QFN Mounting Manual - Renesas Electronics
Contents
1. 15 16 7 1 Overview of QFN Package Pin End Surface aaaaaasassssssssssssssrsssssssssssssssssa 16 7 2 Visual Comparison of Air Reflow and Nitrogen Reflow Mounting 17 e On Board Mechanical Stress Test RESUS p sa ia tina aie eina o imas ia e ea siena I e P dE 18 IK On Board Relhabiliy Test Resglu uu u u uu 19 9 1 Board Mounted Thermal Cycle Test Results punching cut type 6 x 6 mm 0 4 mm pitch 19 9 2 Board Mounted Thermal Cycle Test Results dicing cut type 5 x 5 mm 0 5 mm pitch 19 9 3 Board Mounted Thermal Cycle Test Results dicing cut type 7 x 7 mm 0 5 mm pittch 20 9 4 Board Mounted Thermal Cycle Test Results dicing cut type package shape dependency 20 10 QFN Reworking removal from the mounting boatrd 21 R50ZZ0005EJ0150 Rev 1 50 5 Contentst Mar 25 2015 QFN Mounting Manual 1 The QFN Package 1 The QFN Package The QFN Quad Flat No lead package is low profile package with a leadless structure It is appropriate for use in portable and other equipment that requires miniaturizatio2. Electronics products or technology described in this document you should comply with the applicable export control laws and regulations and follow the procedures required by such laws and regulations It is the responsibility of the buyer or distributor of Renesas Electronics products who distributes disposes of or otherwise places the product with a third party to notify such third party in advance of the contents and conditions set forth in this document Renesas Electronics assumes no responsibility for any losses incurred by you or third parties as a result of unauthorized use of Renesas Electronics products This document may not be reproduced or duplicated in any form in whole or in part without prior written consent of Renesas Electronics Please contact a Renesas Electronics sales office if you have any questions regarding the information contained in this document or Renesas Electronics products or if you have any other inquiries Note 1 Renesas Electronics as used in this document means Renesas Electronics Corporation and also includes its majority owned subsidiaries Note 2 Renesas Electronics product s means any product developed or manufactured by or for Renesas Electronics 2012 4 QFN Mounting Manual Table of Contents li OOP J 1 1 1 Punching Cut Type Sms ul at FOR uuu u u KEA a I icine ue Tyee SAW Singnlatien i uuu uu 2 1
3. Pin section outer G Pin section outer b2 Pin section aperture width E2 Die pad one divided die pad area Figure 3 3 Stencil Design Example when the die pad is divided into 4 sections Table 3 2 Stencil Design Example punching cut type Unit mm Component External Pins Side Pin Pitch Die Pad Pin Section Die Pad Thick Size of Pin pin size Exposure 100 aperture for the mounting 60 aperture for the mounting ness board Cu pad area board Cu pad area Number of bxL S E2 Sh eee pe f I 05 022 040 460 aoo l ts ek G Te e eee e 39 Table 3 3 Stencil Design Example dicing cut type 0 5 mm pitch Unit mm External Number Pins Side Pin Pitch Die Pad Pin Section Die Pad Thick Size of Pins pin size Exposure 90 aperture for the mounting 60 aperture for the mounting ness board Cu pad area board Cu pad T uw Number of L Size E2 PE Sein mE _ ELI R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 8 of21 Mar 25 2015 QFN Mounting Manual 3 Solder Paste Printing Table 3 4 Stencil Design Example dicing cut type 0 4 mm pitch Unit mm Component External Pins Side Pin Pitch Die Pad Pin Section Die Pad Thick Size of Pin pin size Exposure 100 aperture for the mounting 60 aperture for the mounting ness board Cu pad area board Cu pad area Number of L E2 e B pum Hpo es x vas i 6
4. that supports the die pad in the corner 15 exposed at the package end We do not recommend soldering to this section Since the characteristics of the semiconductor device itself may be affected if electrical contact 15 made to the corner pin we recommend that users consider mounting pad design that takes contact with the corner pin section into account A design example for P VQFN48 6x6 0 4 package is presented below Contact with the die pad hanging lead is avoided by designing B1 to be shorter than that for other pads No Exposed Pad Exposed Pad Exposed Pad Die pad hanging lead Die pad hanging lead IILI SOTTO KO 5 NIT M E ELI Ea Ti ililili x Figure 2 3 Die Pad Hanging Lead Example Figure 2 4 Design Example when a Die Pad is Present 2 4 Mounting Pad Design Examples See the Renesas web site for mounting pad design examples for each QFN package code http www renesas com products package information ic name list index sp R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 5 of 21 Mar 25 2015 KENES QFN Mounting Manual 3 Solder Paste Printing 3 Solder Paste Printing 3 1 Solder Paste The main components of solder paste are solder powder and flux The particular solder paste used should be chosen based on the usage conditions adopted 1 Solder Powder Due to the desire to eliminate lead from manufacturing processes due to environment consideration
