Design for Assembly & Kitting Guidelines

PCB Design

1. Fiducials

Fiducial marks are essential for automated assembly. A copper circle has high contrast with the surrounding pcb substrate and is ideal for machine vision recognition. To ensure their effectiveness, they need to be placed in opposite corners with the largest possible diagonal distance between them. They need to be at least 1mm in diameter in the copper layer, with solder mask clearance of 2x copper mark diameter. The following links go into depth on fiducial design.





We prefer two global fiducials, and two locals for each pcb on a panelized design. Edge clearence of 2mm should be observed for panel-tab fiducials. There are certain instances where component density or other design limitations result in boards not having fiducials. In these cases, features like through holes may be used to locate coordinates. We can handle these situations, however dedicated fiducials are ideal.

2. PCB and Panel Size

Individual and panelized designs must have >3mm free space on two opposite edges for SMEMA conveyor clearance. Maximum panel and board size is 460mm x 400mm. Maximum height for surface mount assemblies that need to be reflowed is 25mmm.


Kitting

If you're not ordering turnkey, a few small details can increase process efficiency.

1. Supply extra components. If exact quantities are provided, an error resulting in a wasted component could cause delays. The charts below shows recommended extra part quantities per total placements. Generally, passives and inexpensive parts should have a larger buffer quantity while active and critical parts need only a few additional. Extra components will be returned with finished assemblies.

Required quantities chart for passives and low cost parts
Required quantities for small ICs and midrange parts
Required quantities for BGAs and other expensive parts

2. Component packaging - reels vs. cut tape vs. trays

For automated assembly, either continuous tape on a reel, trays, or tubes are preferred. Multiple strips of cut tape take valuable time to splice and loose parts must be hand placed. THT components can be provided in bulk/loose since they are all hand placed.

3. Shipping

Our shipping address will be provided with your quote. Ensure all bags are marked clearly with part numbers matching your BOM. We don't have requirements for sorting or separating parts for each assembly, especially if different boards share the same line items.


Files

Providing the following files satisfies most or all informational requirements to complete your project.

1. Gerbers with apparent file names in rs274x format - .gtl, .gbl, gto, gbo, gts, gbs, toplayer.gbr, PasteTop.gbr, etc...

2. Position data containing at least X, Y, θ, and designator values. Including other BOM information can be helpful but is not required. - .txt .csv .pos

3. Bill Of Materials containing at least designators and component part numbers. Profiles/Packages, values, quantities, supplier part numbers, and other fields are not required if they aren't already included. - .xls .xlsx .csv