符合RoHS的穿孔V•I 晶片于焊接时的执行要求.pdf

符合RoHS的穿孔V•I 晶片于焊接时的执行要求pdf,符合RoHS标准，通孔的全尺寸的V•I芯片用于波峰焊接组装。本文档中包含的信息确定所需的工艺条件安装一个全尺寸的V•I芯片到PCB使用波峰焊和手工焊。未能遵循所提出的建议，可导致视觉和功能的模块故障。在除了常见的焊接缺陷的焊接程序，将讨论和方向可提供检测，处理和预防这些缺陷。Application Note AN: 017CHIPFACTORIZED PO WERHand SolderingBefore soldering, make sure that PCB is clean. The pins on the vl Chip are optimized to providea low resistance electrical connection The final mounting scheme for any Vl Chip should bedesigned to minimize any potential mechanical stress on the pins and solder joints. Themaximum clamp pressure for the through-hole vl Chip is 6 lbs. If additional force is required,please contact Applications EngineeringThe time required to create a good solder connection will vary depending on several parameterssuch as PCb thickness, copper trace area, copper trace thickness, soldering iron power, tiptemperature, type of solder, tip size etcThe following typical guidelines apply to hand soldering through-hole vl Chips(1) Tip size: recommended tip diameter of 5 mm(2)Tip temperature: 850%F3)Soldering time: 5 to 10 seconds(4) Type of solder: No clean, 96.5 Sn 3.0 Ag 0.5 Cu(5) Type of flux: Nonesoldering multiple pins of the same potential simultaneously is acceptable. Care should be takennot to short pins of different potentialsWire can be soldered directly to the .l Chip leads. However, any wires soldered to the Vl Chipshould have appropriate strain relief to insure that no stress is applied to the lead frameThe vl Chip itself should be mechanically secured appropriately so that it will not move inthe application and stress the solder connection. Caution should be taken not to cause solderbridging and shorts. Direct wire soldering to the Vl Chip leads is not recommended forproduction applications and should only be used in initial prototyping exercises when a PCBnot availableVICORVicorpower. com800-735-6200Rev. 1.022008cH已3 of 9Application Note AN: 017CHIPFACTORIZED PO WERPin/Lead protrusionPin/Lead protrusion guidelines, defined in IPC-A-61OD, are necessary to enable a good solderconnection. Minimum criteria require the lead end to be discernible in the solder, while themaximum criteria require enough clearance to avoid danger of shorting between leads Figures1-3 and Table 2 show length (1) and the maximum and minimum criteriaFigureLength of leads consideredwithout clinch(left)andh clinch(right)Maximum ( left image) andminimum criteria(right image)MaxFigure 3Example of acceptableprotrusion of soldered lead.TableClass 1*Class 2*Class 3*Maximum and minimumrecommended lead protrusion(L)End is visible in the solder joint (see Figure 3)lengths(L)No danger of shorts 2.5 mm [0.0984 in] 1.5 mm [0.0591Class 1-general electronic products as defined in IPC-A-610 DClass 2-Dedicatede electronic products as defined in IPC-A-610DClass 3-high performance electronic products as defined in IPC-A-610DBoard cleaningIf water-soluble soldsed. the board can be water washedd water No-clealsolders do not require cleaning but will leave residues on the board surface. If this is a concerncleaning can be performed using isopropyl alcoholVICORVicorpower. com800-735-6200Re.1.022008cHE4 of 9Application Note AN: 017CHIPFACTORIZED PO WERSolder Joint Inspection ProcedureA magnifying glass or optical microscope of 10x magnification should be used to look for soldershorts, and solder voiding. Electrical inspection should be conducted to verify any shorting thatot be visibleFigures 4-7 illustrate good solder joints with views from both the bottom and the top sides ofhe PCBGood joint-board bottom sideGood joints- board bottom sideGood joints-board top sideVICORVicorpower. com800-735-6200Re.1.022008cHE5 of 9Application Note AN: 017CHIPFACTORIZED PO WERure 7Good joints on board top sidePotential DefectsSome common detects of soldering through- hole vl chips are described below and illustratedin figures 8-14(1) Solder voiding is caused by outgassing of substances from the solder. To prevent this, acorrect soldering profile should be selected and enough preheat should be provided(2)Non-Wetting is caused by improper chemical