5. 3 Lead Surface Processing Speclifications I 2 2 Mounir 3 2 1 Pad iO i C Tm eem 3 22 Niountina Pad Desen tes assem ENG 4 2 3 Notes on Mounting Pad Design punching cut type 5 24 Pad Desioen Examples u uuu uuu 5 32 6 T G ee oot 6 3 1 BO L TTT un sos DN xa mu Ka 6 3 2 I MTM X K V i 2d Puckast u UN NUN o 10 4 1 Board Mounting Placement Condltions 10 De Below Thermal Be SIS GIC 12 5 1 Storage Prior to Opening Moisture Proof Packing 12 5 2 Storage After Opening Moisture Proof PacKing 12 E 12 5 4 Number of Reflow 13 39 S NE m c cc 13 56 bolderip 14 O il T E
6. 4 45 45 section CO 10 85 85 103 R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 9 of 21 Mar 25 2015 KENES QFN Mounting Manual 4 Package Placement 4 Package Placement 4 1 Board Mounting Placement Conditions Since the area of the resin sealed surface and the area of the solder connection pin surface are essentially identical in QFN packages there are cases where the solder paste 1s forcibly spread causing problems when placing a package on the mounting board In particular this phenomenon becomes significant with QFN packages that are 5 x 5 mm and smaller The user must look into the load used during package placement the distance the package is pressed into the solder and other aspects and determine appropriate mounting conditions The tables below list results obtained in house here at Renesas 1 Die pad connection present 100 solder printing of the die pad area Note Stencil thickness 0 1 mm 2 Die pad connection present 60 solder printing of the die pad area divided into 4 sections Note Stencil thickness 0 1 mm Placement Conditions Overview Placement speed Spring load placement load Press in distance HHHHHHHHHHHU Evaluation standard OK No paste bridges occur at package placement NG Paste bridges occur at package placement Figure 4 1 Placement Conditions From the above we recommend the following to suppress paste spreading at package pla
7. 5 mm pitch 1096 1 Cu Ni Pd Au plating painted wiing Size 124 190 t1 6 mm pear Material FR 4 4 layers Pad surface processing Cu OSP T T 1 aren sss L Reflow soldering Sn 3Ag 0 5Cu paste 240 C max 1 10 100 1000 10000 100000 temperature 40 to 125 C 10 min to 10 min cycle leads Figure 9 4 Weibull Plot i i Failure definition 20 nominal resistance increase Eevaluation results of temp cycle on board R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 20 of 21 Mar 25 2015 QFN Mounting Manual 10 QFN Reworking removal from the mounting board 10 QFN Reworking removal from the mounting board Although it 1s not possible to repair boards with a soldering iron after QFN package devices have been mounted it is possible using special purpose equipment The following points must be observed in the reworking method used e The influence of the heating on adjacent pins must be minimized e Since the heating conditions will differ due to differences in the heat capacities of the printed wiring board board thickness number of layers and mounted components used Therefore the conditions must be set to correspond to the actual product and its mounted components e Consult the manufacturer of each component to determine if mounted components can be reused after reworking Note Renesas quality guarantees do not apply to components that have been remo
8. P R China 200333 Tel 86 21 2226 0888 Fax 86 21 2226 0999 Renesas Electronics Hong Kong Limited Unit 1601 1611 16 F Tower 2 Grand Century Place 193 Prince Edward Road West Mongkok Kowloon Hong Kong Tel 852 2265 6688 Fax 852 2886 9022 Renesas Electronics Taiwan Co Ltd 13F No 363 Fu Shing North Road Taipei 10543 Taiwan Tel 886 2 8175 9600 Fax 886 2 8175 9670 Renesas Electronics Singapore Pte Ltd 80 Bendemeer Road Unit 06 02 Hyflux Innovation Centre Singapore 339949 Tel 65 6213 0200 Fax 65 6213 0300 Renesas Electronics Malaysia Sdn Bhd Unit 1207 Block B Menara Amcorp Amcorp Trade Centre No 18 Persiaran Barat 46050 Petaling Jaya Selangor Darul Ehsan Malaysia Tel 60 3 7955 9390 Fax 60 3 7955 9510 Renesas Electronics India Pvt Ltd No 777C 100 Feet Road HAL II Stage Indiranagar Bangalore India Tel 91 80 67208700 Fax 91 80 67208777 Renesas Electronics Korea Co Ltd 12F 234 Teheran ro Gangnam Gu Seoul 135 080 Korea Tel 82 2 558 3737 Fax 82 2 558 5141 2015 Renesas Electronics Corporation All rights reserved Colophon 4 0 QFN Mounting Manual LENESAS Renesas Electronics Corporation R50ZZ0005EJ0150 QFN Mounting Manual 424 NE SAS Renesas Electronics Corporation R50ZZ0005EJ0150
