Anticipating the Aftermath of Placing Your PCB Orders
Modifying a PCB Design: A Guide for Smooth Transitions
When it comes to modifying a Printed Circuit Board (PCB) design after placing an order, prompt action is key. Here's a step-by-step guide on how to navigate through this process.
1. Initiate Contact Quickly
As soon as you detect the need for a change after placing the order, reach out to your service provider. This could be via their project manager or customer service email. Discuss the change and submit the new design files.
2. Submit Revised Files
Provide revised Gerber files (the standard PCB layout format), updated Bill of Materials (BOM), and Component Placement files (CPL) to reflect the changes. This allows the manufacturer to verify the design and component placement again.
3. Manufacturing Impact and Quote Adjustments
The manufacturer evaluates the change’s feasibility and cost impact. Changes might affect board layers, finishes, or components, which can increase price or lead time.
4. Engineering Change Order (ECO) Usage
In some design environments, software can generate an Engineering Change Order that documents and manages required changes systematically during the multi-board assembly process.
5. Reconfirmation and Approval
After submitting changes, confirm the updated quotation and production schedule with the manufacturer before production continues. If production has already started, incorporating changes may not be possible without scrapping or delaying the batch.
6. Preventive Measures
To minimise post-order changes, designers use tools or plugins to validate and package their fabrication and assembly files carefully before submission.
During the PCB manufacturing process, Design for Manufacturing (DFM) checks are performed to identify potential errors that may occur during the fabrication process. These checks include looking for incomplete design files, trace-width and spacing violations, open traces, drill to copper, and solder mask infringement.
Through-hole components can be mounted manually or with the help of software-controlled machines. If components are not available for manufacture at a reasonable cost, the engineering team may suggest part substitutions or design adjustments to incorporate preferred components.
The bill of materials (BOM) contains the list of components and their specifications required for assembly. Important input files for circuit board manufacturing include Gerbers/ODB, IPC netlist, NC drill file, fabrication drawing, and BOM.
After inner layer imaging, the board undergoes hole creation (drilling), copper deposition/plating, solder mask application, surface finish, and silkscreen application. Solder jet, a programmable device, is used to ensure precise application of the solder onto the board.
X-ray inspection is performed on the completed board to ensure integrity. The BOM is double-checked to ensure it matches the design's parts, and outdated BOMs may be updated with the most recent design information.
Once the board passes all tests, it will be shipped to the provided address through courier partners.
Design for Testing (DFT) ensures the testability of the design and checks for potential test points on the board, the presence of test fixtures, and software as needed. The process of converting design files into a physical circuit board is called circuit board manufacturing.
In the assembly process, Soldering processes such as wave soldering and reflow soldering are used depending on the type of components. High-density pin components require manual insertion due to their unique shape and size.
The assembly process follows Design for Assembly (DFA) which validates each component's source to ensure authenticity and checks for size, spacing, and tolerances for drilled holes, board edge clearance rules, board shape, and thermal reliefs.
At Sierra Circuits, the manufacturing and assembly standards are aligned for prototyping and production of circuit boards for industries such as aerospace, medical, and automotive. Quality testing is conducted in accordance with IPC-A-610, IPC-A-612, and IPC-A-613 assembly standards, and meets ISO:9001:2008, ISO:13485:2003, RoHS, and ITAR requirements.
The Design for Assembly Handbook offers insights on recommended layout for components, common PCB assembly defects, and factors that impact the cost of the PCB assembly, including component packages and board assembly volumes. Similarly, the Design for Manufacturing Handbook offers insights on Annular rings, Vias, Trace width and space, Solder mask and silkscreen.
In the event that changes are required post-order, contact your account manager for assistance.
In the event of necessary changes in the PCB design after an order is placed, promptly contact your service provider to discuss and submit the new design files.
After updating the Gerber files, Bill of Materials, and Component Placement files, the manufacturer needs to reassess the feasibility and cost impact of the changes.
