### Analysis of Two Major Reasons for FPC Failure
To understand these two reasons, we need to analyze them from Kaboer’s professional design perspective, ensuring sufficient hinge space, and avoiding excessive rigidity in the FPC.
1. The FPC is too short.
2. The material is too rigid; switching to a softer material could resolve this, as it can withstand over 100,000 flex cycles without issue.
Another point to consider is that FPC breakage is a primary concern. In my view, this issue is not particularly challenging. The more critical issue is FPC noise. It is essential to mitigate interference between the FPC and vias. What effective strategies do you have for addressing FPC noise? Common issues related to FPC include breaks that prevent the LCD from displaying and abnormal sounds from the clamshell. Breaks typically arise from insufficient design length or unreasonable hole gap structures in the FPC, while abnormal sounds often occur due to contact and abrasion between the FPC and the shell wall.
In summary, the FPC design should undergo several iterations to achieve optimal results. Using a transparent shell or modifying the shell design can facilitate better observation, allowing for necessary improvements.
It’s also worth noting that some PCB manufacturers may encounter issues during mass production, even if initial prototypes were successful. Therefore, it is crucial to investigate whether the problems stem from material quality.
(1) First, let’s analyze the image of the broken FPC:
1. The fracture is located in the electromagnetic shielding layer of the FPC’s outer layer.
2. As seen in the figure, this layer is folded from the back of the product in the swing area, indicating that it was manufactured separately and then attached to the FPC product.
(2) Possible causes of the fracture:
1. The shielding layer consists of solid copper across its entire surface, which has a high hardness, increasing the likelihood of fracture during the swinging process.
2. Since the shielding layer is separately attached to the FPC and not integrally bonded, it may deviate from the predetermined bending direction during the swing, leading to excessive stress concentration and eventual breakage.
(Thus, the FPC material issue raised by lbmouse is ruled out as the direct cause of the fracture. Additionally, we will not delve into structural issues for now due to the lack of relevant information.)
(3) Recommendations:
1. Wrap tape around the fracture and secure it to the FPC to enhance its adherence.
2. Modify the copper surface of the shielding layer to a mesh design to reduce its hardness.
1. Long-term recommendations:
For the shielding layer in the FPC swing zone, utilizing printed or coated conductors, or bonding specialized conductive cloth for FPC electromagnetic shielding, will effectively eliminate shielding breakage issues without increasing costs.
These are my personal suggestions, and I welcome any feedback.
FPC can incorporate tear-proof lines; for instance, Korean mobile phones feature such lines. Recently, when our company transitioned to domestic production for mobile phones, local manufacturers encountered issues, which were resolved by adding tear lines. Additionally, DOME has outsourced protective films to prevent moisture and dust ingress!
Switching the copper layer of the FPC to a mesh design and increasing the FPC’s deflection should help address this issue, although bundling is recommended only as a last resort. Regarding the fracture in this image, I personally believe it resulted from tension, indicating that the FPC is too short, along with issues related to the FPC via hole, primarily caused by the plastic shell’s mechanism.
This is a hollow structure, reminiscent of bends in mobile phone motherboards.
This twisting occurs when flipping the device. The FPC at B-B in the figure (right) should be repositioned toward the center, allowing for greater torsion deformation and reducing fracture risk.
FPC shielding now frequently utilizes aluminum foil, which performs better for flip covers;
I believe the key to FPC design lies in minimizing stress concentration. The corners should be as rounded as possible. Many internal rounded corners of the FPC are prone to breakage, and enhancing these corners can lead to significant improvements. Avoid placing the shaft’s ends in areas that generate obvious stress (as previously mentioned, connectors should not be positioned too close to the lead-out section of the shaft, as the adhesive layers at both ends of the FPC will experience substantial torsion).
FPC also experiences its own torsion. A longer axial length for the shaft will reduce its inherent torsion, but excessive length may result in noticeable layer-to-layer flapping noise.
The choice of FPC supplier is equally critical. There are electrolytic and rolled copper types used in FPC wires. Of these, electrolytic copper generally has a shorter lifespan, which could affect testing outcomes.
Simulating the FPC length is vital.
In fact, the lifespan of the FPC is also influenced by the chassis structure. Due to frequent movement and limited space within the casing, the FPC will inevitably come into contact with hard surfaces. This is less evident in flip designs but is more pronounced in clamshell phones.
Quality and price are inherently linked. While the value of a single FPC is relatively low, the original components on the board can be quite expensive. Moreover, if damage occurs during the warranty period, the warranty costs can far exceed the value of the FPC.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
To understand these two reasons, we need to analyze them from Kaboer’s professional design perspective, ensuring sufficient hinge space, and avoiding excessive rigidity in the FPC.