9. Sn 3Ag 0 5Cu paste 245 C max 1 10 100 1000 10000 100000 temperature 55 to 125 C 10 min to 10 min cycle leads Figure 9 1 Weibull Plot Eevaluation results of temp cycle on board 9 2 Board Mounted Thermal Cycle Test Results dicing cut type 5 x 5mm 0 5 mm pitch The results of an evaluation of the effects of whether or not die pad soldering was used are shown below This testing showed that die pad soldering has an effect on solder connection reliability Table 9 2 Evaluation Specs Test temperature 40 to 125 C 10 minutes dwell Package P WQFN32 5x5 0 5 Lead material Cu Lead plating Ni Pd Au Printed wiring Size 124 x 130 x t0 8 mm board Material FR 4 4 layers Weibull Plot F t 999 lI I minm Lo 959 889 LL LLLI III Solder paste Sn Ag Cu without E Pad soldering ONI rin Solder paste Sn Ag Cu with E Pad soldering MEE PI u Fri TAI I pb e oe 7 R EUCH Pad surface processing Cu OSP J aperture 1 25 mm square x 4 Reflow soldering Sn 3Ag 0 5Cu paste 240 C max 1 10 100 1000 10000 100000 temperature 40 to 125 C 10 min to 10 min cycle leads Figure 9 2 Weibull Plot i i i Failure definition 20 nominal resistance increase Eevaluation results of temp cycle on board i 0 1 R50Z
10. factor of 0 9 in the width direction to prevent bridging and the amount of paste applied must be about 90 of the mounting pad area 2 Die Pad Exposed Sections When designing a stencil for an exposed die pad type QFN package the die pad section aperture design should be about 60 of the die pad This is because if the aperture design was 100 the package placement load would forcibly spread the solder and the mountability would be adversely affected Below we show evaluations for amount of forced spreading due to the load when placing packages for 100 printing and for 60 printing divided There is concern that with 100 printing the solder may be forcibly spread by the placement load and shorting to pins occur We recommend that the user verify the results of actual placement evaluations Also since the area of the die pad section 15 large compared to the pin area the solder will have a large wetting force and the amount of solder applied to this area may adversely influence the mounting height after reflow MEER 100 Printing 60 Printing divided Printing Completed Mounting Completed Note Stencil thickness 0 1 mm Figure 3 2 Visual Inspection Photographs of Solder Spreading at Package Placement Model package test using glass plates R50ZZ20005EJ0150 Rev 1 50 LENESAS Page 7 of21 Mar 25 2015 QFN Mounting Manual 3 Solder Paste Printing The figure below shows a sample stencil design for a QFN package Z
11. pad dimensions include the following e Soldering strength 1 e Solder mask pattern precision and soldering visual inspectability B2 e Solder bridge tolerance y The way the margins for each dimensional area are determined depends on the user s approach to pattern design and the application the equipment will be used in We recommend that users design QFN printed wiring board mounting pads based on the approach shown below which 15 similar to that for QFP packages N Lp Pin flat section length b Pin width b Lp L2 gt Lp B1 B2 L2 mounting pad length b2 b lt b2 lt e y b2 mounting pad width p1 p2 Figure 2 2 Mounting Pad Design Parameters Table 2 1 Design Reference Values Unit mm md 0 to 0 30 0 to 0 20 0 10 to 0 30 0 10 to 0 30 0 10 to 0 20 Notes 1 The mounting pad pitch must be the linear pin spacing pin pitch for the package being mounted 2 We do not recommend mounting on the wiring board the lead that is exposed at the package corner die pad hanging lead for the punching cut type QFN package If required we recommend that users analyze the package end land B1 dimension taking contact with corner exposed leads into account R50ZZ20005EJ0150 Rev 1 50 LENESAS Page 4 of 21 Mar 25 2015 QFN Mounting Manual 2 Mounting Pads 2 3 Notes on Mounting Pad Design punching cut type In the punching cut type QFN package part or all of the lead hanging lead
12. NES QFN Mounting Manual 7 Misual Inspection 7 Visual Inspection With the earlier lead type SMD packages the solder defects that occurred included solder balls wicking solder not connected and shorting These defects could be detected with either visual inspection or inspection using some sort of optical system QFN package soldering defects include solder not connected and shorts However since the solder connections are made underneath the package they cannot be detected with inspection methods that use an optical system Although shorting defects can be detected with transmission X ray units solder not connected defects cannot be detected There are now three dimensional detection methods that have been developed for inspection of locations such as the areas under the packages that cannot be seen visually These include tomosynthesis methods and laminography methods that use a scanning X ray beam Currently the equipment listed in the table below is available commercially as equipment for performing post soldering visual inspections However there are products whose operation can be influenced by exposure to X rays so adoption of these methods requires careful verification in advance Table7 1 Visual Inspection Equipment Inspection Method Details of the Inspection Method Optical systems Integrated laser sensor rotating scan method Color highlight method Combined laser and multi camera method Laser scanning method X ray meth
