Custom Dome Arrays
A brand new range of metal dome arrays have recently been developed and manufactured by Memcon specially designed for membrane switch/circuit manufacturers.
A brand new range of metal dome arrays have recently been developed and manufactured by Memcon specially designed for membrane switch/circuit manufacturers. Providing a low cost replacement for the tact type switch and other short travel switches, the dome array has traditionally been used to reduce production costs and speed up assembly times – as one large dome array is placed into the application as opposed to a number of individual domes. In addition to the obvious cost benefits, this form of placement also reduces the occurrence of placement errors and “double doming” thereby improving quality control while the consistency in production ensures uniformity in the feel of the different keys.
Dome arrays are an excellent way of enhancing the tactile feel of a rubber key mat and can be adhered directly to a PCB with an overlay to create a tactile switch effect. The arrays are each custom developed to individual requirements and specifications and designs can be as simple or as complicated as the customers’ application warrants – from one or two domes in a simple single layer on a polyester backing to large panels incorporating a number of domes in a designated pattern, to those requiring spacers and EMI shielding layers. Different sizes and types of domes can also be incorporated into the array design; round, oblong and triangle, with or without dimple, feet, and legs.
The single layer dome array is one of the most original styles with the domes placed on a single layer of polyester/mylar film with an adhesive layer. Holes or kiss cuts are formed around the dome to assist with the breathing of the dome, thereby aiding its tactile effect. An ideal low cost solution to stick directly onto the PCB.
The double layer dome array construction incorporates a spacer layer into the assembly with venting allowing the domes to breathe included into the layer if necessary. Various materials and thicknesses can be utilised for the spacer material.
The EMI single/double layer dome array is of similar construction to the two above but includes an additional printed layer of silver or carbon paste to provide EMI/RFI shielding to the top of the PET film.
Finally the double layer with rubber adhesive utilises many of the construction options already given, but an additional layer of rubber glue can be added making it ideal for use with rubber keypads providing enhanced adhesion characteristics.
Clearly with each array custom designed, a dimensioned drawing with construction requirements, dome sizes and parameters with annual quantities required are needed before an accurate costing can be provided. A rough budgetary price can however be given from hand sketches if necessary.
Phil Heft – pheft@Hotmail.com ; PEMS Specialist