AN1902 Freescale Semiconductor / Motorola, AN1902 Datasheet
AN1902
Related parts for AN1902
AN1902 Summary of contents
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... Freescale Semiconductor, Inc. Application Note AN1902/D REV. 2, 03/2002 QUAD FLAT PACK NO-LEAD (QFN) 1.0 PURPOSE This document provides guidelines for Printed Circuit Board (PCB) design and assem- bly. Package performance such as: MSL rating, board level reliability, electrical para- sitic and thermal resistance data are included as reference. ...
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... Freescale Semiconductor, Inc. AN1902/D 3.2 Package Dimensioning Available QFN packages range from 3 9.0 x 9.0mm in size. As the pack- age size shrinks and the lead count increases, the dimensional tolerance and posi- tioning accuracy affect subsequent processes. Special care must be taken when preparing for test, especially in the test contactor cavity design and contactor pin loca- tion ...
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... A solder fillet is expected to form and should be visible on the PCB after the solder reflow process. Figure 3 MAP QFN "E" Version [2]: Left-Bottom View, Right-Tilted to Show Side MOTOROLA For More Information On This Product, Figure 2 General QFN Cross Section & Bottom Views Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Figure 3). 3 ...
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... Freescale Semiconductor, Inc. AN1902/D 3.3.2.2 MAP QFN: “S” Style The “S” style is a Motorola version based on JEDEC MO-220 with an exception in the lead end feature. The lead end is slightly recessed from the package perimeter due to a ½ etched leadframe. No solder fillet is expected after the solder reflow process (See Figure Figure 4 MAP QFN " ...
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... PCB. The clearance around the copper pad and solder mask should be 75µm nominal to account for the registration tolerance of the solder mask. MOTOROLA For More Information On This Product, Figure 6 Motorola MAP Style QFN Process Flow Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 5 ...
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... Freescale Semiconductor, Inc. AN1902/D 4.1.1.2 PCB Thermal Pad Guidelines The QFN package, with its exposed die pad soldered to the PCB, has a good thermal path to the board. The thermal performance of the package is greatly influenced by the PCB design. The PCB thermal pad should be Solder Mask Defined (SMD). The pad area is controlled by the size of the solder mask opening ...
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... Table 1 PCB Specification FR4 4” x 4” 1.0 mm Flash Gold 0.05µm – 0.127µm Non-Solder Mask Defined Pad on Perimeter Lead. Solder Mask Defined Pad on Thermal Pad Figure 9 Land Pattern Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Table 1. Figure 9 and Table ...
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... Freescale Semiconductor, Inc. AN1902/D Version Number of pins A - Pitch (mm Lead pad length (mm Lead pad width (mm Maximum compent lead length (mm) Maximum compent lead width (mm) The PCB terminal pad should be approximately 0.05mm longer than the length of the package lead. The extra 0.05mm should extend towards the center of the package. ...
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... Pitch QFN 0.18mm 0.32mm 0.24mm 0.26mm 0.30mm 0.20mm Figure 11 PCB Pad Dimensions Table 4 provides pad-to-exposed pad spacing for various QFN packages. Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Figure 11). Table 3 pro- 0.65mm Pad Spacing Pitch QFN 0.23mm 0.42mm 0.30mm 0.35mm ...
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... Freescale Semiconductor, Inc. AN1902/D Table 4 Spacing Between Maximum Package Pad and Maximum Exposed Pad QFN Package 32 QFN 0.50mm 32 QFN 0.65mm 48 QFN 0.50mm 44 QFN 0.65mm For general guidelines, the PCB pad should be long enough to accommodate the larg- est package pad. The PCB pad should extend past the exterior package edge for the solder fillet to form ...
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... MOTOROLA For More Information On This Product, illustrates this “scooping” effect. Other reasons for segmenting the Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 11 ...
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... Freescale Semiconductor, Inc. AN1902/D Several different array patterns are being recommended in this section. Smaller QFN package sizes, such as the 3x3mm and 4x4mm, doesn’t require any thermal pad pat- tern on PCB and stencil unless to minimize solder voids. On the larger packages, stencil thermal openings should be segmented in smaller regions. Studies performed for “ ...
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... Too small of a ratio will cause the solder paste to stick on the side wall of the stencil aperture instead of the land of the PCB. MOTOROLA For More Information On This Product, 0.85mm 0.3mm Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 2.0mm 0.55mm 13 ...
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... Freescale Semiconductor, Inc. AN1902/D Version Lead pad width (mm) Lead pad length (mm) Pitch (mm) Thermal pad width (mm) Thermal pad length (mm Aspect ratio Area ratio 4.2.2.2 PCB Land and Aperture Opening for 4x4 QFN Figure 16 (L) Land Pattern on PCB, (R) Stencil Aperture Opening on 4x4mm QFN 14 Table 5 Dimensions of Stencil Aperture ...
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... It is recommended to use a no-clean solder paste. MOTOROLA For More Information On This Product, PCB land 0.69mm Aperture opening PCB Land Component Placement Figure 18 SMT Process Flow Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 0.69mm 0.28mm Stencil Figure 18. Reflow Inspection Soldering 15 ...
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... Freescale Semiconductor, Inc. AN1902/D The spread of solder paste during reflow partially depends upon the solder paste alloy. SnPb solder alloys spread significantly better than the lead-free pastes (ie: SnAgCu, SnAgBiCu, etc.). 5.2.2 Component Placement The QFN package is comparatively small in size. The high lead interconnection and insertion density suggests that precise and accurate placement machines are pre- ferred ...