13. Z0005EJ0150 Rev 1 50 lt 2 AS Page 19 of 21 Mar 25 2015 KENES QFN Mounting Manual 9 On Board Reliability Test Results 9 3 Board Mounted Thermal Cycle Test Results dicing cut type 7 x 7 mm 0 5 mm pitch The results of an evaluation of the effects of whether or not die pad soldering was used are shown below This testing showed almost no effect of die pad soldering on solder connection reliability Table 9 3 Evaluation Specs Test 40 to 125 C 10 minutes dwell temperature Package P WQFN48 7x7 0 5 Lead material Cu Lead plating Ni Pd Au Printed wiring Size 124 x 130 x t0 8 mm TI TERN HERE LUI poate Material FR 4 4 layers 1 10 100 1000 10000 100000 temperature 40 to 125 C 10 min to 10 min cycle leads Figure 9 3 Weibull Plot Eevaluation results of temp cycle on board Weibull Plot EI PI 14 Solder ps Sn Ag Cu without E Pad 70618 H L E IL 5 1 Pad surface processing Cu OSP 9 4 Board Mounted Thermal Cycle Test Results dicing cut type package shape dependency This testing showed that the smaller the package the greater the effect on connection lifetime Table 9 4 Evaluation Weibull Plot F t eibu WE Tasson HEPER 5 x 5 mm 32 pins 0 5 mm pitch 60 FMI FEINO Fil i Mi 18 mH 7 x 7 mm 48 pins 0 5 mm pitch H m m A Ti 9 x 9 mm 64 pins 0
14. au m o lt CO D QFN Mounting Manual All information contained in these materials including products and product specifications represents information on the product at the time of publication and is subject to change by Renesas Electronics Corp without notice Please review the latest information published by Renesas Electronics Corp through various means including the Renesas Electronics Corp website http www renesas com Renesas Electronics WWW renesas com Rev 1 50 Mar 2015 10 11 12 Notice Descriptions of circuits software and other related information in this document are provided only to illustrate the operation of semiconductor products and application examples You are fully responsible for the incorporation of these circuits software and information in the design of your equipment Renesas Electronics assumes no responsibility for any losses incurred by you or third parties arising from the use of these circuits software or information Renesas Electronics has used reasonable care in preparing the information included in this document but Renesas Electronics does not warrant that such information 15 error free Renesas Electronics assumes no liability whatsoever for any damages incurred by you resulting from errors in or omissions from the information included herein Renesas Electronics does not assume any liability for infringement of patents copyrights or other intellectua
15. cement 1 Minimize the placement press in distance 2 Select a nozzle with a small spring load 3 Increase the solder paste viscosity These are effective at achieving good results R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 10 of 21 Mar 25 2015 QFN Mounting Manual 4 Package Placement We recommend that the user look into the package placement conditions used based on the paste materials and package placement equipment used D NO O Printing area 100 NC lt e O Printing area Spring load 60 placement load Placement Load Spring load N 0 2 0 4 Placement Press in Distance mm Note 1 Type 4 Solder particle diameter Type 4 gt Type 5 Figure 4 2 Relationship Between Placement Load and Solder Spreading R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 11 of 21 Mar 25 2015 KENES QFN Mounting Manual 5 Reflow Thermal Resistance 5 Reflow Thermal Resistance 5 1 Storage Prior to Opening Moisture Proof Packing Before opening moisture proof packing semiconductor devices must be stored at a temperature in the range 5 to 35 C and at a humidity under 85 RH Note however that individual products may have product specific stipulations Thus all products must be stored only after verifying the conditions stipulated in the delivery specifications document 5 2 Storage After Opening Moisture Proof Packing After opening moisture proo
16. e information ic name list index sp R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 2 of 21 Mar 25 2015 KENES QFN Mounting Manual 2 Mounting Pads 2 Mounting Pads 2 1 Pad Structure 1 NSMD Type In this structure the solder resist does not come over the edges of the mounting pads 2 SMD Type In this structure the solder resist comes over the edges of the mounting pads It is important to consider the characteristics of the lead morphology when designing printed wiring boards Also it is important to be aware that even if the package code is identical there may be subtle differences in pin dimensions between individual parts Mounting pad Solder resist Mounting pad Solder resist Printed wiring board Printed wiring board Pee eee Pee eee See n tu Te TO nupto Ta np Ta auta a o aa nut sya RI RI RI SMD structure NSMD structure Solder Masked Defined Non Solder Masked Defined Figure 2 1 Pad Structures R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 3 of21 Mar 25 2015 QFN Mounting Manual 2 Mounting Pads 2 2 Mounting Pad Design Parameters The parameters that determine the mounting
