www.nicomatic.com
METAL DOME ARRAY
Design Guidelines
This sheet will provide a guideline for designers who require domes and dome array products in elec-
tronic devices. The information below is proprietary and specic to NICOMATIC and its manufactu-
ring processes. Designers should consult the NICOMATIC engineering department early in the design
process to insure a compatible dome array that will yield the desired product functionality.
NICOMATIC PROCESS
:
*+/- 0.20mm for N6 domes /+/-0.15mm for N4 & N5 domes
Notes:
- Dome arrays that require tighter manufacturing tolerances are sometimes possible but
need to be communicated with the NICOMATIC engineering team early in the design cycle.
STANDARD PART SIZE
- Standard sheet dimensions are 150 mm (5.90“) long to 120 mm
(4.72”) wide. The sheet dimensions can be larger (eg. 10 mm) but will
not t the standard packaging. For greater length, dedicated MDA* and
control equipment will occur.
- The edges of all adjacent domes should be at least 1.00 mm (0.039")
from one another. With dedicated tubes, NICOMATIC can reach a mini-
mum distance of 0.5 mm (0.020 ") between metal dome edges.
- For P.A.S**. type arrays, the spacer hole should be 1.00 mm larger
than the dome's dimension.
- If an insulated barrier or double side adhesive is used, the hole in the
barrier around the domes should be 1.00 mm larger in diameter than
the dome size. Please consult us if a smaller hole size is needed.
- Up to 256 domes can be placed onto a sheet whatever the type (force,
plating & shape). Additional metal domes can be placed but this ope-
ration will require 2 times process control.
- Any shape of array as well as dierent types are allowed on the same
metal dome sheet.
* Multi-Dome Assembly - **Pre-assembled spacer
Feature description
Tolerance So tooling (P.A.S. & Kiss Cut)
- for prototypes & pre-series
Tolerance Hard tooling (P.A.S. & Kiss
Cut) – for series process control
1 - Tooling hole to hole ± 0.1mm (0.0038")
2 - Tooling hole feature ± 0.1mm (0.0038") ± 0.05mm (0.0020")
3 - Cut to cut ± 0.25mm (0.0098") ± 0.15mm (0.0059")
4 -Dome to tooling hole ± 0.25mm* (0.0098") ± 0.25mm*(0.0098")
5 - Tooling hole to position slot ± 0.25mm (0.0098") ± 0.25mm (0.0098")
6 - Part Edge Periphery & Slot
dimensions
± 1.00mm (0.039") ± 1.00mm (0.039")
0
0
2 - Ø ± 0.05 mm
3 - ± 0.15 mm
4 - ± 1 mm
4 - ± 1 mm
6 - ± 1 mm
5 - ± 0.25 mm
3 - ± 0.25 mm
3 - Ø ±
0.15 mm
4 - ± 0.25 mm
2- ± 0.25 mm
1 - Tooling hole to hole
± 0.1mm
Cut to cut
Cut to cut
The following guidelines are designed to be easily achievable by NICOMATIC’s current manufacturing
process for standard size dome arrays at the lowest possible product cost and 100 % controlled.
STANDARD MANUFACTURING TOLERANCES
Prototype
± 0.25mm (0.0098")
± 0.25mm (0.0098")
± 0.25mm (0.0098")
Pre-series
± 0.15mm (0.0059")
± 0.15mm (0.0059")
± 0.15mm (0.0059")
1
www.nicomatic.com
STANDARD MATERIALS
- NICOMATIC metal domes are formed from 301 stainless steel and
nickel plated as standard. Bare, silver or gold plating is also available
upon request. Multiple dome shapes and sizes are available in many
dierent trip forces and tactile ratios.
- Standard dome seal material (top layer or spacer) is 0.05 mm thick
PET with 0.02 mm acrylic adhesive. This is available in either clear or
white colour. Release liner thickness is 0.08 mm thick.
Other thicknesses are also available, please consult us for details but
be careful not to damage or strongly reduce the tactile feeling.
NICOMATIC has approved top layer thickness between 0.06 mm and
0.10 mm. For P.A.S. spacer it must be between 0.06 and 0.08 mm for 4,
5, 6 mm domes. The release liner should not be greater than 0.15 mm
otherwise the control machine may not work properly.
OTHER DESIGN CONSIDERATIONS
- Four holes of 4mm diameter at (0,0) , (0, 110), (140,0), (110, 140) are
required for the NICOMATIC dome placement process.
- NICOMATIC recommends an origin hole and a direction on each indi-
vidual array to dene precisely the position of each dome.
It is necessary for inspection.
- In standard, no marking is put on the array. Specic marking can be
printed at overcost on customer request.
- If polyester removal is required, arrays can touch each other. In other
more standard cases, a 1.50 mm space should be le between the ar-
rays on the sheet.
- Dome position and dome force reports can be provided upon request.
- Hermetically sealed domes require an air vent to function properly.
This can occur by either standard top side venting (kiss cuts), by a
through hole in the PCB board or by air tracks, which should be 1.00
mm wide and link at least 2 domes.
- All internal holes (Positioning, LED) should be a minimum of 1.20 mm
in diameter.
- In order to create a sealed switch, all dome edges should be a mini-
mum of 1.00 mm from the edge of the part or any other cut.
- ESD/EMI shielding can be added by printing the top surface of the
part with silver ink. The printing needs to be oset from the edges of
all cuts and dome vents by 1.00 mm.
- Recommendation: Activators should have a round shape (diameter
1.50 mm to 2.00 mm) or at shape with 1.50 mm diameter depending
on the metal dome type.
- Our hard tooling is generally used for high volume > 50k arrays.
Production capability of this tooling is standard 2 500 sheets per shi.
It requires high quality & in-house designed and assembled toolings
for placement and control.
- The so tooling is mainly used for prototypes or pre-series it allows
more exibility.
- NICOMATIC 4-legged square domes are required for single sided PCBs
and ex circuits that have a top-side track for the center dome switch
contact. Contact NICOMATIC engineering if your design requires this
type of PCB design.
- Automated assembly of metal dome arrays to ESD/EMI shieldings,
keypads, PCBs, ex circuits or EL lamps is possible.
Call your Key Account Manager for specic requirements.
PACKAGING & SHIPMENT
- All sheets parts are delivered in sealed boxes for standard sheet di-
mensions 120 mm x 150 mm. Each box is labeled with NICOMATIC and
customer part numbers. Other packagings are available (reel, indivi-
dual arrays...).
- Weight for a metal dome: ± 0.02gr
- Weight for a metal dome array (typical 20 domes array): ± 0.45gr
- Typical storage stability: 2 years stored at 21°C and 50% RH
- Service temperature range: -40°C to +105°C
FILE TRANSFER TO NICOMATIC
For dome arrays approval by our engineering department,
the following information is needed:
- Customer drawing mentioning all dimensions in .DXF or .DWG format
clearly showing top view and tolerances.
- Type of dome array selected: either top side venting (with kiss-cuts)
or with Pre-assembled spacer (P.A.S. extra layer).
- Type and part number of metal dome inside the array :
diameters 4 and 5mm circle, diameters 6, 8.4, 10 and 12.2mm square
(4-legged), DD type (Please always specify which Trip force, Rebound
force, Click ratio and Plating.)
- Type of polyester used: white, transparent or other material specied
by the customer.
Please use our online Dome array check-list formular to specify your
need (Availaible as attachment).
2