PCB Train assembly terms & conditions
IMPORTANT: COMPONENT KITS SUPPLIED BY CLIENTS MUST BE CHECKED PRIOR TO SHIPMENT
Errors in client supplied kits are the most frequent causes of production delay. Do not trust your component supplier. The component distributor's error rate is over 2%. Do not send us component kits directly from distributors without double checking their accuracy. We may find kit supply errors but we do not warrant that we will. We may not identify wrongly labeled components. An error in a free-issue kit supplied to us is your error. We will fit the parts you supply to us. Rectification costs attributable to wrongly supplied parts are additional to our quoted prices.
Count parts and check that quantities agrees with the BOM, after making due allowance for spares (see below). The identity of each component must be checked against the attached label. Check every digit in the part reference, including the tolerance and voltage rating. Check that the component footprint matches the PCB pads.
You may like to consider the advantages of getting us to supply your components. If we supply kits, we take responsibility for all incoming kitting checks, and we guarantee that the all components will be supplied and fitted exactly as your Bill of Materials. Our buying power may make it more cost effective for us to supply your kit. We will ensure that your selected parts are available through normal distibutor channels. Ask us to quote.
Bill of materials (BOM)
A clear and accurate Bill of Materials must be provided. It is invaluable for clarity to include Farnell part numbers. Different types of components should be listed in groups, i.e. 0805 10nf's sequentially, then 0805 100nf's etc. Component values should be clear e.g. 100R, 100K, 100M etc, and not just "100" printed as the value. BOMs must clearly identify parts as either "customer supplied", "PCB Train supplied" or "not fitted".
Component spares
Component kits must be supplied with extra (spare) parts to allow for losses and wastage. 5% extra spares is a reasonable guideline. It is the nature of pick & place machine feeders that parts are wasted at the beginning and end of reels. If we are not supplied with spare parts, we may short ship completed or part built PCBs. Surplus parts will be returned.
Component packaging
Where possible, all SMD components must be supplied taped and reeled. Parts must be supplied in anti-static component bags (generally pink or silver in colour). No static generating materials are permitted on our production floor.
Component packages or bags must be marked as follows:
- parts list item number and/or location designator (e.g. C5)
- quantity
- device description and code
- fine pitch devices must be packaged to avoid damage to their legs.
- moisture sensitive devices must be supplied in sealed bags.
- shipping notes must be included with all parts supplied
PCB pick & place data
It is essential to send us component placement data. This data should include:
- CAD x/y coordinate data in .prn, .csv, .xls, or other editable format.
CAD x/y data must contain columns that include:
- part number (e.g. 1206100NF)
- reference designator (e.g. C12)
- x /y coordinates
- theta rotation angle (e.g.90 deg.)
- placement surface (e.g. top or bottom)
We need easily machine readable data with "one reference designator per line", similar to this format:
Ref Deg Part No. Other info / footprint etc
C1 0805100NF CAP0805 X7R
C2 0805100NF CAP0805 X75
C3 0805100NF CAP0805 X75
C4 0805100NF CAP0805 X75
C5 0805100NF CAP0805 X75
The format example below with "multiple reference designators per line" is a problem to machine read accurately, and is to be avoided:
Ref Degs Part No. Qty
C1,C2,C3,C4,C5 0805100NF 5
Component ident data
Silkscreen, (legend or component ident) data should already be in our possession within the bare PCB manufacturing data package. If not, send the data to cadcam@newburyassembly.co.uk . A schematic diagram of your layout will assist us to resolve any ambiguities about component polarity and physical placement. Send the data to cadcam@newburyassembly.co.uk
PCB Train assembly policies
We will use our best endeavours to place all client supplied parts. Clients have responsibility for supplying a clean kit of parts and for any additional costs arising from client supplied component kit errors. In respect of PCB Train supplied Rs and Cs, where non-standard component values are called for (e.g.123 ohms), we will fit the nearest E24 value such as 120 ohms. Customer supplied components that do not correctly fit the PCB footprint will either be modified to fit (if economic) or returned unplaced with the assembly. Badly labeled components that cannot be cross-referenced to the parts list will be returned to clients with the assembly. If an unclear drawing and/or placement diagram is supplied, we will attempt to contact you and ask you to clarify the information. Parts with ambiguous placement locations may be left unplaced and returned with the assembly.
Quality standards
We will build your Printed Circuit Boards to standard commercial quality (using specification IPC-A-610 Rev C - Class 1, Acceptability of Electronic Assemblies) as a guideline. If you require a different level of quality (perhaps Class 2, or Class 3) for military, medical or other requirements then ask us to quote.
Whilst every effort is made to ensure that you receive a fully functional electronic assembly, we can inspect PCB assemblies at a visual level only. If a fault is subsequently found as a result of an assembly error then we will rework the assembly without charge.
A no-clean 2% silver loaded solder wire will be used for all hand assembly. The colophony- free flux contained within this wire will leave a slight "white-powdery" inert residue around the solder joints. This is non-corrosive and is acceptable within most commercial applications.
PCB design for assembly
BGA footprint pads must be solder resist dammed to ensure adjacent via holes do not wick solder away from the solder ball. Do not put via holes in BGA pads or indeed in any SMD pads. Via holes should be tented or covered with solder resist especially under BGA's to avoid solder paste wicking.