17. esas O Recommended temperature range for the solder paste soldering position temperature S Solder manufacturer Q E Above the fusing temperature for the solder and the package s ball metal or lead plating metal lt v Preheating Main heating Time seconds Figure 5 2 Soldering Temperature G pkg lead o board E 0 20 40 60 80 100 120 140 160 180 200 220 Time seconds Figure 5 3 Sample Reflow Temperature Profile for Sn Ag Cu Solder Paste P WQFN32 5x5 0 5 R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 14 of 21 Mar 25 2015 KENES QFN Mounting Manual 6 Cleaning 6 Cleaning Previously a wide variety of cleaning agents have been used in the flux cleaning performed after components are mounted on the printed wiring board However there have been increasing desires for selective use of cleaning agents in consideration of environmental pollution problems and for support of mounting without a cleaning step Since the standoff height of mounted QFN packages 15 comparatively low it 1s difficult to remove flux residues that remain between the QFN package and the mounting board We recommend that users look into the types of solder paste that due not require cleaning or consulting with the solder paste and cleaning agent manufacturers R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 15 of 21 Mar 25 2015 KE
18. f packing semiconductor devices must be stored under the following conditions to prevent moisture absorption by the packages Table5 1 Sample Storage Conditions Wm Cono Rm Humidity Under 70 RH Time 168 hours The time the point the packaging is opened until mounting the last device has completed Note however that individual products may have product specific stipulations Thus all products must be stored only after verifying the conditions stipulated in the delivery specifications documents 5 3 Baking Before soldering perform the baking operation described below 1 Cases When Baking Is Required e Ifthe 30 spot on the indicator card packed with the products has changed to pink when the moisture proof packing was opened e Ifthe stipulated storage condition after opening the moisture proof packing were exceeded 2 Baking Conditions Use the following conditions for baking Note however that some products have individual stipulations and the baking drying processing should be performed after verifying the conditions stipulated in the delivery specifications During baking use trays or other containers with adequate thermal resistance Note that trays that are heat proof will be marker Heat Proof or with their thermal resistance temperature Check this marking before performing this processing Table5 2 Sample Baking Conditions Baking Temperature Baking Time Repeated Baking 125 C 4 to 24 hours N
19. he results of evaluating the effects and influence of the reflow atmosphere This shows that a nitrogen atmosphere can be more effective than air for reflow soldering and also that we can see an effect on pin end surface wetting by soldering the die pad We recommend die pad soldering which has an effect on pin end wetting and nitrogen atmosphere reflow soldering Air Reflow Nitrogen Reflow Figure 7 2 Comparison of Effects and Influence of the Reflow Atmosphere R50ZZ20005EJ0150 Rev 1 50 LEN ESAS Page 17 of21 Mar 25 2015 QFN Mounting Manual 8 On Board Mechanical Stress Test Results 8 On Board Mechanical Stress Test Results After mounting solder may be peeled away by mechanical shock The user should design products and manufacturing processes based on thorough verification of stresses applied during manufacturing such as when cutting boards apart the possibility of accidentally dropping boards and the environment in which the product will be handled in the market since they don t have leads QFN packages mounted on a printed wiring board cannot follow bending of the wiring board and we have identified cases when due to their not being able to follow the wiring board the packages crack when extremely large bending 15 applied to the wiring board We recommend that users look into board mounting layouts that avoid mounting in sections to which large bending forces may be applied Bending depth Evaluati
