PCB DFM

DFM ensures that PCB designs align with the capabilities and tolerances of PCB manufacturing machines and materials. This alignment minimizes discrepancies between the intended design and the manufacturable product, streamlining the production process.

The PCB manufacturing process involves multiple stages, each susceptible to potential errors. DFM mitigates delays caused by defective products, errors, and extensive project review and documentation checks. This accelerates time to market, a critical factor in competitive industries.

Highleap’s advanced fabrication equipment and precise processes demand designs tailored to tight machining tolerances. DFM is instrumental in optimizing PCB layouts to meet these rigorous standards, ensuring high-quality, error-free manufacturing and seamless integration with Highleap’s cutting-edge capabilities.

The hole checking process is aimed at identifying possible manufacturability issues within the drill layers, encompassing NPTHs and PTHs (through vias, buried vias, and blind vias), and creating these features. The most crucial aspect is verifying whether the hole table information aligns with the actual files. In cases of information discrepancies, it is imperative to promptly raise an Engineering Question (EQ) to ensure that the design is adjusted to meet manufacturing requirements and can be successfully produced. The following are the checks typically conducted by CAM engineers in the context of PCB drill hole inspections:
Hole Size: Inspecting the diameters and depths of holes in all types, including Plated Through Holes (PTH), Non-Plated Through Holes (NPTH), slots (SLOT), and via layers, to ensure their alignment with the design specifications. Particular attention should be given to verifying the dimensions and shapes of slots.

• Hole Spacing: Examining the distances between holes to ensure adequate spacing, preventing short circuits or manufacturing issues.
• Missing Holes: Identifying any missing holes on non-Surface Mount Device (SMD) pads to ensure that all necessary holes are present.
• Extra Holes: Checking for any redundant holes that may not belong to any pads.
• Power/Ground Shorts: Detecting if holes come into contact with multiple power or ground layers, preventing electrical short circuits.
• NPTH-to-Route Distance: Verifying that holes are not too close to routing paths, potentially necessitating adjustments to avoid manufacturing issues.
• Stubbed Vias: Identifying vias that are not properly connected to at least two copper layers, ensuring electrical connectivity.
• Thermal Connection: Examining the presence of thermal connections for through-hole pin drills to ensure adequate heat dissipation.

These checks contribute to ensuring the accuracy of PCB drill holes and compliance with manufacturing requirements. The expertise and experience of CAM engineers are crucial in preventing manufacturing issues and enhancing manufacturing efficiency. By identifying and resolving potential hole-related issues early on, manufacturing costs can be reduced, and errors and delays in production can be minimized.

During the Design for Manufacturability (DFM) evaluation, Signal and Mixed Layer Checks are instrumental in identifying potential manufacturability issues within signal and mixed layers. These checks aim to uncover any anomalies that may impact the manufacturing process. The checks are versatile and can be applied to any layer, although they primarily focus on signal layers. They rely on the layer itself and any non-copper (NC) layers, such as drill or route layers, that intersect with it.Here’s a breakdown of the specific checks and their purposes:

• Spacing: This check examines and reports spacing violations among various elements, including pads, circuits, and nets. It also identifies spacing irregularities between text elements. Additionally, it detects shorts and spacing discrepancies between different Computer-Aided Design (CAD) nets, highlighting close distances between non-touching features within the same CAD or layer nets.
• Drill: The Drill check reports distance violations between Non-Plated Through Holes (NPTHs), Plated Through Holes (PTHs), and vias, and elements such as pads, circuits, annular rings, and copper. It also identifies any missing pads.
• Route: In this check, distance violations between the edges of route features and pads, circuits, and other relevant elements are reported.
• Size: The Size check reports the dimensions of various elements, including pads, shaved lines, text, line neckdowns, arcs, and shaved arcs.
• Silver: This check focuses on identifying silvers between lines and pads, as well as between different pads. It pays special attention to silver between a text feature and a functional pad, while disregarding silver between two features with the copper text attribute.
• Stubs: The Stubs check is responsible for identifying unconnected line endpoints, ensuring that all connections are established correctly.

These Signal and Mixed Layer Checks play a crucial role in maintaining the integrity of signal and mixed layers within the PCB design. They contribute significantly to the overall manufacturability of the PCB by addressing potential issues and discrepancies that could otherwise lead to production challenges and quality concerns.

Power/Ground Checks play a crucial role in the Design for Manufacturability (DFM) process, particularly in power, ground, and mixed layers of printed circuit boards (PCBs). These checks leverage sophisticated algorithms to detect potential manufacturability issues in both negative and positive power and ground layers. Below are specific details of these checks and their purposes:

