Thank you for your interest in our webinar on perfecting RF PCB prototypes with best DFM practices. It will be presented by Amit Bahl, CRO at Sierra Circuits
Missed the webinar? Click the link below to watch the recording!
You can ask your questions on this thread.
| Question | Answer |
|---|---|
| Can we plate the via with 2mil copper? | Yes, we can plate a via with 2 mil copper. Depending on the desired outcome, there are a couple of ways to achieve this. The standard process involves pattern plating, where copper is plated in the holes and traces. To ensure 2 mil copper in the via, the finished hole size must be large enough to accommodate the plating buildup. For example, if you start with a ½ oz. copper layer on the surface, the final copper thickness will be approximately 2.7 to 3 mil on the surface and 2 mil in the hole. Alternatively, for applications like thermal vias, we can use a separate drill file and perform barrel plating, where only specific holes receive the 2 mil copper before continuing with the rest of the plating process. This method involves additional steps and costs but provides flexibility in plating. |
| What are the key parameters to review for RF PCB? | The key parameters for an RF PCB include material selection and stack-up. RF boards typically have wider traces and larger plane areas, but the most critical factors are the materials used and how the layers are arranged. Common RF materials include PTFE, Teflon, and ceramic-filled Teflons, which are chosen for their electrical properties and ability to support high-frequency signals. Ensuring the right stack-up and selecting materials that meet RF design requirements are essential for optimal performance. |
| Does Sierra do non-magnetic EPIG plating? | Yes, we offer non-magnetic EPIG plating. |
| Can Sierra do ENIG plating wtih leaded solder? And if not what platings are available to use when running leaded solder other than HASL. | Yes, Sierra can do ENIG plating with leaded solder. |
| Can you do back drilling, and how does this affect cost? How do you specify a back drill? What is the tolerance of back drill hole depth? | Yes, we can do back drilling. Back drilling should be specified in the fabrication notes. Our machines use an electronic feedback system that forms a connection between the top of the panel and the tip of the drill bit, ensuring precise depth control. The typical tolerance for back drill hole depth is ±0.5 mil, but in practice, we typically achieve even greater accuracy, around ±0.3 mil. |
| For silkscreen, what is the smallest readable text size? | The smallest readable text size for silkscreen is typically 25 mil high and 4 mil wide. This standard applies when using inkjet technology, though factors such as aspect ratio are also important. If the text is too thick, it can become unreadable. IPC guidelines also define minimum requirements, usually based on aspect ratio considerations. For densely populated boards, achieving clear silkscreen markings can be challenging, so we aim to work within the minimum readable size while accommodating design constraints. If you have specific requirements, we can review them to ensure optimal readability. |
| Does your DFM guidebook include class 3 requirements? | Yes, our DFM handbook has class 3 specs. Additionally, you can check out our design guide on IPC class 3. |
| Do you have a standard Altium design rules file for fabrication with Sierra? If not can we have a meeting with the Sierra team to review the design rules I am currently using in our Altium project template? | We do not have a standard design rules file, as our fabrication capabilities allow for varying design constraints based on specific project needs. We can accommodate tighter tolerances and different design rule sets, but these must be defined at the beginning of the design process. There are advanced material options available, such as those supporting sequential lamination, higher densities, and higher speeds, which enable tighter drill-to-copper ratios and other optimizations. If you’d like to review your current design rules with our team, we’d be happy to set up a meeting to discuss your requirements. |
| Can I just send ONE file, IPC 2581, for Fab and assembly? | Yes, a single IPC-2581 file is sufficient for both fabrication and assembly. |
| What best materials for PCB fabrication can be used to scale an IPC class 3 PCB manufacturing? | Class 3 specifications primarily focus on the ability of the PCB to withstand high temperatures and rigorous conditions. Polyimide materials are commonly specified for class 3 PCBs due to their excellent thermal resistance and durability. The key consideration when choosing materials is ensuring that they meet the thermal and performance requirements specified for the board’s intended application. Therefore, selecting materials that can handle the necessary temperature ranges and other stress factors is essential for class 3 PCB manufacturing. |