20. l property rights of third parties by or arising from the use of Renesas Electronics products or technical information described in this document No license express implied or otherwise 15 granted hereby under any patents copyrights or other intellectual property rights of Renesas Electronics or others You should not alter modify copy or otherwise misappropriate any Renesas Electronics product whether in whole or in part Renesas Electronics assumes no responsibility for any losses incurred by you or third parties arising from such alteration modification copy or otherwise misappropriation of Renesas Electronics product Renesas Electronics products are classified according to the following two quality grades Standard and High Quality The recommended applications for each Renesas Electronics product depends on the product s quality grade as indicated below Standard Computers office equipment communications equipment test and measurement equipment audio and visual equipment home electronic appliances machine tools personal electronic equipment and industrial robots etc High Quality Transportation equipment automobiles trains ships etc traffic control systems anti disaster systems anti crime systems and safety equipment etc Renesas Electronics products are neither intended nor authorized for use in products or systems that may pose a direct threat to human life or bodily injury artificial life sup
21. n and reduced weight QFN packages are classified by their formation method into the punching cut and dicing cut types The remainder of this section presents an overview of these packages 1 1 Punching Cut Type anvil singulation This type of QFN package 15 characterized by an individually molded body with punch press excision Since the external leads of the package in which each cavity 15 sealed with mold resin are punched with a die the leads can be made to protrude for extremely short distances from the package periphery Figure 1 1 Package Top Side Figure 1 2 Package Underside Wire bonding Chip Figure 1 3 Basic Structure Figure 1 4 Cross Section View R50ZZ20005EJ0150 Rev 1 50 LENESAS Page 1 of 21 Mar 25 2015 QFN Mounting Manual 1 The QFN Package 1 2 Dicing Cut Type SAW singulation This type of QFN package 15 characterized by the package being formed by cutting with a rotating blade Since multiple packages sealed at the same time are cut apart with a dicing blade rotating blade the ends of the leads and the edge of the package cut surface are coplanar Figure 1 5 Package Top Side Figure 1 6 Package Underside Wire bonding Mold resin Figure 1 7 Basic Structure Figure 1 8 Cross Section View 1 3 Lead Surface Processing Specifications See the Renesas web site for the lead surface processing specifications for each QFN package code http www renesas com products packag
22. o more than 96 hours total 10 to 72 hours No more than 96 hours total R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 12 of 21 Mar 25 2015 KENES QFN Mounting Manual 5 Reflow Thermal Resistance 5 4 Number of Reflow Operations The number of reflow operations should be limited to three or fewer Note however that some products have individual stipulations and the content of the delivery specifications for the products used should be verified Furthermore users should verify that multiple reflow operations will not result in other problems when designing the mounting process After products have been mounted on dual sided boards or by repairs when heating for soldering for reflow or a repeated reflow problems such as solder shorting or solder peeling may occur The following points should be observed when setting mounting conditions e If moisture has been absorbed the warping characteristics of QFN package products and the wiring board itself may change e The user should manage moisture absorption during reflow operations e The use of flux and optimization of the reflow atmosphere should be considered to assure solder coverage when remelting solder The mounting process must be optimized so that the temperatures of the package electrical contacts do not greatly exceed the melting point of the solder Furthermore users should look into setting the temperature to be at or below the melting point of the solder 5 5 Reflow Thermal Re
23. ods Methods in which X ray transmission images are converted to 3D data showing the object s actual shape Methods in which X ray slice images are converted to 3D data showing the object s actual shape 7 1 Overview of the QFN Package Pin End Surface Since like the QFP and other packages the QFN pin end surface is created by cutting processing performed after pin plating QFN packages have a structure in which the pin material without plating 15 exposed In particular in dicing cut type QFN packages since there is no flow around of plating material the exposed surface of the pin material Cu 15 large The following shows the results of studying the wettability of these pin ends Punching Cut Type Dicing Cut Type Pin End Surface Pin End Surface Package Back Surface Pin End Visual Appearance As is the case with QFP and Dicing cut is performed by similar packages the pin ends cutting with a dicer a rotating are cut by punching with a die blade The pin end surface pin The pin end surface pin material is exposed and some material is exposed of the plating material flows around the edges These however are not subject to this management Features of the Machining Figure 7 1 QFN Pin End Surface Overview R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 16 of 21 Mar 25 2015 QFN Mounting Manual 7 Misual Inspection 7 2 Visual Comparison of Air Reflow and Nitrogen Reflow Mounting The table below shows t
