the board load. The PCB mounting boss screw article addresses the separate fastening interface when bosses provide the primary support.
Dimension the channel from defined references
Locate the channel from drawing datums, not from an unspecified outside edge. An internal base surface and two perpendicular locating surfaces can provide useful references.
Define the board plane first. Then show the insertion direction and identify which board edges engage the channels.
The drawing should control:
- Finished PCB thickness, including its permitted variation at the guided edges.
- Channel width across the board thickness.
- Channel engagement depth into each wall or guide.
- Distance between opposing channel floors.
- Channel center-plane position relative to the datums.
- Usable guide length and stop position.
- Entry lead-in and any corner radii affecting insertion.
- Component, solder-joint and connector clearances along the complete insertion path.
For opposing channels, board width and channel-floor spacing form a separate fit problem from board thickness. A channel may accept the board thickness but still pinch an oversized board between its floors.
Too much floor-to-floor spacing creates the opposite problem. The board can shift sideways until one edge loses adequate engagement.
Check both limits before releasing the drawing. Use the PCB enclosure tolerance stack article for the full dimensional stack rather than assigning an arbitrary clearance to each feature.
Use a drawing note that states the intended fit
A useful note names the feature, identifies the mating board and states how assembly should work. It should not replace the dimensioned section view.
The following is a filled-in example for a hypothetical enclosure with a removable front access cover. These are illustrative design dimensions, not catalog specifications or universal fit recommendations.
The associated drawing must still dimension channel depth, opposing floor spacing, guide length and the rear stop. It must also identify the front retainer and its attachment.
Do not copy these dimensions into a different enclosure without checking its board, assembly route and manufacturing capability. If the geometry changes along the guide, show that variation in sections or detailed views.
Check the tightest and loosest fits
Nominal dimensions cannot establish whether the board will slide into place. Compare the smallest permitted channel with the thickest permitted board.
For the example above, using the inch dimensions as controlling values:
- Minimum channel width: 0.079 − 0.004 = 0.075 in [1.91 mm].
- Maximum board thickness: 0.063 + 0.006 = 0.069 in [1.75 mm].
- Minimum total thickness clearance: 0.075 − 0.069 = 0.006 in [0.15 mm].
That clearance is the total gap across both board faces, not the clearance on each face.
At the other limit, the largest channel is 0.083 in [2.11 mm]. The thinnest board is 0.057 in [1.45 mm]. Their difference is 0.026 in [0.66 mm], which may permit noticeable movement.
These calculations establish dimensional limits only. They do not prove acceptable vibration performance, insertion force or connector alignment.
Use finished-board dimensions at the actual contact edges. Coatings, edge irregularities, bow and twist can affect fit. A nominal laminate thickness alone may not describe the finished interface adequately.
Also check the board envelope during insertion, not just after seating. A component can clear the enclosure in its final position but strike a rib while entering. Resolve that sequence before fixing the layout, as described in choosing the enclosure before board layout.
Verify fit without assuming other performance
The words “card guide” do not establish a tested load capacity, vibration resistance or environmental seal. Neither does a successful trial insertion.
Agree on the checks needed for the intended assembly:
- Confirm channel dimensions at the entrance, middle and far end.
- Check alignment between opposing channels.
- Assemble boards representing the relevant dimensional limits.
- Verify insertion and removal without forced bending or damaged board edges.
- Confirm the stop and retainer work without loading delicate connectors.
- Inspect component clearance throughout insertion and after closure.
Where vibration or shock matters, specify appropriate assembly testing separately. A sliding fit is not evidence that the PCB will remain secure under those conditions.
Likewise, internal guide geometry does not establish enclosure sealing performance. Keep guides, stops and retainers clear of gasket lands and closure hardware. If a guide continues into the closure area, review that interface separately using the tongue-and-groove gasket design article.
For molded parts, ask the fabricator to confirm achievable geometry and tolerances. Draft, radii and process variation can change the usable channel section. Preserve the functional clearance while resolving those manufacturing details; this article does not prescribe molding-tool dimensions.
Send the geometry with the quote request
Send a dimensioned enclosure drawing, a board outline and a section through the guide interface. Include the board thickness limits and component keepout zones along both guided edges.
Identify whether you need an integral molded feature, a machined channel or a separately attached guide. Do not assume those constructions are equivalent in assembly, retention or manufacturing effort.
Include the insertion direction, service access, stop arrangement and retention method. State which dimensions are functionally critical and which surfaces serve as datums.
We offer custom enclosures with customer-defined dimensions and cutouts. For polycarbonate and fiberglass, the available construction uses standard molded sizes cut to your layout. Do not assume a quote includes a newly molded body with relocated integral guides.
Describe the required board position first, then have the proposed construction confirmed before drawing approval. A clear functional name, a section view and a checked fit stack give the fabricator an actionable requirement.
Enclosures for this job
Catalog sizes that suit the job this article answers, picked from its subject; open one for its full specifications.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 20 × 16 × 8 in | 304 stainless | 20 x 16 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Are card guides and molded grooves the same thing?
Card guide describes the function of locating or guiding a board. Molded groove describes a channel formed during molding. A molded groove can function as a card guide, but a card guide can also be a separate attached component. State both function and construction when requesting fabrication.
Should PCB guide grooves be called ribs?
A rib is a projecting strip of material. A groove is the channel beside or between projecting features. Two ribs can form a PCB guide channel. If the ribs only reinforce the enclosure wall, calling them board guides could imply a mounting function they do not provide.
How much clearance should a PCB guide groove have?
There is no universal clearance suitable for every board and enclosure. Compare minimum channel width with maximum finished-board thickness, then check the loosest fit as well. Include board variation, channel geometry, insertion access and retention requirements before choosing the final dimensions.
Do guide grooves retain a PCB without screws?
Not necessarily. Channels usually guide and locate board edges, but they may still allow withdrawal or movement along the insertion direction. Define an end stop and a suitable retainer when needed. Verify the complete assembly against its service loads rather than relying on friction.
What should an enclosure drawing show for PCB guide grooves?
Send a dimensioned section through the channel, its location from defined datums, and the finished-board thickness limits. Add the board outline, insertion direction, edge keepouts, opposing-channel spacing, stop position and retention method. Identify whether the guide must be integral or may be separately attached.
