[{"data":1,"prerenderedAt":64},["ShallowReactive",2],{"blog-pcb-assembly-component-overage-en":3},{"title":4,"description":5,"date":6,"lastUpdated":6,"category":7,"image":8,"readingTime":9,"wordCount":10,"timeRequired":11,"htmlContent":12,"faq":13,"tags":29,"slug":33,"sourceLocale":34,"availableLocales":35,"jsonld":40},"PCB Assembly Component Overage: How to Plan Consigned Parts","Plan consigned PCB assembly parts by BOM line, packaging, setup and agreed attrition, then reconcile used, lost and unused components against the kit record.","2026-10-30","assembly",null,13,2442,"PT13M","\u003Cp>Plan consigned component quantities \u003Cstrong>one approved BOM line and one build at a time\u003C/strong>. Start with the number of parts that must be populated, then add only the setup, attrition, test, rework, or spare quantities that you and the assembler have explicitly agreed. Confirm that the resulting quantity is physically placeable in the supplied packaging—not merely ordered, labeled, or received.\u003C/p>\n\u003Cp>For example, a line requiring 400 populated parts might call for 427 usable parts under one hypothetical agreement: 400 for assembly, 12 separately consumed in setup, and an independent attrition reserve of 15. That is an illustration, not a universal allowance or a HILPCB policy.\u003C/p>\n\u003Cp>This guide addresses the per-line calculation and reconciliation. For the broader document, see \u003Ca href=\"/en/blog/what-is-a-bom/\">what is a BOM\u003C/a>. For who sources the parts, see \u003Ca href=\"/en/blog/turnkey-vs-consigned-pcb-assembly/\">turnkey vs. consigned PCB assembly\u003C/a>.\u003C/p>\n\u003Ch2>What should be included in the quantity?\u003C/h2>\n\u003Ctable>\n\u003Cthead>\n\u003Ctr>\n\u003Cth>Quantity category\u003C/th>\n\u003Cth>Include it when\u003C/th>\n\u003Cth>Avoid double-counting by\u003C/th>\n\u003C/tr>\n\u003C/thead>\n\u003Ctbody>\u003Ctr>\n\u003Ctd>Base population\u003C/td>\n\u003Ctd>The approved variant calls for the part\u003C/td>\n\u003Ctd>Counting only populated positions on boards included in the build\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Setup consumption\u003C/td>\n\u003Ctd>The assembler defines and quotes it as consumed parts\u003C/td>\n\u003Ctd>Checking whether it is already included in an attrition allowance\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Attrition reserve\u003C/td>\n\u003Ctd>The assembler and customer agree on its basis\u003C/td>\n\u003Ctd>Applying it to the agreed denominator and using the agreed minimum and rounding rule\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Test or rework parts\u003C/td>\n\u003Ctd>The parties agree to supply parts for those activities\u003C/td>\n\u003Ctd>Keeping them distinct from an allowance that already covers the same activity\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Customer spares\u003C/td>\n\u003Ctd>The customer wants unused parts retained or returned as spares\u003C/td>\n\u003Ctd>Identifying them separately from parts required for assembly\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Packaging material\u003C/td>\n\u003Ctd>Tape, trays, tubes, or other packaging are needed to present parts\u003C/td>\n\u003Ctd>Not treating empty leader tape as usable parts or automatically as consumed parts\u003C/td>\n\u003C/tr>\n\u003C/tbody>\u003C/table>\n\u003Cp>A reserve is a planning quantity, not a prediction that every reserved part will be lost. Likewise, the assembler’s packaging requirement may affect how parts must be supplied without establishing a fixed consumption quantity.\u003C/p>\n\u003Ch2>Start with the approved population\u003C/h2>\n\u003Cp>For each BOM line, calculate:\u003C/p>\n\u003Cp>\u003Cstrong>Base population = number of boards in the agreed build × populated parts per board\u003C/strong>\u003C/p>\n\u003Cp>The build count must match the scope of the order. If the customer wants additional boards started for yield, engineering evaluation, or another purpose, identify those boards explicitly rather than silently adding an assumed yield factor.\u003C/p>\n\u003Cp>Use the approved BOM, assembly drawing, and variant information to establish the per-board quantity. Check:\u003C/p>\n\u003Cul>\n\u003Cli>Reference designators assigned to the line.\u003C/li>\n\u003Cli>Do-not-populate (DNP) positions for the selected variant.\u003C/li>\n\u003Cli>Parts fitted on only one side or at a particular assembly stage.\u003C/li>\n\u003Cli>Manufacturer part number, package, value, and approved alternates.\u003C/li>\n\u003Cli>Whether the stated quantity is per individual board or per panel.