Analyze the cause of FPC fracture - leading FPC manufacturer

Analysis of two main causes of FPC fracture

To know these two reasons from professional design analysis, hinge space to leave enough, FPC can not be too hard.

1. FPC is too short.

2. The material is too hard, and the soft material may be better. 100,000 times of folding is not a problem.

In addition, FPC fracture is the initial problem, which I personally think is not very difficult, the most deadly is FPC ring, excluding the interference of FPC and hole, you have a good way to FPC ring? There are several problems caused by FPC: LCD does not display and flip tone caused by fracture; Length is too short for fracture, mostly in the design, in addition to wear FPC hole clearance of structure design is not reasonable cause, clamshell different sounds are scratching, FPC and the external shell wall contact in short FPC repeated to try several times to design reach the designated position, had better use the transparent joke, or to cut open a joke, more observation, then make design improvements.

Of course, some manufacturers began to make samples when there is no problem, and then there is a problem in mass production, we must see if it is the problem of the material

(I) It can be seen from the analysis of the fractured FPC picture:

1. The fracture is the electromagnetic shielding layer of the outer layer of FPC

2. It can be seen from the picture that this layer is folded from the back of the product in the swing area, so it can be judged that this layer is made separately and then attached to the FPC product

(II) Prediction of fracture causes:

1. The shielding layer is solid copper with great hardness, which increases the possibility of fracture in the process of swaying.

2. The shielding layer is separately attached to the FPC, which is not a close whole with the FPC product. During the swinging process, it will deviate from the original bending direction, which may lead to excessive stress concentration and fracture.

(Therefore, the FPC material problem mentioned by LbMouse is excluded as the direct cause of fracture. In addition, structural problems are not discussed due to lack of relevant information.)

(III) Suggestions:

1. Bind FPC with adhesive tape at the fracture point to increase its tightness with FPC.

2. Change the copper surface of shielding layer to grid to reduce hardness.

1. Long-term recommendations:

Using printed or coated conductors for the shield in the FPC swing zone, or fitting a conductive cloth specially used for the FPC electromagnetic shield, will completely avoid the problem of shield breakage and will not increase the cost.

The above is my personal advice, I do not know what opinion you prawn.

FPC can design a tear resistant line, Korean mobile phones have tear line. Last time our company's mobile phone was transferred to domestic production, domestic manufacturers began to have problems, and then there was no problem when we added the tear line. DOME also has a protective coating to protect against moisture and dust!

It should be possible to change the copper layer of FPC to copper net and increase the deflection of FPC. However, it is suggested that we have to do this as far as binding is concerned. For the fracture of this picture, I personally think it is caused by pulling, that is, FPC is too short, and there is the problem of FPC through hole, mainly the mechanism of the rubber shell. Now we have used silver paste printing, which can make FPC thinner, and the effect is also good, 100,000 times OK! ]

This basket empty structure, refer to the bending of the mobile phone motherboard.

This is caused by twisting and pulling during flipping. FPC at b-B in the figure (right) should be moved to the middle to lengthen the length of torsional deformation to reduce the possibility of fracture.

FPC screen now a lot of useful aluminum foil, clamshell will be better;

FPC design I think is the most important should reduce stress concentration, rounded corners is must as far as possible big, many cases are in FPC fillet fracture, more rounded corners will be improved substantially, the ends of the shaft do not have apparent stress produced (like about connectors don't stand too close to the people in rotor lead parts, FPC on both ends of the bonding layer can produce a large torque)

FPC also has its own torsional force. If the axial length of the over-axial part is longer, the torsional force will be weakened, but if the axial length is too long, there will be obvious patting sound between layers.

The supplier of FPC is also very important. There are electrolytic copper and calendered copper on the FPC copper wire. The life of electrolytic copper is relatively low, which may affect the test.

The length simulation of FPC is very important, and the analysis of failed parts should be done in one step as far as possible.

In fact, FPC life is also related to the shell structure. Due to the constant need for movement and the limited space in the housing, the FPC will inevitably come into contact with a hard housing. The clamshell is not so obvious. The canopy is not.

Quality is inseparable from price. But FPC individual value is relatively cheap, but its onboard original device is not cheap, and if the warranty period is damaged, warranty costs are much higher than FPC value