SLUA271C June   2002  – December 2023 ADS1013 , ADS1014 , ADS1015 , ADS1018 , ADS1112 , ADS1113 , ADS1114 , ADS1115 , ADS1118 , ADS1120 , ADS1148 , ADS114S06 , ADS114S06B , ADS114S08 , ADS114S08B , ADS1158 , ADS1191 , ADS1192 , ADS1203 , ADS1204 , ADS1205 , ADS1220 , ADS1225 , ADS1226 , ADS124S06 , ADS124S08 , ADS1257 , ADS1258 , ADS1261 , ADS1283 , ADS1287 , ADS1287D , ADS1291 , ADS1292 , ADS1292R , ADS1293 , ADS6222 , ADS6224 , ADS6242 , ADS6243 , ADS6244 , ADS6245 , ADS6422 , ADS6423 , ADS6424 , ADS6425 , ADS6442 , ADS6443 , ADS6444 , BQ24010 , BQ24012 , BQ24013 , BQ24020 , BQ24022 , BQ24023 , CC2560 , CC2564C , CSD13202Q2 , CSD15571Q2 , CSD16301Q2 , CSD16321Q5 , CSD16322Q5 , CSD16323Q3 , CSD16325Q5 , CSD16327Q3 , CSD16340Q3 , CSD16342Q5A , CSD16401Q5 , CSD16403Q5A , CSD16404Q5A , CSD16406Q3 , CSD16407Q5 , CSD16408Q5 , CSD16409Q3 , CSD16410Q5A , CSD16411Q3 , CSD16412Q5A , CSD16413Q5A , CSD16414Q5 , CSD16415Q5 , CSD16556Q5B , CSD16570Q5B , CSD17301Q5A , CSD17302Q5A , CSD17303Q5 , CSD17304Q3 , CSD17305Q5A , CSD17306Q5A , CSD17307Q5A , CSD17308Q3 , CSD17309Q3 , CSD17310Q5A , CSD17311Q5 , CSD17312Q5 , CSD17313Q2 , CSD17318Q2 , CSD17322Q5A , CSD17327Q5A , CSD17501Q5A , CSD17505Q5A , CSD17506Q5A , CSD17507Q5A , CSD17510Q5A , CSD17522Q5A , CSD17527Q5A , CSD17551Q3A , CSD17551Q5A , CSD17552Q3A , CSD17552Q5A , CSD17553Q5A , CSD17555Q5A , CSD17556Q5B , CSD17559Q5 , CSD17570Q5B , CSD17571Q2 , CSD17573Q5B , CSD17575Q3 , CSD17576Q5B , CSD17577Q3A , CSD17577Q5A , CSD17578Q3A , CSD17578Q5A , CSD17579Q3A , CSD17579Q5A , CSD17581Q3A , CSD17581Q5A , CSD18501Q5A , CSD18502Q5B , CSD18503Q5A , CSD18504Q5A , CSD18509Q5B , CSD18510Q5B , CSD18511Q5A , CSD18512Q5B , CSD18513Q5A , CSD18514Q5A , CSD18531Q5A , CSD18532NQ5B , CSD18532Q5B , CSD18533Q5A , CSD18534Q5A , CSD18537NQ5A , CSD18540Q5B , CSD18543Q3A , CSD18563Q5A , CSD19502Q5B , CSD19531Q5A , CSD19532Q5B , CSD19533Q5A , CSD19534Q5A , CSD19537Q3 , CSD19538Q2 , CSD19538Q3A , CSD25310Q2 , CSD25402Q3A , CSD25404Q3 , CSD85301Q2 , CSD85312Q3E , CSD86330Q3D , CSD86336Q3D , CSD86350Q5D , CSD86356Q5D , CSD86360Q5D , CSD87312Q3E , CSD87313DMS , CSD87330Q3D , CSD87331Q3D , CSD87333Q3D , CSD87334Q3D , CSD87335Q3D , CSD87350Q5D , CSD87351Q5D , CSD87351ZQ5D , CSD87352Q5D , CSD87353Q5D , CSD87355Q5D , CSD87502Q2 , CSD87503Q3E , CSD88584Q5DC , CSD88599Q5DC , DAC3482 , DAC3484 , LMR10510 , LMR10515 , LMR10520 , LMR10530 , MSC1202Y2 , MSC1202Y3 , MSP430F1122 , MSP430F1132 , MSP430F122 , MSP430F1222 , MSP430F123 , MSP430F1232 , MSP430F2001 , MSP430F2002 , MSP430F2003 , MSP430F2011 , MSP430F2012 , MSP430F2013 , MSP430F2013-EP , MSP430F2112 , MSP430F2122 , MSP430F2132 , MSP430FR5969 , MSP430G2001 , MSP430G2101 , MSP430G2102 , MSP430G2111 , MSP430G2112 , MSP430G2121 , MSP430G2131 , MSP430G2132 , MSP430G2152 , MSP430G2201 , MSP430G2201-Q1 , MSP430G2211 , MSP430G2212 , MSP430G2221 , MSP430G2231 , MSP430G2231-Q1 , MSP430G2232 , MSP430G2252 , MSP430G2302 , MSP430G2312 , MSP430G2332 , MSP430G2352 , MSP430G2402 , MSP430G2432 , MSP430G2452 , TLA2021 , TLA2022 , TLA2024 , TLV62065 , TLV62080 , TLV62085 , TLV62090 , TLV62130 , TLV62130A , TLV62150 , TLV62150A , TPS60150 , TPS60151 , TPS61020 , TPS61021A , TPS61024 , TPS61025 , TPS61026 , TPS61027 , TPS61028 , TPS61029 , TPS61029-Q1 , TPS61030 , TPS61031 , TPS61032 , TPS61042 , TPS61045 , TPS61086 , TPS61087 , TPS61087-Q1 , TPS61088 , TPS61089 , TPS61090 , TPS61091 , TPS61092 , TPS61093 , TPS61093-Q1 , TPS61100 , TPS61107 , TPS61120 , TPS61130 , TPS61170 , TPS61170-Q1 , TPS61200 , TPS61201 , TPS61202 , TPS61240 , TPS61240-Q1 , TPS61251 , TPS61252 , TPS61260 , TPS61261 , TPS61291 , TPS62020 , TPS62021 , TPS62026 , TPS62040 , TPS62042 , TPS62043 , TPS62044 , TPS62046 , TPS62060 , TPS62061 , TPS62063 , TPS62065 , TPS62067 , TPS62080 , TPS62080A , TPS62081 , TPS62082 , TPS62085 , TPS62086 , TPS62087 , TPS62090 , TPS62090-Q1 , TPS62091 , TPS62092 , TPS62093 , TPS62095 , TPS62097 , TPS62097-Q1 , TPS62110 , TPS62110-EP , TPS62110-Q1 , TPS62111 , TPS62111-EP , TPS62112 , TPS62112-EP , TPS62113 , TPS62122 , TPS62125 , TPS62130 , TPS62130A , TPS62131 , TPS62132 , TPS62133 , TPS62134A , TPS62134B , TPS62134C , TPS62134D , TPS62135 , TPS62136 , TPS62140 , TPS62141 , TPS62142 , TPS62143 , TPS62150 , TPS62150A , TPS62151 , TPS62152 , TPS62153 , TPS62160 , TPS62161 , TPS62162 , TPS62163 , TPS62170 , TPS62171 , TPS62172 , TPS62173 , TPS62175 , TPS62177 , TPS62230 , TPS62231-Q1 , TPS622314-Q1 , TPS62240 , TPS62242 , TPS62243 , TPS62250 , TPS62260 , TPS62260-Q1 , TPS62261 , TPS62261-Q1 , TPS62262 , TPS62262-Q1 , TPS62263 , TPS62263-Q1 , TPS62270 , TPS62272 , TPS62273 , TPS62290 , TPS62290-Q1 , TPS62291 , TPS62293 , TPS62293-Q1 , TPS62300 , TPS62301 , TPS62302 , TPS62303 , TPS62304 , TPS62305 , TPS62320 , TPS62321 , TPS62352 , TPS62355 , TPS62400 , TPS62400-Q1 , TPS62401 , TPS62402 , TPS62403 , TPS62404 , TPS62404-Q1 , TPS62406-Q1 , TPS62407-Q1 , TPS62410 , TPS62410-Q1 , TPS62420 , TPS62420-Q1 , TPS62421 , TPS62422-Q1 , TPS62423-Q1 , TPS62424-Q1 , TPS62510 , TPS62560 , TPS62562 , TPS62590 , TPS62590-Q1 , TPS62730 , TPS62732 , TPS62733 , TPS62740 , TPS62750 , TPS62751 , TPS62821 , TPS62822 , TPS62823 , TPS62825 , TPS62826 , TPS62840 , TPS62870 , TPS62870-Q1 , TPS62871 , TPS62871-Q1 , TPS62872 , TPS62872-Q1 , TPS62873 , TPS62873-Q1 , TPS62874-Q1 , TPS62875-Q1 , TPS62876-Q1 , TPS62877-Q1 , TPS63000 , TPS63000-Q1 , TPS63001 , TPS63002 , TPS63020 , TPS63021 , TPS63030 , TPS63031 , TPS63050 , TPS63051 , TPS63060 , TPS63061 , TPS63070 , TPS63700 , TPS63710 , TPS84620 , TPSM82810 , TPSM82813 , TPSM82816 , TPSM82821 , TPSM82822 , TPSM82864A , TPSM82866A , TPSM82866C , TPSM8287A06 , TPSM8287A10 , TPSM8287A12 , TPSM8287A15 , TUSB7320 , TUSB7340 , TUSB8040A , TUSB8040A1

