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1、SMT PCB/Panel layout,SMT Team2015-03-22,PCB Design Guideline,Revision record,Purpose,Based on the requirements of production process,In the layout and circuit board design process,There is a standard to follow,To achieve high efficiency in the production of assembly,Easy assembly,low cost,and high q
2、uality target.The content is only applicable to the related database,some are for reference only.,content,PCB layout rulesText marking for silkscreen layer PCB Fiducial Mark designPCB fixed position holeSMT component PAD design PTH component PAD designThrough-hole(Via)designTrace designother limitat
3、ion,PCB layout rules,V-Cut layout rule:Chips to V-Cut line should be more than 1mm,otherwise will damage chips or will change to use Stamp Cut design,will add the PCB cost The distance to PCB edge 0.5mm,can not layout the trace,The distance to PCB edge 1.0mm,can not layout the any component The dist
4、ance to PCB edge 5mm,can not layout the components height over 25mm,otherwise cuter will damage components,PCB layout rules,V-Cut layout rules:PCB trace to V-Cut should be more then S=0.5mm safety buffer,otherwise will have the risk to damage the trace.When we use V-Cut PCB thickness 1.0mm to 3mm(1.
5、0mm to 0.5mm+SMT pallet)PCB outline is square type or rectangle type,irregular shape can not use the V-Cut,irregular shape,PCB layout rules,Stamp design:Stamp design only for irregular PCB,PCB to PCB layout distance is 2mm,V-Cut only 0.3mm Stamp design parameters,PCB layout rules,V-Cut VS Stamp layo
6、ut:PCS to PCS distance only 0.3mm for V-Cut,we can save the PCB layout cost Stamp Cut design,PCB PCS to PCS distance is 2mm Base on same PCS design with different Cut type(stamp/V Cut),the PCB cost will impact 10-25%V-Cut PCB will be cut by machine,but Stamp Cut will broken by OP and have stress the
7、n damage the components,V-Cut machine,PCB/panel layout,Why dont choose single PCB for SMT process:We need to put the each single PCB on carrier when do SMT process But carrier cave and single PCB have tolerance,so always happen solder paste printing misalignment then will get the shift/tombstone pro
8、cess issue Sometimes will happen single PCB lift up from SMT carrier and will have the chips mounting shift/missing process issues,Put the single PCB on the carrier,PCB/panel layout,Factors of impact PCB Cost PCB layout Fine pitch components Panel V-Cut/Stamp Cut/PCB conveyor edge size PCB drill hol
9、e size/quantity PCB material cost PCB process easy/complicated,process spec PCB surface finished process also impact cost,OSP/IMS/EING/IMT PCB outline,regular shape is cheaper than irregular shape,Text marking for silk layer,The current situation:We received the gerber file for UK design team,no sil
10、k layer be found We can not directly confirm Polarity of component on the PCB,can not confirm the location of component,easily to confirm IC shift or not.In the production adjustment X,Y coordinate and confirmation the location completely rely on engineering drawings,Big waste of time.,No silk layer
11、s in the gerber file,No text mark on the pcb,Text marking for silk layer,As the icon text marking design we can accept.We can quickly inspection location where there are problems.,silkscreen,Text marking,Text marking for silk layer,Component outline&polarity marking design definition:Text marking,ke
12、ep away from Via Hole or Through Hole as far as possibleText marking,Silk screen printing character,polarity and polarity signs can not components be coveredText height25 mil,line width 5 milBeside the BGA/CSP,component outline should not smaller than actual component size.The text does not overlapS
13、MD/PTH component text marking include body outline,pin assignment,component name,polarity marking.as below:,Component outline&polarity markingTantalum capacitor or diode 3 PINb.SOP/SSOP,c.QFP,Text marking for silk layer,Component outline&polarity markingd.QFNe.BGA,CSP marking-.outline size must the
14、same as actual component,Text marking for silk layer,PCB number and version(i)PCB Model(ii)PCB Part number and version(iii)text height:80mil PCB 板號說明如下：西元年度後兩碼(06,07)全新 PCB 必需附予板號及-SA(Sample A)版本，爾後修改版本依序為-SB、-SC，或-1A、-1B、-1C.等，量產時版本必需為-1、-2、-3等,Text marking for silk layer,PCB Fiducial Mark design,T
