Metal shrapnel (Shrapnel for short) (because its switch is like an upside-down pot, it is commonly called Guozi slice, or 'pot slice'), also metal dome in English, made of stainless steel, is an important part of the switch.
With the help of the conductivity, the metal shrapnel acts as a high-quality switch between the user and the product. At the same time, the stable resilience of the metal shrapnel (automatically reset after pressing) is leveraged.
The metal dome switches and snap dome are sure to be the switch button. If the various switches are separated from the Metal Domes, it loses its meaning, so it is said that the Metal Domes plays a key role in the switch, and it was later known as the metal dome switches and snap dome.
Application of a metal dome: used on button switches, membrane switches, tact keypads, self-locking switches, metal dome switches, and snap dome.
Function of metal dome switches: to power on and off, which can give the operator good tactile feedback.
Originally, there is no professional name called snap dome in the early days. And a snap dome is made of metal material. Because it is a dome, it can bounce upward and be concave downward (convex and concave). Its initial state is convex upward, and it will concave downward when the operator exerts a force, and then rebounds after the force is removed. This kind of elastic metal material is uniformly called metal dome or snap dome. Later, when metal dome switches were introduced into China, many people were used to calling them metal dome switches. Metal domes also referred to as metal snap domes or tactile metal domes
There are four main shapes of Metal domes: triangle, circle, ellipse, and cross, with 1, 4, and 5 contacts on the top. The stickers of Metal domes should be customized according to individual needs, do not use them randomly, and avoid affecting the quality of the products. It is very convenient to assemble the stickers on the pot, and it is enough to attach a full version. Of course, pay attention to the stability of the conductive parts of the pot and the circuit board.
Metal domes are mainly in the size of 4MM, 5MM, 6MM, 7MM, 8MM, and 9MM. With a strength of 100-600gf (the strength depends on the customer's product needs), triangular pots are widely used and involve all aspects of our modern life.
The size of the pot is different. The strength can be set to large or small. If special requirements are required, special materials can be used. The strength can reach about 3000gf. The triangle has three feet and a vertex. The legs of the triangular pan can be long and endless, these are determined by the needs of customers.
Metal domes are mainly used in circuit boards, tact switches, micro switches, key switches, pc boards, and other products. It has the characteristics of stable contact, good continuity, and excellent rebound feel. The triangular pan-shaped piece is an excellent accessory used in major electronic products.
About the pot pieces:
The pot pieces can be tinned, silvered, gold-plated, and other different surface treatments. Different treatments on the surface can produce different effects. For example, tin plating can solve the problem of heating without fading. In addition, gold plating and silver plating on the surface will increase the pot pieces Gloss has a certain resistance effect.
About the pan-shaped pieces:
The pan-shaped pieces are generally made by customers with drawings provided by us. The types of pan-shaped pieces most used by the guests are round pieces and oval-shaped pieces, also known as waist-shaped pieces and cross-shaped pieces. Triangular pan slices and rectangular pan slices have diameters from 3mm to 20mm, strength from 100gf to 600gf, and special strength pans can reach 6000gf.
The back of the pan-shaped piece can be dotted or not, the round pan-shaped piece is generally five contacts, and one contact, some special needs no contact. In order to facilitate assembly, the pot pieces are generally stuck together with PET, which not only facilitates assembly but also accurately positions.
About its different names:
Metal domes are also known as metal shrapnel. Its English name is meal Dome slices. Sometimes people will say membrane switches. The name of Metal domes is generally based on his purpose. The ones commonly used in industry are called The shrapnel, and used in mobile phones, the keyboard is called the potsticker, and the switch series is called the membrane switch. Single-layer potstickers are generally full-page stickers.
Advantages: agile operation, fast assembly, disadvantages: bad experience for customers, no dustproof function, easy to be invaded by dust, and cause contact problems. Therefore, the single-layer pot-shaped pieces are becoming smaller and smaller in the market. Only when the Tiebei sealed machine does not require the protection and operation of the pot-shaped pieces, the whole-plate stickers and single-layer structured pot-shaped pieces will be used. The advantages of Double-layer film potstickers are: dustproof, durable, good feel, etc.