 

  1.   1
  2.   QFN and SON PCB Attachment
  3.   Trademarks
  4. 1Texas Instruments Quad Flatpack No Leads and Small-Outline No Leads
    1. 1.1 Introduction
  5. 2Manufacturing Considerations
    1. 2.1 SMT Process
  6. 3Printed Circuit Board (PCB) Design Guidelines
    1. 3.1 Land Pad Styles
    2. 3.2 Land Pad Design
    3. 3.3 Lead Finger Pad PCB Design
    4. 3.4 Exposed Pad PCB Design
      1. 3.4.1 Thermal Pad Via Design
    5. 3.5 Solder Mask
    6. 3.6 Surface Finishes
    7. 3.7 Board Layout Considerations
  7. 4Solder Paste Screen Printing Process
    1. 4.1 Solder Paste
    2. 4.2 Solder Stencils
    3. 4.3 Lead Finger Stencil Design
    4. 4.4 Exposed-Pad Stencil Design
  8. 5Package to Board Assembly Process
    1. 5.1 Placement and Alignment
    2. 5.2 Solder Reflow
    3. 5.3 PCB Cleaning
    4. 5.4 Inspection
  9. 6Rework Guidelines (Hot Gas Convection and Manual)
    1. 6.1 Compound Removal
    2. 6.2 Site Redress
    3. 6.3 Component Replacement and Reflow
    4. 6.4 Manual Rework Considerations
  10. 7Revision History

6.3 Component Replacement and Reflow

The first step before replacement is to apply solder paste either to the board or directly to the component. Depending on the application, one of these two methods can be more advantageous, due to factors such as board density and ease of access to the rework site. Evaluate which method is best on a case-by-case basis. Both methods require the use of a mini stencil. Figure 6-1 shows the steps to screen print solder directly onto the component. The solder paste is applied to the part using a fixture courtesy of Photo Stencil.

A component insertion tool ensures proper registration of lightweight QFNs and SONs onto the printed circuit board. In addition, the insertion tool eliminates manual handling of the component, which can deposit unwanted skin oil on the component pads.

Optical systems used for alignment consist of a beam-splitting prism combined with an inspection microscope or video camera fitted with a zoom lens. This optical system allows the operator to see a magnified image of the bottom side of the QFN and SON superimposed over the corresponding PCB land pattern.

Alignment and placement of the QFN and SON must be accurate to within 0,1 mm. When the QFN and SON is correctly aligned, the X-Y table is locked to prevent further movement. The nozzle (Figure 6-2) is lowered until it lightly contacts the board. The nozzle vacuum is automatically deactivated and the thermal reflow cycle begins. PC-based software provides the process control necessary to ensure repeatable results. Once the cool-down stage is complete, the nozzle is raised and the assembly is removed for inspection.

Figure 6-1 shows generic guidelines to remove QFN packages assembled on a 0.056-in FR4 board. It is recommended to modify heating profiles for different board thicknesses and equipment used. Parts must not exceed the peak temperature as listed on the MSL label. Parts and boards must be baked out before rework to reduce the risk of delamination.

GUID-B4F7BB52-F25D-47A6-A8C4-16829949DE20-low.gifFigure 6-1 Example Mini Stencil
GUID-DB512E7E-56EE-4E6E-AC8B-8B7E80D1C605-low.gifFigure 6-2 Example Hot Gas Convection Nozzle
Table 6-2 Pb-Free Solder Component Placement
1.Apply solder paste to component or board using mini-screen printing tool (see Figure 6-4).
2.Align device over pads.
3.Place device on board. Take care to prevent overtravel during placement, which can damage the part or vacuum tip.
4.Raise nozzle 0.050-in
5.Preheat board to 90°C, nozzle warming up 20% air flow, 125°C.
6.Soak stage: 20% air flow, 225°C, 90 s
7.Ramp stage: 20% air flow, 335°C, 30 s
8.Reflow stage: 25% air flow, 370°C, 65 s
9.Cool down stage: 40% air flow, 25°C, 50 s