Factors of mould water mark

What are the causes of water mark and how to improve it? For example, U-shaped parts

Water mark is also called water line, which is the melting line caused by the combination of two strands of plastic injection flow.

The reasons are: the nozzle design position is not correct or the nozzle design is not good. Poor die exhaust, etc

During injection molding, the mold temperature is too low, the material temperature is too low, and the pressure is too small.

improve:

1. In the structure, the bone position is added at the place where the water line is easy to be generated. The short side of the U-shaped part should be designed to be consistent with the flow direction of the nozzle.
2. Improve the nozzle.
3. Improve beer and plastic.

Please list the operation process of mobile phone assembly

Mobile phone assembly process:

The auxiliary material is usually beer plastic factory first installed on the rubber shell, PCB is generally a whole board.

PCB to a shell: button assembly on case a – PCB board – Case B (screw) – battery cover – Test – package

PCB to B shell: fix the PCB on the B shell and limit the position – install the button on the upper limit of the a-shell – screw AB shell – install the battery cover – Test – package

Please draw the size chain of the whole mobile phone

Take the straight plate machine as an example, there is no decoration on the surface, and the thickness is based on the battery: the figure will not be drawn, but the thickness distribution will be discussed. A shell glue thickness 1.0 + LCD foam 0.30 + PCB board thickness (whole board, not to mention the thickness) + battery and battery cover clearance 0.15 + battery cover thickness 1.0

P + R keyboard matching profile

Take P + R + steel plate button as an example: the figure will not be drawn. Let’s talk about the thickness distribution.

The distance between dome sheet and conductive base is 0.05 + the height of conductive base is 0.30 + the thickness of silica gel body is 0.30 + the thickness of steel sheet is 0.20 + the distance between steel sheet and a shell is 0.05 + the adhesive thickness of a shell is 1.0 + the key cap is generally 0.50 higher than the surface of a shell

What should be paid attention to in the design and assembly of steel keys

Attention should be paid to the design of steel keys

1. The steel sheet should not be too thick, about 0.20, or the handle is too poor.
2. The steel sheet cannot transmit light, and the light can only pass through silica gel.
3. The steel sheet is required to be positioned, and the steel sheet is fixed on the a shell on the long bending wall.
4. The steel sheet shall be grounded.

What should be paid attention to in the design and assembly of PC keys

Attention should be paid to the design of PC key:

1. The PC chip should not be too thick, about 0.40, or it will feel too bad. It can’t be too thin, or it’s very soft, causing poor hand feeling.
2. The light transmission of PC is not limited, and radium carving can be done at the light transmission place.
3. If the surface of PC chip is to be cut, the slot width shall not be less than 0.80, and the sharp corner shall be rounded (r0.30).
4. The assembly is generally connected with PCB by pasting double-sided adhesive tape on the back of silica gel, or long positioning column on a shell, and positioning hole is opened on silica gel to limit and assemble on a shell.

What should be paid attention to in the design and assembly of PMMA keys;

The design requirement is the same as that of PC. Generally, the surface of PMMA sheet should be hardened.

What should be paid attention to in the design of metal shell

When the metal shell is disassembled, it is generally 0.05mm lower than the large surface and 0.05mm lower in the Z direction.

Metal requires grounding, grounding generally with conductive foam, conductive cloth, spring, etc.

When the metal parts are buckled, the amount of fastening should not be too large, generally about 0.30.

When screw holes are made on metal parts, bottom holes shall be made first and then mechanical tapping shall be carried out.

The influence of process selection on ESD test?

Generally speaking, if there are hardware on the surface, poor grounding will affect ESD test.

If there are electroplated decorative parts on the surface, ESD test will be affected.