15、he current situation:Many projects did not design fiducial mark-in,the machine can not recognize to position,cause no high precision print/mounted,PCB Fiducial Mark design,L,Three fiducial mark-out located diagonally on board,and do follow related dimension requirement.fiducial mark dimension is 1mm
16、(d)and solder mask is 3mm(D).The diagonal fiducial mark should not be symmetrical,it should be keep away at 5 mm.Fiducial PAD edge keep 4mm distance from the edge of PCB Single board must have two fiducial mark in located diagonally on the board.,Mark out,Mark in,PCB fixed position hole,Tooling hole
17、s on all boards are called out with correct dimensions,tolerances,and are non-plated.(3.55mm+0.075/-0 or 2.18mm+0.05/-0.05)There should be 3.81 mm arc located at 4 corners of PCB to avoid stuck at conveyor and damage of packing material.,Uniform fixed hole size and convenient tool for positioning,To
18、oling holes,3.81 mm arc,NG symptom:0402 chip tombstoneFor example:D500+FN700054 chip 0402 chip tombstone defect rate:1.0%NG picture:,Analysis:PAD to PAD space is too big caused the tombstone after IR.,PAD to PAD:16mil,PAD to PAD:22mil,SMT component PAD design,SMT component PAD design,Non specificati
19、ons within RLC Pad design according to the following principles(i)B=max of W1,to prevent the shift(ii)C=10+H(electrode width)+15 mil(iv)restricted area L2:A+10mil,W2=max:(W1+8+max of tolerance,B+10),(1)Resistance and inductance components size list,0201 PAD design,0402 PAD design,Note:besides the ch
20、ip 0201/0402,the rest of database is for reference only,unit:mil,SMT component PAD design,(2)capacitance component size list,Note:besides the chip 0201/0402,the rest is for reference only,unit:mil,SMT component PAD design,SMT component PAD design,(3)STC32167343,unit:mil,Note:No chips component that
21、size below 0603 located beside 7347 and 6032 tantalum capacitor within 2.6mm pad to pad distance.If un-avoidable,the chip components should be vertical with the tantalum capacitor.,unit:mm,(4)Electrolysis capacitor parts size list,SMT component PAD design,(5)Diode-3PIN,unit:mil,SMT component PAD des
22、ign,(6)Connector pin for Single side,unit:mil,SMT component PAD design,(7)Connector pin for two side,unit:mil,SMT component PAD design,(8)IC types a.SSOP,SOP,unit:mil,SMT component PAD design,(8)IC types b.QFP,unit:mil,SMT component PAD design,IC types(9)QFN,unit:mil,SMT component PAD design,BGA,CSP
23、,unit:mil,SMT component PAD design,PTH component PAD design,In order to simplify and improve the printing circuit welding(soldering)process,The special development of through-hole reflow technology(Pin-in-Paste)The through-hole type connector from Dipping process,change to SMT printing solder paste
24、and reflow replaced.Place all thru-hole parts on topside of the board.(Avoid manual soldering process)B:aperture sizepin diameter size+0.25 mm(10 mil)A:The outer layer of the minimum pad size aperture size+0.36 mm(14 mil)According to the manual soldering parts:Pad size(A)=Hole size(B)+40 mil,PTH des
25、ign guidelineParts of pin diameter and through the aperture ratio(PH)principle:Pin to hole rate(P/H)should fall within 0.60.8,shown as diagram:PH=0.60.8 the best;PH=0.40.5 Acceptable;PH 0.3 not acceptable,PTH component PAD design,If any annular ring of PTH connect with connector or PTH pad,please ad
26、d solder mask to isolate each other(width 20mil at least).,As PSU A000116 Design issue,between PAD with Ground no solder mask covered cause the solder bridge/empty solder.,PTH component PAD design,PTH restricted zone:For pin in paste process,keep at least 3mm distance between edge of hole ring and p
27、ad.,The distance between the PTH and chips too is very close when manual solder has the risk for broken and solder short.besides arrange Ops to manual solder,no choice,Waste a lot of manpower and delay output,PTH component PAD design,Through-hole(Via)design,Via hole under the component bodyVia hole
28、under the smt component body,need to confirm this PCB whether through wave soldering process,if so,need to blind and buried via hole.Otherwise,there will be the risk of overflow from the hole of Via solder.(1)The normal PAD layout(Within the PAD pins)Inner band area(10mil)Via Hole can not be placed.
