Errors within kits of components supplied to us by clients as free issue kits are the single most frequent cause of production delays. We advise Clients to open every package received from distributors and to check the contents are exactly as ordered before onward shipment. Our assumption is that client supplied kits are correct. We cannot guarantee to identify wrong components. We will use our best efforts to report errors to clients, however we cannot be held responsible for incorrectly Client identified material.
Benefits for client when supplying free-issue kit:
Disadvantages to client when supplying free-issue kit:
Our Full Procurement Service:
We will always endeavor to machine place components so it is important that supplied material has “tape lead in’s” If necessary we can revise the stencil design based on experience to accommodate various component types.
Components that we are unable to fit will be returned to clients unfitted. Badly labeled Free Issue components, ambiguous placement locations, and unclear drawings may result in non-fitment of parts if such issues cannot be resolved by direct contact with clients.
|Bill of Materials (BOM)|
BOMs should have the normal default information such as reference designator, description, manufacturer and manufacturer part number, quantity. In addition, it is recommended to include Farnell part numbers, and columns to indicate whether the parts are client supplied, or via Wavemar and identify what components are not fitted. It is very useful to have the BOM supplied in an Excel Format.
We typically need 5% extra parts to allow for losses and wastage. Most parts will be assembled using automated pick & place machines. It is inevitable that some parts will be lost from the tape at the beginning and end of production runs due to trial runs and miss-picks. This will not occur on every part, but it could happen on any part. Large parts, and manually placed parts may be supplied to us in the exact quantity.
All components, where possible, should be supplied on tapes and reels. Anti-static precautions should be observed with all packaging.
Component packages or bags should be identified as follows:
|Pick & place machine
It is preferable to send us the pick & place machine component placement data. This will save on programming costs. The data should include the component x/y coordinate data in .prn, .csv, or .xls file formats. Most CAD design software will output a standard pick & place machine component placement file which will be suitable for our needs. There should be columns for:
We generally assemble PCBs to commercial quality based on IPC-A-610 Rev E – Class 2 specification, “Acceptability of Electronic Assemblies”. Inspection/Assembly levels are agreed with the Client at the quoting stage.
We prefer to test product prior to shipment, although batch size and timescales may prevent this. Product will be inspected on a visual basis and AOI if appropriate. Any defects identified during Client Inspection/Test may be returned to for re-work. We can test electronic assemblies either using In Circuit Test, JTag, functional test, power up test, or customer supplied test routines and test rigs.
2% silver loaded solder wire will be used for hand soldered components. This No Clean colophony- free flux leaves a slight “white-powdery” inert residue around the solder joints and is non-corrosive. Normally acceptable for all commercial applications.
SMD solder pastes are again No Clean and are determined (particle size) by the component technology required.
|SMD foot-print design|
Normal pad foot-print design guidelines in line with the Manufacturers specifications should be used.
TIP: ensure that via holes adjacent to BGA pads are covered with solder resist so that solder is not “wicked” away. Via pads should not be placed within BGA pads or SMD pads for the same reason.