\u003C/li>\n\u003C/ul>\n\u003Cp>Panelization is a frequent source of mistakes. If the BOM quantity is per board, multiply by the agreed board count. If it is per panel, establish how many usable boards and populated positions are represented by each panel before calculating the total. Do not multiply a per-panel quantity by the number of individual boards.\u003C/p>\n\u003Cp>Compare the BOM with the \u003Ca href=\"/en/blog/pick-and-place-file-checklist/\">pick-and-place file\u003C/a> and assembly documentation before releasing the kit. A quantity mismatch may indicate a variant, reference-designator, or file revision problem—not a need for more overage.\u003C/p>\n\u003Ch3>Treat alternates deliberately\u003C/h3>\n\u003Cp>An approved alternate is not automatically interchangeable for kitting purposes. Record its exact manufacturer and part number, approval status, package, quantity, and any restrictions on where it may be used. Agree whether the assembler may substitute it, must segregate it by board or lot, or must request approval before use.\u003C/p>\n\u003Cp>If a line is supplied using more than one part number, calculate and reconcile the quantities for each part number as agreed. Avoid combining their balances into one unexplained total.\u003C/p>\n\u003Ch2>Separate setup from attrition only when the quote does\u003C/h2>\n\u003Cp>Assemblers may describe extra parts in different ways. One quote might include an all-in allowance; another might list setup consumption and an attrition reserve independently. A minimum extra quantity might replace a percentage calculation, apply alongside it, or be included in another allowance.\u003C/p>\n\u003Cp>Ask for the definition before doing arithmetic:\u003C/p>\n\u003Col>\n\u003Cli>What base quantity is the percentage applied to?\u003C/li>\n\u003Cli>Is a minimum a replacement for the calculated percentage, or an additional quantity?\u003C/li>\n\u003Cli>Are setup-consumed parts included in the attrition allowance?\u003C/li>\n\u003Cli>Does the allowance cover multiple reels, lots, or setup events?\u003C/li>\n\u003Cli>What rounding rule applies, and at which calculation step?\u003C/li>\n\u003Cli>Are test, rework, and customer spares included?\u003C/li>\n\u003C/ol>\n\u003Cp>If the quote gives one combined allowance, use that agreed method. Do not add a second setup allowance merely because another supplier uses one.\u003C/p>\n\u003Ch2>Worked example: 427 usable parts\u003C/h2>\n\u003Cp>Assume an approved BOM line has four populated positions per board, and the agreed build is 100 boards. For this example only, the assembler’s hypothetical quote defines \u003Cstrong>12 setup-consumed parts\u003C/strong> and an \u003Cstrong>independent attrition reserve\u003C/strong> of the greater of 3% of base population or a minimum of 15 parts.\u003C/p>\n\u003Ctable>\n\u003Cthead>\n\u003Ctr>\n\u003Cth>Calculation\u003C/th>\n\u003Cth align=\"right\">Parts\u003C/th>\n\u003C/tr>\n\u003C/thead>\n\u003Ctbody>\u003Ctr>\n\u003Ctd>Base population: 100 boards × 4 parts\u003C/td>\n\u003Ctd align=\"right\">400\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Separately defined setup consumption\u003C/td>\n\u003Ctd align=\"right\">12\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Percentage attrition: 3% × 400\u003C/td>\n\u003Ctd align=\"right\">12\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>Independent attrition reserve: greater of 12 or minimum 15\u003C/td>\n\u003Ctd align=\"right\">15\u003C/td>\n\u003C/tr>\n\u003Ctr>\n\u003Ctd>\u003Cstrong>Total usable parts to supply: 400 + 12 + 15\u003C/strong>\u003C/td>\n\u003Ctd align=\"right\">\u003Cstrong>427\u003C/strong>\u003C/td>\n\u003C/tr>\n\u003C/tbody>\u003C/table>\n\u003Cp>The setup quantity and reserve are both hypothetical and explicitly separate. The calculation does \u003Cstrong>not\u003C/strong> add the 12-part percentage to the 15-part minimum; it uses the greater of the two. It also does not add tape length as a number of parts.\u003C/p>\n\u003Cp>This example assumes all 427 supplied parts are accepted as usable and placeable, and that no separate test, rework, or customer spare quantity has been agreed. The reserve may remain partly unused. Actual consumption and returns still need to be reconciled after the build.\u003C/p>\n\u003Ch2>Ordered, received, and placeable are different counts\u003C/h2>\n\u003Cp>A purchase order or reel label does not by itself establish how many parts the assembler can use. Track at least these quantities:\u003C/p>\n\u003Cul>\n\u003Cli>\u003Cstrong>Ordered:\u003C/strong> the quantity requested from the component source.\u003C/li>\n\u003Cli>\u003Cstrong>Shipped or received:\u003C/strong> the quantity recorded in the shipment and at receipt.