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... The observed solder wettings are considered acceptable. MOTOROLA For More Information On This Product, Solder balls melt, wetting Flux and wicking reduces begin metal oxide II III I Figure 20 General Solder Reflow Phases Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Solder completely melted Cool down phase, solder solidifies ...
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... Freescale Semiconductor, Inc. AN1902/D 5.2.4.2 X-Ray Inspection X-ray is one way to detect solder shorts underneath the QFN package. X-rays trans- mitted from the X-ray tube are absorbed by the components in proportion to their den- sity. In this case, solder joint having a higher density absorbs most of the X-rays and ...
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... QFN packages. Solder Pad MAP QFN “E” Style MAP QFN “S” Style Figure 23 Micro-Sectioning of Various Styles of QFN Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Molding Compound Thermal Exposed Pad Solder Thermal Pad ...
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... Freescale Semiconductor, Inc. AN1902/D 5.3.1 Package Removal In general, a rework station should have a split light system table for alignment and a hot air reflow system with top and bottom heaters for component removal. To remove the faulty component from the board, hot air is applied from the top and bottom heaters ...
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... Reflow Soldering The replaced component is then soldered to the PCB using a temperature profile sim- ilar to the normal reflow soldering process. MOTOROLA For More Information On This Product, Superimpose QFN on PCB Figure 26 Component Placement Process Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D Figure 26). 21 ...
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... Freescale Semiconductor, Inc. AN1902/D 6.0 MOISTURE SENSITIVITY LEVEL RATING The Moisture Sensitivity Level (MSL) indicates the floor life of the component and its storage conditions after the original container has been opened. The lower the MSL value, the less care is needed to store the components. The QFN MSL reliability is dependent upon the different supplier material set and package size ...
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... Package Engineer to obtain specifics on PCB and stencil design layouts. All experi- ments were performed using similar size test boards. MOTOROLA For More Information On This Product, Table 7 and Table 8 for the different package size, lead count Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 23 ...
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... Freescale Semiconductor, Inc. AN1902/D Table 7 Best Case TFF on QFN, Sorted by Package Size and Lead Count Pkg Size (mm) 5x5 (EP) 5x5 (EP) 5x5 (EP) 5x5 (EP) 7x7 (EP) 7x7 (EP) 7x7 (EP) 7x7 (EP) 7x7 (EP) 7x7 (EP) 8x8 8x8 9x9 (EP) Table 8 Best Case TFF on QFN, Sorted by Pitch, Temp Cycle and Package Size ...
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... Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D are highly dependent upon 8. measures θ board with two signal layers and R help bound the θ ...
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... Freescale Semiconductor, Inc. AN1902/D mance of the QFN package when the board is adhered to a metal housing or heat sink and a complete thermal analysis is done. These thermal resistances help bound the thermal problem under distinct environments. Table 9 generated using Silicon (Si) die. There is an inverse relationship between the body size of the package and the thermal resistances ...
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... Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D 1,2 1 θJA θJMA θJB θJC °C/W °C/W °C/W ° 1.0 74 ...
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... Freescale Semiconductor, Inc. AN1902/D flag size ratio, longer bonding wires may be required for the QFN than for the same device in a leaded package or BGA. In these cases, the RLC performance may be poorer for the QFN package. Therefore, it should not be assumed that the QFN will provide better electrical performance for all devices as the die size and bonding wire length must be considered ...
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... Lead Number Figure 31 48ld TQFP vs. QFN Package Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D TQFP QFN 30. Self-inductance of different die Self Inductance: Leads + Bonding Wire 3. 1.00 Die Size = 5. 5.43 mm 0.50 Die Size = 6 ...
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... Freescale Semiconductor, Inc. AN1902/D The RLC circuit model (See for a package based on the transfer function between the circuit input and output nodes. By using such a methodology, the 3dB cut-off frequency of a package can be predicted. The graph in longest wire of a new device packaged in the 48-lead 7x7mm QFN package. The pre- dicted value for cut-off frequency is 2 ...
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... T. Montes de Oca, T. Koschmieder, B. Joiner, "Impact of Board Variables on the Thermal Performance of a QFN Package”, 2001. MOTOROLA For More Information On This Product, QFN Data Units Mean Std. Dev. mA 24.8 0.39 µA 1.90 0.80 dB 21.6 0.71 µA -39.1 1.26 µA -21.6 0.82 µA -3.57 0.37 µA/dB -0.44 0.01 dB 24.04 1.04 V 0.92 0.04 V 0.49 0.01 MH 16.73 1.23 V 0.50 0.01 MH 16.47 1.21 Quad Flat Pack No-Lead (QFN) Go to: www.freescale.com AN1902/D LQFP Data Delta in Mean Mean Std. Dev. 27.6 0.45 -2.8 2.39 0.74 -0.49 19.7 0.75 1.9 -37.1 1.39 -2 -20.3 0.91 -1.3 -4.38 0.53 0.81 -0.41 0.02 -0.03 18.93 1.51 5.11 0.94 0.03 -0.02 0.48 0.01 0.01 16.73 0.45 0 0.49 0.01 0.01 16.47 0. ...
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... Motorola and the Stylized M Logo are registered in the U.S. Patent and Trademark Office. digital dna is a trademark of Motorola, Inc. All other product or service names are the property of their respective owners. Motorola, Inc Equal Opportunity/Affirmative Action Employer. © Motorola, Inc. 2001 AN1902/D Go to: www.freescale.com ...