29、outline band area(10mil),Via Hole can not be placed.,Via hole under the component body(2)Un-normal PAD layout(the pin of the component over the PAD)inner band area(A+10mil)Via Hole can not be placedoutline band area(10mil)Via Hole can not be placed,Through-hole(Via)design,Trace design,Power Trace to
30、 strengthenPAD/Via hole with Trace to junction need to strengthen，the general way(Power Trace，the rest of type refer to Tear drop design),Trace design,Add tear drop In the outer trace add tear drop as below icon:(1)When the line width is less than 8 mil,In pad and trace junction with width of 8 mil
31、and length of 6 mil trace.(2)When the line width is more than 8min,do not add Tear Drop(3)If the distance is not enough to add a Tear Drop,can be ignored.,Trace design,Keep symmetric trace design,Trace lead the way,Trace from the center of the pad,trace,PAD,Trace design,Trace line and the hole,be re
32、commended in the following.,Other limitation,Component placement limitationBoard edge parts restriction(including the process edge size)(i)In SMT stage,there should be no any component body or pad within 4 mm along pcb edge that used for conveyor transfer.(as below the upper and the lower sides),Wit
33、hin 2 mm from pcb edge that vertical to the conveyor.PIP or PTH component body should not out of pcb edge.,Component placement limitation Board edge parts restriction(including the process edge size)(ii)In SMT stage,the component height should lower than 2 mm when it away from pcb edge 46mm(indicate
34、d in pink color region).,Other limitation,Deformation limit B/A7.5/1000,and the maximum deformation of B must be less than 1.2 mm PCB thickness limit:1 1.6 0.127 mm or 10%,PCB substance selectionThe pcb prepreg should meet criteria of Tg 145.The pcb prepreg should meet criteria of Td320.,Other limit
35、ation,PIP parts limitAll of the through hole part must be designed in second to avoid the use of hand soldering process The first surface is necessary to use the SMD TYPE part or through hole parts pin and parts body can not outstand PCB second surface The spec of pin out of pcb surface in PIP proce
36、ss:pin length PCB thickness+0.30.6 mmThe insert parts in PCB can not tilt,dumping or easy to loose state.,Other limitation,Other limitation,Choose the component:The use of chip components in the SMT stage as far as possible,reduce the waste of human action.,PTH parts to SMD,PTH parts to SMD,PTH part
37、s to SMD,PTH parts to SMD,Other limitation,No trace cutting or jump wires process on mass production models.,PCB pad size should be match with the size of components,If the same parts have different appearance size,the Layout or according to process proposals to special Layout,must conform the rule。
38、All of pad design need to non-solder mask design.Passive component pad size The general RLC component：place outline area do not overlap,Do not overlap,Other limitation,For component higher than 5mm,need to keep same distance/clearance on pcb surface free from component to avoid shadow effect and cau
39、sing AOI limiation.,D=H,Other limitation,Gerber file layers requirement,SMD layer:component PAD,reference this layer to design stencil aperture,Gerber file layers requirement,Silk layer:SMD component text marking include body outline,pin assignment,component name,polarity marking,Gerber file layersrequirement,Solder mask layer,Gerber file layers requirement,Place layer:check the component location,Gerber file layers requirement,Drill layer:confirm the through-hole size whether it match with the component,Thank You!,