24. on method of maximum bending Load from back side center of board To measure depth when package crack occurred Figure 8 1 Evaluation Method of Maximum Figure 8 2 Package Crack Bending Table8 1 Evaluation Results of Maximum Bending Reference BEEN Measurement Span for Bending Max Bending Depth Bending Load 17 18 mm 3 23 kg i R50ZZ0005EJ0150 Rev 1 50 lt 2 AS Page 18 of 21 Mar 25 2015 KENES QFN Mounting Manual 9 On Board Reliability Test Results 9 On Board Reliability Test Results 9 1 Board Mounted Thermal Cycle Test Results punching cut type 6 x 6 mm 0 4 mm pitch The results of an evaluation of the effects of whether or not die pad soldering was used are shown below This testing showed that die pad soldering has an effect on solder connection reliability Table 9 1 Evaluation Specs F t Weibull Plot Test 55 to 125 C 10 minutes dwell t temperature 95 MEI MEER OE ROUEN LAM lili 90 Solder paste Sn Ag Cu without E Pad soldering Err Package P VQFN48 6x6 0 4 Solder paste Sn Ag Cu with E Pad soldering AHU LL L 60 eS o s pan Lead material Cu 3042 FEM EIE m Sot Lead plating Sn Bi mmm Printed wiring Size 50 x 100 x t0 8 mm li board Material FR 4 4 layers surface processing 7 Cu OSP IN Iu k uz aperture 1 6 mm square x 4 0 196 Reflow soldering
25. physical injury and injury or damage caused by fire in the event of the failure of a Renesas Electronics product such as safety design for hardware and software including but not limited to redundancy fire control and malfunction prevention appropriate treatment for aging degradation or any other appropriate measures Because the evaluation of microcomputer software alone 15 very difficult please evaluate the safety of the final products or systems manufactured by you Please contact a Renesas Electronics sales office for details as to environmental matters such as the environmental compatibility of each Renesas Electronics product Please use Renesas Electronics products in compliance with all applicable laws and regulations that regulate the inclusion or use of controlled substances including without limitation the EU RoHS Directive Renesas Electronics assumes no liability for damages or losses occurring as a result of your noncompliance with applicable laws and regulations Renesas Electronics products and technology may not be used for or incorporated into any products or systems whose manufacture use or sale is prohibited under any applicable domestic or foreign laws or regulations You should not use Renesas Electronics products or technology described in this document for any purpose relating to military applications or use by the military including but not limited to the development of weapons of mass destruction When exporting the Renesas
26. port devices or systems surgical implantations etc or may cause serious property damages nuclear reactor control systems military equipment etc You must check the quality grade of each Renesas Electronics product before using it in a particular application You may not use any Renesas Electronics product for any application for which it is not intended Renesas Electronics shall not be in any way liable for any damages or losses incurred by you or third parties arising from the use of any Renesas Electronics product for which the product is not intended by Renesas Electronics You should use the Renesas Electronics products described in this document within the range specified by Renesas Electronics especially with respect to the maximum rating operating supply voltage range movement power voltage range heat radiation characteristics installation and other product characteristics Renesas Electronics shall have no liability for malfunctions or damages arising out of the use of Renesas Electronics products beyond such specified ranges Although Renesas Electronics endeavors to improve the quality and reliability of its products semiconductor products have specific characteristics such as the occurrence of failure at a certain rate and malfunctions under certain use conditions Further Renesas Electronics products are not subject to radiation resistance design Please be sure to implement safety measures to guard them against the possibility of
