Documentation requirements:¹

• Bill of Materials to include: manufacturer’s part number, type of part², type of packaging³, topside or bottomside assembly, component locations listed by reference designators and quantity. (download an "Excell" template)

• Assembly drawing⁴, including any change notices.

• Dimensional specifications for non-standard⁵ components

• Solder paste stencil file in "Gerber" format 274X.

• Electronic "Centroid data" in ASCII format. This is the "X" & "Y" coordinates for the location of the parts on the board. These coordinates should reflect the location of the center of the component body referenced to the same zero point. This information should also include the respective component designations as well as the component rotation. The preferred format for coordinates is in millimeters. (please call for info if you are unfamiliar with this)

• Circuit board designs shall provide for fiducial⁷ marks to be used for registration of boards or panels. Fine pitch components with spacing of 25 mils or less should include 2 fiducials for placement verification. One should be in the center and the other should be diagonally placed to the outside edge of the component.

• All panel arrays or boards must have a minimum of two tooling holes diagonally opposing in the corners of the panel.

• There must be a minimum of 0.25" space clearance from any edge of the panel to the edge of the nearest component body.

• Circuit boards must meet bow and twist specifications of IPC–D-600.

• Maximum board or panel accepted for assembly is 12" x 14".

• When boards are small, it is advised that the boards be arrayed in panel form and scored whenever possible in order to cut down on the handling time and cost.

• The finish on the surface mount pads must exhibit a property of flatness to allow for proper placement of SMT components. This property becomes more critical as the pitch becomes smaller. Examples of a preferred flat finish would be Ni/Au(immersion gold over electroless nickel), OSP(Organic Solderability Preservatives) or Electroless Palladium(recommended). Soldermask should cover all traces and exhibit good registration.

• SOIC components should be supplied in either tubes or on tape and reel. PLCC components should be supplied in trays, tubes or on tape and reel. QFP components are to be packaged in trays. To prevent damage to QFP’s, do not remove from original provided trays and do not break hermetic seal.  Tape and reel are preferred for all components whenever possible.

• All SMT components provided on tape and reel should have a factory-attached leader approximately 12" long before the first component.

• Please provide 5% attrition for all parts provided on tape and reel and 2% attrition for all other forms of packaging. Unused parts will be returned after completion of assembly.

• The first time we set-up a new assembly for SMT, it is both important and necessary that we verify solder paste stencil set-up, placement programming, feeder set-up and optimization, placement accuracy and oven profile for proper reflow of the solder paste with the components mounted. It is not recommended that these parameters for proper assembly be learned "on the fly". The multitudes of possible problems encountered during this exercise are far too numerous to list. These potential problems must be identified and corrected before the production order is run through the entire sequence of events required for proper SMT assembly. It may often be required that we build 1 or 2 assemblies for purposes of proofing the set-up. It is possible that these boards may or may not be usable after this exercise. We will not mount components identified as expensive for this proofing and we request that if you are the supplier of the boards, please send any extra bare boards that you may have on hand. These bare boards may be scrap due to damage or defects in manufacturing, extras, or possibly an older revision that has become obsolete, but please identify them as scrap to be used for test purposes only.

Questions concerning the above requirements or the manufacturing capabilities of Circuit Services can be answered by calling 504-468-9714, faxing 504-468-9726 or email questions to smt@circuitservices.com. We welcome you to visit our website at www.circuitservices.com

Notes:

¹ Documentation may be supplied as a "WORD" file, "EXCEL" file or hard paper copy.
² An example of a "type of part" is: SOIC-8 pin, QFP-160 pin, PLCC-84 pin, etc.
³ An example of a "type of packaging" is tube, waffle tray, 8mm tape, 12mm tape, bulk, etc.
⁴ Drawings may be supplied as "Gerber" files, "DXF" files or hard paper copies.
⁵ Non-standard SMT components are defined as connectors, headers, sockets, transformers, LEDs, etc.
⁶ Circuit board requirements apply for circuit boards supplied by customer and not manufactured at CSI.
⁷ Fiducial marks are isolated targets placed on the board for the purpose of verifying registration of the board, panel or component location during assembly. Board/panel fiducials are usually placed diagonally opposing on two of the outside corners. There should be a minimum soldermask clearance of .015".
⁸ Component requirements apply for all components supplied by customer and not supplied by CSI.