characteristics between the solder and the padsurface metallization. Surface plating should be compatible with the solder in order toeliminate non-wetting detects()Fillet lifting is a defect in which solder joints lifts off from the pad. Fillet lifting has beassociated with pb contamination which leads to difference in solder solidification rate atthe interface. the use of bismuth and Lead with lead-free solders should be avoided inorder to avaid fillet lifting(4) Shrink hole and hot tearing defect is related to the appearance of tearing in the solderedints. According to IPC 610 standard this defect is acceptable provided the shrink hole doesnot contact the lead, land or barrel wall(5)Solder balling is related to the presence of solder balls after the soldering operationAdjusting the reflow profile and allowing enough time for soldering can avoid this(6) Insufficient solder is related to solder not filling the through- hole during the soldering processLess than 75% solder fill is not acceptable according to iPC 610 rev D(7) Solder bridging is related to solder improperly connecting two or more adjacent pads andleads that come into contact to form a conductive path during the wave soldering processSolder bridging between joints of same potential is acceptable but should not be expectedFigure 8Solder voidingVICORVicorpower. com800-735-6200Rev. 1.02/2008VChIP6 of 9Application Note AN: 017CHIPFACTORIZED PO WERlon wettingFigure 10Fillet liftingShrink hole/Hot tearFigure 1275 fillInsufficient solder100%75250如Figure 13So/ der ba∥/ngVICORVicorpower. com800-735-6200Rev. 1.02/20087 of 9Application Note AN: 017CHIPFACTORIZED PO WERSolder bridgingRemovalThrough-hole Vl Chip components may be removed from a pCb using a vacuum method1) Preheat assembly(2) Heat each individual joint one at a time in a rapid, controllable fashion to achieve completesolder reflow(3)Avoid thermal and mechanical damage to component board, adjacent components andtheir joints Do not exceed 150 C on the top side(case) of the v. Chip(4) Apply vacuum during lead movement to cool joint and free leadThrough-hole Vl Chips may also be removed using a solder fountain method(1)Reflow all joints in solder fountain(2) Remove old component and either immediately replace with new components or clearthrough-holes for component replacement laterVICORVicorpower. com800-735-6200Rev. 1.02/2008CHIP8 of 9Application Note AN: 017CHIPFACTORIZED PO WERDisclaimerThis document provides general guidelines, which have proven to yield excellent resultsHowever, depending upon equipment, components and circuit boards, the optimal settings maybe different. In order to optimize the soldering process, it is recommended that soldering processexperimentation be performed, optimizing the most important soldering process variables(amount of flux applied, topside preheat temperature, bottom side preheat temperature,recommended preheat profile, maximum ramp rate of topside temperature, conveyor angleconveyor speed, contact time in the solder, solder pot temperature and board orientationMechanical samples of Vl Chips are available to enable optimization of the soldering processPleaseseetheweb(http://www.vicorpower.com/products/accessories/vichip/#samples)forordering detailsPlease contact Applications Engineering for further assistance or inquiries regarding the solderingof through-hole vl Chip components not covered in this documentReferenceFurther information can be obtained from the following web sites and documentsIPC-A-610 Revision D Acceptability of Electronic Assemblieshttp://www.ipc.orghttp://wwwjedec.orgInformation furnished by Vicor is believed to be accurate and reliable. However, no responsibilityassumed by Vicor for its use. Vicor components are not designed to be used in applications, suchlife support systems, wherein a failure or malfunction could result in injury or death. All sales aresubject to Vicor's Terms and Conditions of Sale, which are available upon requestSpecifications are subject to change without noticeVICORVicorpower. com800-735-6200Rev. 1.02/2008age 9 of 9