Electronic enclosures
Shell design for boards and batteries.
Electronic enclosuresIndustry
Injection Molding for Consumer Electronics
In a device, the plastic is the part people hold, drop, and judge. It also has to let radio signals out, keep a battery door shut for years, and hide every screw. Those jobs pull the design in different directions.
Part by part
Where each molded part of a device usually goes wrong
Most device problems trace back to one of these parts, and most are settled in CAD.
| Part | What goes wrong | Decide before tooling |
|---|---|---|
| Top and bottom shell | Sink over screw posts, a visible parting line, gaps that change around the edge | Which faces are cosmetic, where the gate may leave a mark, how the halves locate |
| Battery door | The latch loosens, or the door rattles once the snap relaxes | Latch style, a resin that recovers after flexing, how many openings it must survive |
| Buttons and keypads | Mushy feel, keys that stick, legends that wear off | Travel and click source, legend method, clearance to the shell |
| Display bezel | Warp that lifts the glass or leaves an uneven reveal | Gate position, glass bonding area, flatness requirement |
| Internal carrier | Boards and batteries shift when the device is dropped | Locating features and a stiffer, often glass filled, resin that nobody sees |
Radio
Plastic where the antenna has to see out
Metal blocks signal. Plastic mostly does not, which is why so many metal devices still carry a molded window or band.
- Carbon black, metallic paint, and conductive fillers can detune an antenna, so the resin and finish over the antenna zone are chosen together
- A plastic band or cap molded against a metal body is a classic insert or overmold job
- Antenna teams usually want the plastic geometry frozen early, since small moves change tuning
- Where shielding is needed elsewhere in the same housing, it is kept away from the window
Heat and materials
Chargers get warm, and people notice
Most device shells are PC/ABS. The exceptions tell you something about the product.
PC/ABS is the default for handheld shells because it molds cleanly, takes texture and paint, and survives drops. Wall chargers and power adapters sit next to hot components for hours, so they usually move to flame rated polycarbonate or PC/ABS grades. Wearables and earbuds that touch skin all day raise a different question: how the surface feels and how it holds up to sweat and lotion.
A flame rating belongs to the resin grade and the finished product listing, not to the mold. If the product needs a listing, name the grade the lab expects in the RFQ, and keep it once testing starts.
RFQ notes
What to mark on the CAD for a device
These notes shorten the DFM back and forth more than anything else.
Cosmetic faces, and where a gate or ejector mark would be acceptable
The antenna zone and any finish restrictions over it
Which snaps are opened by users and which close once at assembly
Color and texture targets, with a physical sample if one exists
Secondary steps such as pad printing, laser marking, or heat set inserts
Keep reading
Related guides
The parts inside a device, and the resins most shells are made from.
Bezels
Frames that hold glass flat.
BezelsButtons
Feel, travel, and legends.
ButtonsLight pipes
Carrying an LED to the surface.
Light pipesEarbud housings
Small shells with tight fits.
Earbud housingsPC/ABS
The default device shell resin.
PC/ABSConsumer products
Cosmetics, color, and launch volume.
Consumer productsIndustries hub
Every sector page in one index.
Industries hubFAQ
Questions from device teams
Can the same tool run a shell in several colors?
Yes. Color is changed at the press, not in the steel. Each color is quoted as its own part, and color changes are planned so runs stay long enough to hold a consistent shade.
How are screws hidden on a device shell?
Usually with snaps along the edge and screws under a label, foot, or battery door. Where screws are needed, heat set or molded in inserts keep threads from wearing out when the device is opened for service.
Can a soft grip be molded onto the shell?
Yes. TPE overmolded onto a PC/ABS or polycarbonate shell is common for grips, bumpers, and seals. The two resins have to bond, so the pair is picked together.
Is there a minimum order for device parts?
No. There is no minimum order quantity, which helps with launches where the first build is uncertain.
Next step
Send the shell, the door, and the buttons together
Upload every molded part of the device so DFM can check how they fit each other, not just how each one molds. NetProto manufacturing is ISO 9001 certified.