27. ropic agents Preventing separation of solder powder and flux and droop prevention e Activating agents Metal cleaning e Solvents Forming the paste There are three main types of flux rosin fluxes alloy resin fluxes and water soluble fluxes In addition rosin fluxes are classified into three types by their degree of activation R rosin flux RMA weakly activated flux and RA activated flux Table 3 1 lists their features R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 6 of21 Mar 25 2015 QFN Mounting Manual 3 Solder Paste Printing Table3 1 Flux Types and Features T e 12 aj E 1 7 Au R ROL Type These non activated fluxes are noncorrosive non activated Rosin Rosin Low activity levels Type RMA ROM Type These are mildly activated fluxes and are noncorrosive They Rosin Mildly Activated Rosin Moderate activity have superior solderability compared to the R type fluxes levels Type RA ROH Type These are strongly activated fluxes While they have superior Rosin Activated Rosin High activity levels solderability compared to the R and RMA type fluxes they are strongly corrosive 3 2 Stencils In the stencil design both the pin and the die pad sections must be optimized The user must design the stencil according to the conditions under which it will be used 1 Pin Section The pin sections are 10096 of the mounting pad area Also they must be reduced by a
28. s a variety of lead free metal compositions mainly Sn Ag Cu family compositions are widely used The different lead free alloys are used according to the type of application and the soldering method used Furthermore there is a range of particle sizes in these powders and the particle size affects the printability and other characteristics of the paste Good results can be obtained especially for fine pitch 0 5 mm and under mounting if a fine powder with particle diameter of 40 um or smaller and also with a narrow distribution of particle sizes is used Note however that for finer powders there are concerns that solder balls due to surface oxidation and adverse influence on the wettability may occur Therefore extra care is required when handling solder paste that uses solder powders such as those discussed above Type 3 0 045 mm to 0 020 mm Type 4 0 038 mm to 0 020 mm Type 5 0 025 mm to 0 010 mm Figure 3 1 Visual Appearance of Solder Powders 2 Flux Flux improves solderability in the soldering process in three ways 1 it excludes oxides from components and the pattern surface 2 it prevents re oxidation during soldering and 3 it reduces the surface tension of the melted solder Flux includes four components that assist in soldering tackifiers thixotropic agents solvents and activators These are used for the following purposes e Tackifier resins Component mountability metal cleaning reoxidation prevention e Thixot
29. sistance Although QFN package products have a thermal resistance of 260 C maximum to support lead free solders as stipulated in JEDEC J STD 020D individual products may have a different thermal resistance temperature Contact your Renesas sales representative for details on individual products 260 C Max 255 C N 30s Max 3 C s Max 6 C s Max 211 Cv 150 s 150 C 200 C 60 to 120s Package Surface Temperature C Time seconds Figure 5 1 Reflow thermal Resistance Profile R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 13 of 21 Mar 25 2015 QFN Mounting Manual 5 Reflow Thermal Resistance 5 6 Soldering Temperature The reflow soldering temperature must be managed so that the package body temperature remains under its heat resistance temperature The ideal temperature conditions are those such that the package contacts and pins enter the recommended temperature range for the solder paste used Since the preheating temperature and time and the main soldering temperature and time will differ depending on the composition of the solder used and the characteristics of the flux these must be verified in advance Also note that the soldering atmosphere nitrogen atmosphere is an item that has a large effect and influence on the soldering time and temperature and must be taken into consideration when analyzing the process condition settings Up to the package heat resistance temperature surface temperature Ren
30. ved during package reworking component replacement Therefore we strongly recommend that component reuse be avoided if at all possible Chip capacitor SOP Hot air BGA LN o Mounting board QFN Heated stage Figure 10 1 QFN Reworking Method R50ZZ0005EJ0150 Rev 1 50 LENESAS Page 21 of21 Mar 25 2015 QFN Mounting Manual Publication Date Rev 1 00 Sep 26 2013 Rev 1 50 Mar 25 2015 Published by Renesas Electronics Corporation 44 NE SAS SALES OFFICES Renesas Electronics Corporation http www renesas com Refer to http www renesas com for the latest and detailed information Renesas Electronics America Inc 2801 Scott Boulevard Santa Clara CA 95050 2549 U S A Tel 1 408 588 6000 Fax 1 408 588 6130 Renesas Electronics Canada Limited 9251 Yonge Street Suite 8309 Richmond Hill Ontario Canada LAC 9T3 Tel 1 905 237 2004 Renesas Electronics Europe Limited Dukes Meadow Millboard Road Bourne End Buckinghamshire SL8 5FH U K Tel 44 1628 585 100 Fax 44 1628 585 900 Renesas Electronics Europe GmbH Arcadiastrasse 10 40472 D sseldorf Germany Tel 49 211 6503 0 Fax 49 211 6503 1327 Renesas Electronics China Co Ltd Room 1709 Quantum Plaza No 27 ZhiChunLu Haidian District Beijing 100191 P R China Tel 86 10 8235 1155 Fax 86 10 8235 7679 Renesas Electronics Shanghai Co Ltd Unit 301 Tower A Central Towers 555 Langao Road Putuo District Shanghai
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