\u003C/li>\n\u003Cli>\u003Cstrong>Accepted as usable:\u003C/strong> the quantity agreed after the applicable receipt checks.\u003C/li>\n\u003Cli>\u003Cstrong>Placeable:\u003C/strong> usable parts that can be presented in approved packaging for the planned assembly process.\u003C/li>\n\u003C/ul>\n\u003Cp>A full supplier pack may contain more parts than the calculated requirement because of ordering increments. Those extra parts are not automatically consumed or owned by the assembler; their disposition should be agreed.\u003C/p>\n\u003Cp>Conversely, a kit with enough parts on paper may need clarification if tape is damaged, parts are loose, packaging is incompatible, the quantity is uncertain, or the material identification cannot be verified. A part may also be held pending resolution of a packaging or traceability issue. Resolve such conditions before relying on that inventory for the build.\u003C/p>\n\u003Cp>Agree how quantities will be checked, particularly for partial reels and opened packaging. Do not require an inspection method that compromises moisture or ESD protection without agreeing how the parts will be handled afterward. The customer should provide the available packaging and component handling information; the assembler should identify any additional requirements for the quoted process.\u003C/p>\n\u003Ch2>Leader tape is not automatically lost inventory\u003C/h2>\n\u003Cp>For tape-and-reel components, ask the assembler what packaging and feeder presentation are acceptable for the specific part and build. A feeder may need suitable leader material, but \u003Cstrong>a leader requirement is not necessarily a fixed number of populated parts sacrificed\u003C/strong>.\u003C/p>\n\u003Cp>Texas Instruments’ \u003Cem>CC2564MODN data sheet\u003C/em>, SWRS160E, Section 8.2.2, describes device-specific carrier tape with empty portions. It illustrates why empty tape and usable components must be counted separately. It does not establish a general feeder specification for other components or assemblers.\u003C/p>\n\u003Cp>When confirming a tape requirement, ask:\u003C/p>\n\u003Cul>\n\u003Cli>Is empty leader or trailer material acceptable, and what condition must it be in?\u003C/li>\n\u003Cli>Must the populated tape remain in its original reel and orientation?\u003C/li>\n\u003Cli>If populated parts must be removed or otherwise consumed for setup, how many are included in the quote?\u003C/li>\n\u003Cli>Is that consumption already covered by the quoted allowance?\u003C/li>\n\u003Cli>Will a partial or split reel require a separate review or setup?\u003C/li>\n\u003C/ul>\n\u003Cp>Do not convert a physical tape-length requirement into a part count without an agreed, part-specific basis. Empty pockets contain no usable parts to subtract. If populated parts really are consumed during setup, count them only under the applicable agreed allowance.\u003C/p>\n\u003Ch2>Split reels, trays, and lot traceability\u003C/h2>\n\u003Cp>Packaging affects both placeability and reconciliation. Identify whether each line will arrive on a full reel, partial reel, split reel, tray, tube, or another approved format. State the quantity in each package, not just the total for the BOM line.\u003C/p>\n\u003Cp>Multiple packages can mean additional handling or setup, but do not assume a fixed extra quantity per reel. Ask the assembler to quote or confirm the effect for the actual kit. Likewise, a tray or tube may be acceptable for one process but require review for another; agree the format before shipment.\u003C/p>\n\u003Cp>For traceability, provide the available manufacturer labels, lot or date information, and package identifiers. Tell the assembler if lots must remain segregated, if a lot change requires approval, or if the customer needs records connecting supplied lots to the build. Agree the level of recording and the disposition of mixed or unidentified material. Traceability requirements can affect which packages are opened and how remaining parts are returned.\u003C/p>\n\u003Ch2>Plan expensive ICs separately\u003C/h2>\n\u003Cp>A high-value IC deserves its own discussion rather than a blanket percentage copied from a low-cost passive line.\u003C/p>\n\u003Cp>For example, list the expensive IC as a separate line with its exact approved part number, populated quantity, package, available lot information, and proposed supply format. Ask the assembler to identify the usable quantity needed for the planned process, any separately defined setup consumption or attrition allowance, and the treatment of unused parts.\u003C/p>\n\u003Cp>Also agree who may authorize replacement parts if a shortage occurs, whether the customer wants unused material returned, and how nonconforming or damaged parts will be reported. No numerical overage rule is asserted for this line: the appropriate agreement depends on the component, packaging, process, and build.