{"id":459,"date":"2015-03-24T18:06:54","date_gmt":"2015-03-24T10:06:54","guid":{"rendered":"http:\/\/www.metal-domes.com\/blog\/?p=459"},"modified":"2015-03-24T18:11:14","modified_gmt":"2015-03-24T10:11:14","slug":"why-metal-dome-array-doesnt-work-with-normal-force","status":"publish","type":"post","link":"https:\/\/www.metal-domes.com\/blog\/2015\/03\/24\/why-metal-dome-array-doesnt-work-with-normal-force\/","title":{"rendered":"Why metal dome array doesn\u2019t work with normal force?"},"content":{"rendered":"
<\/div>

Recently we received a customer complaint, he said some metal domes arrays<\/a> couldn’t work with required (normal) force and need higher push force, and even more some metal domes<\/a> are locked and no response.<\/p>\n

The metal domes<\/a>\u00a0customer uses is S6F-160-D-Ni, mean F-leg, diameter 6mm, force 160gf, with a dimple in center and nickel plated. The normal force is 160gf before assemble, but it seemed force changed a lot after assemble on PCB, and need higher force.<\/p>\n

Before seeing customer’s products,\u00a0we also couldn’t find the root reason, we checked and tested our metal domes<\/a>\u00a0before assembly, it\u2019s no problem, but after saw customer\u2019s finished product, we understood why this issue happened, because customer\u2019s design housing design is not suitable with metal domes array<\/a>.<\/p>\n

\"customer's

customer’s original metal dome array<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

Firstly, we checked\u00a0customer\u2019s assembled unit, obviously we found that four legs of metal domes<\/a> are pressed and fixed by the front plate housing after assembly, so when people pressed the center of metal dome, the legs of metal dome<\/a> can’t be extended peripherally as its original design, that means the front plate stop metal dome<\/a>\u00a0becoming collapse, so you have to press metal dome use much higher force than the designed force (160gf for that metal dome) to force it become collapsed.<\/p>\n

\"metal<\/a>

metal dome with front plate<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

But in most of cased, people don\u2019t know that and still press metal dome<\/a>\u00a0use designed force (160gf) and then he will found out that metal dome<\/a>\u00a0will not work. And then he have to increase the force, then bigger force damage metal dome<\/a> original structure, and then will change the force, and in most of case means reducing the clicking feeling. That’s also why we say metal dome can’t be soldered. (See more how metal domes work<\/a>).<\/p>\n

Second, we measured the diameter of plunger\u00a0on front plate, it’s only 4mm, but the diameter of metal dome<\/a>\u00a0is 6mm, you can see, obviously front plate will\u00a0press the inner function ring metal dome<\/a>.<\/p>\n

\"plunger

plunger of front plate<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

Third, we measured the diameter of rubber keypad, it\u2019s 3mm, that\u2019s too large, the larger stress area is, the higher push force will be needed. For 6mm metal dome<\/a>, the recommend size is 1.5mm (25%-30%*diameter of metal dome<\/a>).<\/p>\n

Suggestions:<\/p>\n

\"metal

metal dome array assembly suggestiong<\/p><\/div>\n