• Drill: This check identifies distance violations between Non-Plated Through Holes (NTPHs), Plated Through Holes (PTHs), and vias concerning planes, copper, clearance, and annular rings. It ensures the correct electrical connections and helps prevent shorts.
• Silver: The Silver check reports the presence of silvers in both negative and positive layers. Silvers can lead to unintended electrical connections, which must be rectified to maintain PCB integrity.
• Route: It identifies instances of close spacing between copper/clearance elements and route features. Maintaining appropriate spacing is essential to prevent short circuits.
• Thermal: The Thermal check provides insights into spoke (tie) widths and assesses the reduction of connectivity in thermal pads. Proper thermal connections are vital for heat dissipation and component reliability.
• NFP Spacing: This check reports spacing between Non-Functional Pads (NFPs), NFPs, Non-Plated Through Holes (NTPs), and planes. Adequate spacing is crucial to prevent electrical interference.
• Plane Spacing: It identifies spacing between features situated in different planes. Proper spacing prevents crosstalk and interference between different PCB layers.
• Keep-In/Keep-Out Areas: This check reports the presence of features, whether they are inside or outside Keep-In (Keein) or Keep-Out (Keepout) areas.
• Plane Width: Identifies instances of insufficient copper width between two drills connected to a copper plane. Proper width is essential for electrical conductivity.
• Plane Connection: Detects disconnected areas of copper, which are often used as reference planes. Addressing these disconnections is essential to avoid unreferenced nets or missing electrical connections in the design.

These Power/Ground Checks are indispensable for ensuring PCB manufacturability, reliability, and adherence to industry standards, ultimately contributing to the success of your PCB design.

Solder Mask Checks are a critical component of the Design for Manufacturability (DFM) process, specifically focusing on assessing solder mask layers for potential manufacturability defects. It’s important to note that solder mask layers are considered negative, meaning that all positive features indicate clearance or the absence of solder masks. These checks also verify the presence of solder paste on all Surface Mount Device (SMD) pads. The checks are performed one solder mask layer at a time for each side of the PCB. Below, you’ll find details of the main checks and their purposes:

• Drill: This check identifies instances where there is a close distance to solder mask openings of Plated Through Hole (PTH)/Non-Plated Through Hole (NPTH) annular rings and locations where NPTHs come into contact with the mask. Ensuring proper solder mask clearance around these openings is crucial for preventing solder bridging during assembly.
• Pads: The Pads check reports close distances to solder mask openings for all pads, including undrilled pads. It also evaluates a special group called “gaskets,” providing information about the width of solder mask overlap on features. Adequate solder mask coverage around pads is essential for preventing solder shorts.
• Coverage: This check identifies lines that are positioned too close to clearance areas, indicating inadequate solder mask coverage. Proper coverage is essential for preventing solder bridges between adjacent conductive elements.
• Route: It reports instances of close distance between solder mask and route features. Maintaining appropriate spacing between the solder mask and route elements is essential for preventing assembly issues.
• Bridge: Similar to the Route check, the Bridge check identifies close distances between solder mask and route features, specifically focusing on areas where solder bridges could form.
• Silver: It detects the presence of silvers between solder mask clearance areas. Silvers in these areas can lead to electrical shorts and must be addressed.
• Missing: The Missing check reports any missing clearances in the solder mask layer. Ensuring all necessary clearances are present is vital for preventing electrical shorts during PCB assembly.
• Spacing: This check highlights instances of close spacing between clearance areas, particularly those wider than silvers. Maintaining proper spacing is essential for preventing solder bridging.
• Extra: The Extra check identifies solder mask features that either lack corresponding copper pads or do not intersect with copper. Proper alignment between solder mask and copper elements is crucial for the PCB’s functionality and manufacturability.

Solder Mask Checks are instrumental in ensuring the quality, reliability, and manufacturability of PCBs, particularly in surface mount assembly processes. Addressing any issues identified during these checks is essential for preventing solder-related defects and assembly problems.

Silkscreen Checks are a vital aspect of the Design for Manufacturability (DFM) process, with a specific focus on identifying potential manufacturing defects within silkscreen layers and generating valuable statistics. These checks exclusively operate on silkscreen layers, relying on the job matrix to establish connections with external copper, solder mask, and drill layers, against which they conduct assessments. Below, we outline the primary checks and their purposes:

• Solder Mask Clearance: This check identifies close distances between silkscreen features and solder mask clearance. Ensuring an adequate distance between these elements is crucial for preventing solder mask ink from bleeding onto components or causing electrical shorts.
• SMD Clearance: The SMD Clearance check reports close distances between silkscreen features and Surface Mount Device (SMD) pads. Proper clearance is essential to prevent interference with SMD component placement and soldering.
• Pad Clearance: It identifies close distances between silkscreen features and pads. Adequate pad clearance is necessary to prevent component soldering issues and ensure proper electrical connections.
• Hole Clearance: This check reports close distances between silkscreen features and drills (holes). Maintaining appropriate clearance around holes is essential for preventing mechanical and electrical interference.
• Route Clearance: Similar to hole clearance, the Route Clearance check identifies close distances between silkscreen features and route features. Ensuring adequate clearance around routes is vital for preventing assembly and routing issues.
• Line Width: The Line Width check focuses on identifying violations related to line width and length-to-width ratios. Ensuring that lines meet specified width requirements is crucial for legibility and quality in silkscreen printing.
• String Overlap: The String Overlap check reports instances where silkscreen features with various string values touch or intersect. Addressing string overlap issues is essential for maintaining clear and precise silkscreen markings.

Silkscreen Checks are instrumental in ensuring the accuracy and quality of PCB silkscreen layers, which provide essential visual and reference information on the PCB. By conducting these checks, potential manufacturing defects can be identified and addressed, contributing to the overall success of the PCB manufacturing process.