\u003C/p>\n\u003Ch2>What to put in the RFQ and kit release\u003C/h2>\n\u003Cp>Use the \u003Ca href=\"/en/blog/pcb-assembly-quote/\">PCB assembly quote guide\u003C/a> to prepare the overall scope. For each consigned line, include enough information for both quantity planning and receipt:\u003C/p>\n\u003Col>\n\u003Cli>\u003Cstrong>Build identification:\u003C/strong> project, order or build identifier, board count, assembly revision, variant, and panel configuration.\u003C/li>\n\u003Cli>\u003Cstrong>BOM identification:\u003C/strong> BOM revision, line number, reference designators, populated quantity per board or panel, and DNP status.\u003C/li>\n\u003Cli>\u003Cstrong>Part identification:\u003C/strong> manufacturer, full part number, package, approved alternate status, and any substitution restrictions.\u003C/li>\n\u003Cli>\u003Cstrong>Quantity basis:\u003C/strong> base population, quoted setup and attrition method, minimums, rounding, and separately agreed test, rework, or spare quantities.\u003C/li>\n\u003Cli>\u003Cstrong>Kit contents:\u003C/strong> quantity per reel, tray, tube, or other package; total stated quantity; and whether packages are full, partial, or split.\u003C/li>\n\u003Cli>\u003Cstrong>Handling and traceability:\u003C/strong> available labels and lot information, applicable packaging and handling instructions, and any lot segregation or recording requirements.\u003C/li>\n\u003Cli>\u003Cstrong>Shortage authority:\u003C/strong> who may approve an alternate, provide additional consigned parts, or authorize a change to the build.\u003C/li>\n\u003Cli>\u003Cstrong>Return instructions:\u003C/strong> return recipient, usable and nonconforming material disposition, packaging and identification expectations, and treatment of unreturned or retained stock.\u003C/li>\n\u003C/ol>\n\u003Cp>Send the planned kit details with the \u003Ca href=\"/en/quote/\">quote request\u003C/a>, or use \u003Ca href=\"/en/contact/\">contact\u003C/a> to clarify an unusual package or reconciliation requirement before release. The relevant scope may be discussed with HILPCB under its \u003Ca href=\"/en/products/smt-assembly/\">SMT assembly service\u003C/a>; sourcing and assembly responsibilities for a broader engagement should be confirmed under the applicable \u003Ca href=\"/en/products/turnkey-assembly/\">turnkey assembly\u003C/a> agreement.\u003C/p>\n\u003Cp>The customer remains responsible for identifying the supplied parts and providing the agreed kit. The assembler’s receipt checks, quantity confirmation, assembly records, and return handling are responsibilities to define in the project agreement—not assumptions to make from a generic allowance.\u003C/p>\n\u003Ch2>Reconcile the kit after assembly\u003C/h2>\n\u003Cp>Agree on the starting quantity and its verification method before assembly. At closeout, compare that accepted starting balance with the quantities placed, otherwise consumed, returned, retained by agreement, and unresolved.\u003C/p>\n\u003Cp>A useful reconciliation classifies each accepted part into one mutually exclusive \u003Cstrong>closeout\u003C/strong> category:\u003C/p>\n\u003Cp>\u003Cstrong>Accepted starting usable parts + accepted additions during the build = parts fitted on completed or held assemblies + parts irrecoverably consumed or lost + usable parts returned or retained + identifiable nonconforming parts awaiting or assigned a separate disposition + unresolved variance\u003C/strong>\u003C/p>\n\u003Cp>Define the categories and the closeout date before the build. Record separately accepted replenishments as additions. Parts rejected at initial receipt belong in a separate incoming discrepancy record if they were never included in the accepted starting balance. Count a component that was placed and then removed according to its \u003Cstrong>final\u003C/strong> state: for example, a recovered usable part belongs in the returned or retained category, while a scrapped part belongs in irrecoverable consumption. Do not count it both as fitted and returned or scrapped. A replacement that remains fitted is counted once in the fitted category.\u003C/p>\n\u003Cp>Nonconforming material that is still physically held needs its own category; once it has been scrapped, it belongs in the irrecoverable category instead. The unresolved variance is the difference remaining after the other mutually exclusive quantities are accounted for; it can be positive or negative. For expensive or traceability-sensitive parts, agree how opened packages, labels, remaining lots, and rejected material will be identified on return.