1. If PCB routing doesn’t require additional layers, why would one opt for them? Does reducing the number of layers make the PCB thinner? Will the PCB cost be lower if it has one less layer?
2. In some cases, however, adding layers may actually reduce costs.
3. PCBs come in two distinct structural types: the core structure and the foil structure. In the core structure, all conductive layers are embedded within the core material. In the foil structure, only the inner conductive layers are embedded in the core, while the outer conductive layers are formed using a foil dielectric board.
4. A multi-layer lamination process is employed to bond all conductive layers together using an intermediary material. The core material typically consists of a double-sided foil during manufacturing. Since each core has two sides, this remains true even if all conductive layers in the PCB are used. So, why not use foil on one side and a core structure on the other?
5. The main reasons are: the cost of the PCB and the board’s flexural characteristics.
**Cost Advantage of Uniform PCB Boards**
Due to the absence of dielectric and foil layers, the raw material cost of odd-layered PCBs is slightly lower than that of uniform PCBs. However, the processing cost for odd-layered PCBs is considerably higher compared to even-layered PCBs.
While the inner layer processing cost remains the same for both types, the foil/core structure notably increases the processing cost for the outer layer. Odd-layered PCBs require a non-standard cascaded core bonding process in addition to the core structure process. Compared to core-only structures, plants processing boards with foil added outside the core tend to experience lower production efficiency.
Before lamination and bonding, additional processing is required for the outer core, increasing the risk of scratches and etching errors on the outer layer.
**Balancing the Structure to Prevent Bending**
The primary reason to avoid odd-layer PCBs in design is that they are prone to bending. During the cooling phase after the multilayer circuit bonding process, varying lamination tensions can cause the PCB to warp as the core and foil structures cool at different rates. As the board thickness increases, the risk of bending becomes greater for composite PCBs with two distinct structures.
The key to preventing PCB bending is to achieve a balanced stack-up. While the PCB may have some curvature that still meets specification requirements, this can reduce subsequent processing efficiency, leading to higher costs.
Assembly of these boards requires specialized equipment and processes, and the accuracy of component placement may be compromised, negatively impacting overall quality.
**Solving PCB Layout Issues for DC/DC Converters**
When designing PCBs with uneven layers, several strategies can be employed to achieve balanced stacking, reduce production costs, and prevent PCB warping:
The following methods are listed in order of preference:
1. **Use a Uniform Signal Layer:**
This method is effective when the PCB’s power layer is uniform, and only the signal layer is odd-numbered. Adding an extra layer won’t significantly increase costs, but it can shorten delivery times and improve overall PCB quality.
2. **Add an Extra Power Layer:**
This method is applicable if the PCB’s power layer is odd, and the signal layer is even. One way to address this is by adding a layer in the middle of the stack-up without altering other design parameters. First, use the odd-layer PCB layout and then insert the remaining layers in the middle. This approach maintains similar electrical properties to the foils used in thickened stack-ups.
3. **Introduce a Blank Signal Layer Near the Center of the Stack-Up:**
This strategy helps minimize stack-up imbalance and enhances PCB quality. Begin with routing through the odd-numbered layers, then add a blank signal layer, followed by the remaining layers. This approach is particularly useful for microwave and mixed-dielectric constant circuits, where different mediums require varying dielectric properties.
**Advantages of a Balanced Cascaded PCB:**
– Lower cost
– Reduced risk of bending
– Shorter delivery times
– Improved overall quality
If your have any questions about PCB ,please contact me info@wellcircuits.com
2. In some cases, however, adding layers may actually reduce costs.
3. PCBs come in two distinct structural types: the core structure and the foil structure. In the core structure, all conductive layers are embedded within the core material. In the foil structure, only the inner conductive layers are embedded in the core, while the outer conductive layers are formed using a foil dielectric board.
4. A multi-layer lamination process is employed to bond all conductive layers together using an intermediary material. The core material typically consists of a double-sided foil during manufacturing. Since each core has two sides, this remains true even if all conductive layers in the PCB are used. So, why not use foil on one side and a core structure on the other?
5. The main reasons are: the cost of the PCB and the board’s flexural characteristics.
**Cost Advantage of Uniform PCB Boards**
Due to the absence of dielectric and foil layers, the raw material cost of odd-layered PCBs is slightly lower than that of uniform PCBs. However, the processing cost for odd-layered PCBs is considerably higher compared to even-layered PCBs.
While the inner layer processing cost remains the same for both types, the foil/core structure notably increases the processing cost for the outer layer. Odd-layered PCBs require a non-standard cascaded core bonding process in addition to the core structure process. Compared to core-only structures, plants processing boards with foil added outside the core tend to experience lower production efficiency.
Before lamination and bonding, additional processing is required for the outer core, increasing the risk of scratches and etching errors on the outer layer.
**Balancing the Structure to Prevent Bending**
The primary reason to avoid odd-layer PCBs in design is that they are prone to bending. During the cooling phase after the multilayer circuit bonding process, varying lamination tensions can cause the PCB to warp as the core and foil structures cool at different rates. As the board thickness increases, the risk of bending becomes greater for composite PCBs with two distinct structures.
The key to preventing PCB bending is to achieve a balanced stack-up. While the PCB may have some curvature that still meets specification requirements, this can reduce subsequent processing efficiency, leading to higher costs.
Assembly of these boards requires specialized equipment and processes, and the accuracy of component placement may be compromised, negatively impacting overall quality.
**Solving PCB Layout Issues for DC/DC Converters**
When designing PCBs with uneven layers, several strategies can be employed to achieve balanced stacking, reduce production costs, and prevent PCB warping:
The following methods are listed in order of preference:
1. **Use a Uniform Signal Layer:**
This method is effective when the PCB’s power layer is uniform, and only the signal layer is odd-numbered. Adding an extra layer won’t significantly increase costs, but it can shorten delivery times and improve overall PCB quality.
2. **Add an Extra Power Layer:**
This method is applicable if the PCB’s power layer is odd, and the signal layer is even. One way to address this is by adding a layer in the middle of the stack-up without altering other design parameters. First, use the odd-layer PCB layout and then insert the remaining layers in the middle. This approach maintains similar electrical properties to the foils used in thickened stack-ups.
3. **Introduce a Blank Signal Layer Near the Center of the Stack-Up:**
This strategy helps minimize stack-up imbalance and enhances PCB quality. Begin with routing through the odd-numbered layers, then add a blank signal layer, followed by the remaining layers. This approach is particularly useful for microwave and mixed-dielectric constant circuits, where different mediums require varying dielectric properties.
**Advantages of a Balanced Cascaded PCB:**
– Lower cost
– Reduced risk of bending
– Shorter delivery times
– Improved overall quality
If your have any questions about PCB ,please contact me info@wellcircuits.com