Disadvantages: high cost, slow assembly, etc. Double-layer membranes are widely circulated in the market, and almost all electronic products use double-layer structure pots, such as gaming keyboards, medical equipment, and even as small as remote controls. The single-layer metal dome picture below: The application of Guozi films and Guozi film stickers are becoming more and more widespread, and currently involves all aspects of life, such as the induction cooker we use for cooking, TV, air conditioning remote control, mobile phone equipment, bank U shield, cash machine, medical equipment products, various A series of buttons, touch switches, and other products are used in the pot.
Metal dome is widely used. The metal dome is also the most important part to complete the work on the membrane switch. The main function of the metal dome is to contact and disconnect the power supply. Metal dome is generally made of SUS301 or 304 material. The life of the metal dome is generally over 100,000 times. The strength is determined by demand. Do not use it under too high temperature. Excessive temperature will seriously affect the service life of the metal dome.
The metal dome is used on the membrane switch to play a conductive role, conducting the two-pole contact of the membrane switch and rebounding by its own elastic force to complete the power-on and power-off functions. It is energized when the shrapnel is down and powered off when the shrapnel rebounds. Give the customer tactile feedback during the rebound process, with a certain feel (Note: proper operation, excessive back and forth movement may cause the switch to lose response).
There are many common causes of failure of shrapnel:
The operation is too frequent.
The pressure is too large, the stroke is too high.
The isolation layer is too thick.
The operation force is too small.
The effect of these reasons on the membrane switch is that if the shrapnel is forced too hard, the shrapnel cannot spring back, resulting in a continuous path, which means that the metal dome has been working.
The too-frequent operation causes the switch to malfunction and does not work for a short time. Excessive pressure will directly crush the shrapnel and keep working or not working. If it is too large, the metal dome may not be able to complete the work.
Therefore, the factors we need to consider when applying metal dome to the membrane switch are whether the metal dome can withstand the pressure of this product, whether the stroke is consistent with this product, and the isolation layer should not be too thick.
Metal domes are not without a fixed shape and size. They are a kind of custom-made products that can change the shape and size according to the needs of the product. The specifications and sizes of commonly used metal dome or snap dome are:
Round snap dome
Size: 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm. Round keys currently with these shapes are much used by customers.
Strength: 90gf, 100gf, 130gf, 160gf, 180gf, 200gf, 220gf, 250gf, 260gf, 280gf round keys. The most used strengths are divided into these types.
Appearance: there is one contact on the top, four contacts, and five contact buttons, and there are also no points and one contact on the top. The three-snap points are evenly distributed on the edge. The round metal domes are all the key shrapnels with the shortest stroke in the shape of the metal dome.
Triangle snap dome
Size: 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm. Triangle key shrapnels currently have more customers with these diameters.
Strength: 130gf, 160fg, 180gf, 250gf, 280gf, 320gf, 350gf, the pressure of the triangular pot is generally these types.
Appearance: the triangular snap dome has two kinds of feet and no feet. The triangular key springs with feet can be directly welded on the PCB board. There are two kinds of points, one is with one point The species is one point among the three surrounding points.
Cross-shaped snap dome
Size: 5mm, 6mm, 7mm, 8.4mm, 10mm, 12mm, 13mm, the cross-shaped snap dome customers use more than 7 diameters.
Strength: 130gf, 180gf, 220gf, 280gf, 350gf, 400gf.
Shape: there are no dots, there is one dot in the middle, four dots at the top, and four dots at five dots.
Oval pan and quadrilateral snap domes
The oval and quadrilateral rectangular square pan slices are used together because they have no significant difference in shape and size.
Size: 3mm, 3.5mm, 4mm, 4.5mm, and 5mm.
Strength: 100gf, 130gf, 140gf, 160gf, and 180gf are the most used by customers.
Shape: there are no dots, one dot, four dots, and five dots on the surface.
Notes: It is more common for triangular pans to have feet, and for round shapes, there are also buttons with feet. Relatively speaking, the round pan pieces have a shorter stroke, the cross-shaped pan pieces have a larger stroke, the ellipse has a smaller diameter and less force, and the triangle has a shape that can reach a higher level. It can reach 3000gf, and all the pots can be silver-plated or tin-plated. The life of pots of different shapes can be the same. The life of pots in China is generally between 100,000 and 700,000 times.
As a metal dome switch supplier, we can offer various dome switch solutions, especially for tactile membrane keyboard and PCB. If you need customized shrapnel, please contact us, as a membrane keypad manufacturer, we can also export customized metal dome layer according to customer needs.