\u003C/p>\n\u003Cp>The objective is not to force every project into the same reporting format. It is to leave both parties with an agreed account of what was supplied, what the build used, and what remains.\u003C/p>\n\u003Cdiv data-component=\"BlogQuickQuoteInline\">\u003C/div>\n\u003C!-- faq:start -->\n\u003Ch2>Frequently asked questions\u003C/h2>\n\u003Ch3>Is there a standard component overage percentage?\u003C/h3>\n\u003Cp>No universal percentage applies. Use the assembler’s agreed method for the specific line and build, including any minimum and rounding rule.\u003C/p>\n\u003Ch3>Should I add setup parts and attrition for every line?\u003C/h3>\n\u003Cp>Only if the quote defines them as independent quantities. If setup is already included in an all-in allowance, adding it again double-counts.\u003C/p>\n\u003Ch3>Does empty leader tape count against the parts I supply?\u003C/h3>\n\u003Cp>No. Empty tape contains no usable parts. If populated parts must be consumed during setup, agree how those parts are counted.\u003C/p>\n\u003Ch3>Can I send several partial reels instead of one full reel?\u003C/h3>\n\u003Cp>Ask first. Provide the quantity, packaging condition, and lot information for each reel so the assembler can confirm acceptance and any setup implications.\u003C/p>\n\u003Ch3>What happens to unused consigned components?\u003C/h3>\n\u003Cp>Agree the return or retention policy before the build, including identification, packaging, and reconciliation of usable and nonconforming material.\u003C/p>\n\u003C!-- faq:end -->\n\u003Csection class=\"related-links\" aria-label=\"Related\">\u003Ch3>Related links\u003C/h3>\u003Cul>\u003Cli>\u003Ca href=\"/en/blog/what-is-a-bom/\">What Is a BOM in Electronics Manufacturing? PCBA BOM Format, Sample Table, and Sourcing Rules\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/blog/turnkey-vs-consigned-pcb-assembly/\">Turnkey vs Consigned PCB Assembly: How to Assign Material Responsibility\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/blog/pick-and-place-file-checklist/\">Pick-and-Place Files: CPL Fields, Rotation and BOM Matching Checks\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/blog/pcb-assembly-quote/\">PCB Assembly Quote Guide: Files, Cost and Comparison\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/quote/\">quote request\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/contact/\">contact\u003C/a>\u003C/li>\u003Cli>\u003Ca href=\"/en/products/smt-assembly/\">SMT assembly service\u003C/a>\u003C/li>\u003C/ul>\u003C/section>",[14,17,20,23,26],{"question":15,"answer":16,"answerText":16},"Is there a standard component overage percentage?","No universal percentage applies. Use the assembler’s agreed method for the specific line and build, including any minimum and rounding rule.",{"question":18,"answer":19,"answerText":19},"Should I add setup parts and attrition for every line?","Only if the quote defines them as independent quantities. If setup is already included in an all-in allowance, adding it again double-counts.",{"question":21,"answer":22,"answerText":22},"Does empty leader tape count against the parts I supply?","No. Empty tape contains no usable parts. If populated parts must be consumed during setup, agree how those parts are counted.",{"question":24,"answer":25,"answerText":25},"Can I send several partial reels instead of one full reel?","Ask first. Provide the quantity, packaging condition, and lot information for each reel so the assembler can confirm acceptance and any setup implications.",{"question":27,"answer":28,"answerText":28},"What happens to unused consigned components?","Agree the return or retention policy before the build, including identification, packaging, and reconciliation of usable and nonconforming material.",[30,31,32],"component overage","consigned PCB assembly","SMT attrition","pcb-assembly-component-overage","en",[34,36,37,38,39],"de","cn","fr","ru",{"blog":41,"breadcrumb":50},{"@context":42,"@type":43,"headline":4,"description":5,"url":44,"datePublished":6,"dateModified":6,"timeRequired":11,"keywords":45,"articleSection":7,"author":46,"publisher":49},"https://schema.org","BlogPosting","https://hilpcb.com/en/blog/pcb-assembly-component-overage/","component overage, consigned PCB assembly, SMT attrition",{"@type":47,"name":48},"Organization","HILPCB",{"@type":47,"name":48},{"@context":42,"@type":51,"itemListElement":52},"BreadcrumbList",[53,58,62],{"@type":54,"position":55,"name":56,"item":57},"ListItem",1,"Home","https://hilpcb.com/",{"@type":54,"position":59,"name":60,"item":61},2,"Blog","https://hilpcb.com/en/blog/",{"@type":54,"position":63,"name":33,"item":44},3,1794062104499]