1. The FPC is too short.
2. The material is too rigid; switching to a softer material could resolve this, as it can withstand over 100,000 flex cycles without issue.
Another point to consider is that FPC breakage is a primary concern. In my view, this issue is not particularly challenging. The more critical issue is FPC noise. It is essential to mitigate interference between the FPC and vias. What effective strategies do you have for addressing FPC noise? Common issues related to FPC include breaks that prevent the LCD from displaying and abnormal sounds from the clamshell. Breaks typically arise from insufficient design length or unreasonable hole gap structures in the FPC, while abnormal sounds often occur due to contact and abrasion between the FPC and the shell wall.
In summary, the FPC design should undergo several iterations to achieve optimal results. Using a transparent shell or modifying the shell design can facilitate better observation, allowing for necessary improvements.
It’s also worth noting that some PCB manufacturers may encounter issues during mass production, even if initial prototypes were successful. Therefore, it is crucial to investigate whether the problems stem from material quality.
(1) First, let’s analyze the image of the broken FPC:
1. The fracture is located in the electromagnetic shielding layer of the FPC’s outer layer.
2. As seen in the figure, this layer is folded from the back of the product in the swing area, indicating that it was manufactured separately and then attached to the FPC product.
(2) Possible causes of the fracture:
1. The shielding layer consists of solid copper across its entire surface, which has a high hardness, increasing the likelihood of fracture during the swinging process.
2. Since the shielding layer is separately attached to the FPC and not integrally bonded, it may deviate from the predetermined bending direction during the swing, leading to excessive stress concentration and eventual breakage.
(Thus, the FPC material issue raised by lbmouse is ruled out as the direct cause of the fracture. Additionally, we will not delve into structural issues for now due to the lack of relevant information.)
(3) Recommendations:
1. Wrap tape around the fracture and secure it to the FPC to enhance its adherence.
2. Modify the copper surface of the shielding layer to a mesh design to reduce its hardness.
1. Long-term recommendations:
For the shielding layer in the FPC swing zone, utilizing printed or coated conductors, or bonding specialized conductive cloth for FPC electromagnetic shielding, will effectively eliminate shielding breakage issues without increasing costs.
These are my personal suggestions, and I welcome any feedback.
FPC can incorporate tear-proof lines; for instance, Korean mobile phones feature such lines. Recently, when our company transitioned to domestic production for mobile phones, local manufacturers encountered issues, which were resolved by adding tear lines. Additionally, DOME has outsourced protective films to prevent moisture and dust ingress!
Switching the copper layer of the FPC to a mesh design and increasing the FPC’s deflection should help address this issue, although bundling is recommended only as a last resort. Regarding the fracture in this image, I personally believe it resulted from tension, indicating that the FPC is too short, along with issues related to the FPC via hole, primarily caused by the plastic shell’s mechanism.
This is a hollow structure, reminiscent of bends in mobile phone motherboards.
This twisting occurs when flipping the device. The FPC at B-B in the figure (right) should be repositioned toward the center, allowing for greater torsion deformation and reducing fracture risk.
FPC shielding now frequently utilizes aluminum foil, which performs better for flip covers;
I believe the key to FPC design lies in minimizing stress concentration. The corners should be as rounded as possible. Many internal rounded corners of the FPC are prone to breakage, and enhancing these corners can lead to significant improvements. Avoid placing the shaft’s ends in areas that generate obvious stress (as previously mentioned, connectors should not be positioned too close to the lead-out section of the shaft, as the adhesive layers at both ends of the FPC will experience substantial torsion).
FPC also experiences its own torsion. A longer axial length for the shaft will reduce its inherent torsion, but excessive length may result in noticeable layer-to-layer flapping noise.
The choice of FPC supplier is equally critical. There are electrolytic and rolled copper types used in FPC wires. Of these, electrolytic copper generally has a shorter lifespan, which could affect testing outcomes.
Simulating the FPC length is vital.
In fact, the lifespan of the FPC is also influenced by the chassis structure. Due to frequent movement and limited space within the casing, the FPC will inevitably come into contact with hard surfaces. This is less evident in flip designs but is more pronounced in clamshell phones.
Quality and price are inherently linked. While the value of a single FPC is relatively low, the original components on the board can be quite expensive. Moreover, if damage occurs during the warranty period, the warranty costs can far exceed the value of the FPC.
If you have any PCB manufacturing needs, please do not hesitate to contact me.Contact me
