PCB Material Selection | PCB Fabricator in India
- What material is best for a design?
- Signal integrity performance (signal speed and signal loss) is often the driving factor in going to a higher cost material set
- Other factors include
- Thermal performance
- Ability to assemble and rework
- Long term reliability
- Going to a ‘higher speed’ material provides improved signal loss (attenuation), but trace lengths also play a major role in determining loss characteristics
- Normally, once speeds of 3Gbps (1.5GHz) are employed, higher speed materials should be considered
- Signal loss on shorter traces is less, and standard high-Tg FR4 can therefore be used at speeds as high as 10Gbps as long as the trace lengths are short enough (a good rule of thumb is 4” or less)
• Material build options
– Full build with desired high-speed material
- Although this will provide superior performance, it will also be the most expensive option and should be used when all PCB layers require improved signal performance
– Hybrid builds
- Often, high-speed signals can fit on just a few of the layers within the build
- Utilizing high-speed materials on either one or both external layers (with standard FR4 on the remaining layers) will provide a desirable performance/cost-benefit
- Utilizing lower cost cores where high-speed isn’t required can also provide lower material costs
- NOTE: Avoid mixing different material prepregs
- Hybrid builds can use a core construction (cores on external dielectrics) in order to maximize dielectric thickness consistency
• Mixed Materials In
- When using a mixed material build, consider the effects of warpage due to the mixing of materials, and take steps to eliminate it
- PWB costs may increase, but the build will be more robust
- Avoid mixing different prepreg materials in the same stack up
- Different prepregs require different press cycles and this cannot be done unless the build is converted to a sequential lamination
- Mixing cores is OK as the cores are already fully cured
• Reliability Cost
• IPC6012 Class 2 vs. Class 3/3A/DS – 10-20% cost adder
- The vast majority of PCB outside of A&D are IPC Class-2
- IPC Class 2 requires cross-sections performed on a sample basis per customer
Most customers don’t request sections
- IPC Class 3/3A/DS requires cross-sections to be done on 100% of the manufacturing
The cost impact is as follows
- Greatly increased lab time for sectioning and report creation
- Coupons must be removed, documented, and stored (up to 20 yrs for some customers)
- More coupons are required for Class 3 products than Class 2, due to sectioning and retention requirements. PCB number up and panelization can be affected
- IPC Class 3/3A/DS requires some special process steps that consume production time and resources
- All panels are serialized to ensure full traceability
- Plating times are 25%-50% longer (1 mil or 1.5mil min vs. 0.8 mil min)
- Additional in-process micro-sectioning is completed in order to ensure compliance with Class 3 requirements for copper and annular ring
- IPC Class 3A requires additional testing (fungus resistance, MIR, rework simulation, ) for which further cost adders apply
As an established PCB Fabricator Supplier in India with an in-depth understanding of the Printed Circuit Board domain including a complete product design life cycle. We have the competence to offer you the finest quality boards within the specification and quantities that you desire.
For more details, visit us;- http://cerrasystems.com/pcb-fabrication/
