CN211429634U

CN211429634U - Pad structure for QFN (quad Flat No-lead) packaging element

Info

Publication number: CN211429634U
Application number: CN202020320613.4U
Authority: CN
Inventors: 李主坤
Original assignee: Marelli Automotive Electronics Guangzhou Co Ltd
Current assignee: Marelli Automotive Electronics Guangzhou Co Ltd
Priority date: 2020-03-16
Filing date: 2020-03-16
Publication date: 2020-09-04
Anticipated expiration: 2030-03-16

Abstract

A pad structure for QFN package element is prepared as setting at least one transverse channel and one longitudinal channel on pad, forming no metal layer and solder mask at position of transverse channel and longitudinal channel and exposing PCB substrate completely.

Description

Pad structure for QFN (quad Flat No-lead) packaging element

Technical Field

The utility model relates to a to QFN (Quad Flat No Lead, four sides do not have pin Flat package) packaging element's pad structure.

Background

Printed circuit board assemblies, which are supports for electronic components, are currently in widespread use in a variety of fields. The modularization, integration and miniaturization of specific circuit functions are more and more common, which leads to the continuous improvement of the heat density of components and assemblies, and researches show that the failure of most electronic components in electronic equipment is poor in design, and the heat dissipation design is a difficult problem to be faced by each equipment.

At present, QFN packages are rapidly increasing in device applications due to their superior properties of lightness, smallness, thinness, low self-inductance, high efficiency heat dissipation, etc., components of QFN packages have pads on their bottoms that are horizontal to the bottom surface, and during operation, heat generated by the components of QFN packages is mainly conducted to a printed circuit board through the pads, so that the temperature of the components of QFN packages is reduced. However, when the pads are soldered by the smt (surface mount technology) surface mount technology, the solder paste contains air, water, flux and other components, which causes the pads to easily generate bubbles, voids and other problems, and these problems directly affect the heat dissipation performance and efficiency of the components of the QFN package, thereby increasing the risk of failure and even fire of the devices due to overheating during the use process.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a to QFN packaging element's pad structure, avoid the pad bubble to appear when the welding and defect such as cavity.

A pad structure to QFN packaged component, including PCB base plate and setting up the pad at PCB base plate surface, be provided with at least a transverse channel and a vertical passageway on the pad and separate into a plurality of independent little pads with the pad, transverse channel and vertical passageway department expose the PCB base plate completely.

A pad structure to QFN packaged component, owing to be provided with an at least transverse channel and a vertical passageway on the pad, and transverse channel and vertical passageway department do not have metal level and solder mask, expose the PCB base plate completely, therefore, when the welding, not only can discharge horizontal channel and vertical passageway department with air and vapor that produces when the tin cream melts effectively, can also bin up the scaling powder of discharging when the tin cream melts in transverse channel department and vertical passageway department, bubble and defect such as cavity that produce when having reduced the welding by a wide margin, the reliability of solder joint has been improved, the ground connection function has not only been realized, heat dispersion and efficiency have still been showing and have been improved.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a second embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a third embodiment of the present invention.

Fig. 4 is a bottom view of fig. 2.

Detailed Description

A pad structure for a QFN package component is disclosed, as shown in FIGS. 1 to 4, and comprises a PCB substrate 1 and a pad arranged on the outer surface of the PCB substrate 1, wherein at least one transverse channel 2 and one longitudinal channel 3 are arranged on the pad to divide the pad into a plurality of independent small pads 4, and the transverse channel 2 and the longitudinal channel 3 completely expose the PCB substrate 1. One transverse channel 2 and one longitudinal channel 3 are arranged, and the transverse channel 2 and the longitudinal channel 3 are crossed to form a cross shape as shown in figure 1; the number of the transverse channels 2 is two, the number of the longitudinal channels 3 is two, and the transverse channels 2 and the longitudinal channels 3 are crossed to form a # -shaped structure as shown in figure 2; the number of the transverse channels 2 is three, the number of the longitudinal channels 3 is three, and the transverse channels 2 and the longitudinal channels 3 are arranged in a crossed mode as shown in figure 3.

The width A of the transverse channel 2 and the width B of the longitudinal channel 3 are both 0.2 mm-5 mm, such as 0.2mm, 0.5mm, 1mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2mm, 2.3 mm, 2.6 mm, 2.9 mm, 3mm, 3.4 mm, 3.8mm, 4mm, 4.1 mm, 4.3 mm, 4.6 mm, 4.8 mm or 5 mm; the length D of the transverse channel 2 and the length E of the longitudinal channel 3 are both 1 mm-10 mm, such as 1mm, 1.5 mm, 2mm, 2.5 mm, 3mm, 3.5 mm, 4mm, 4.5 mm, 5mm, 5.5 mm, 6 mm, 6.5 mm, 7mm, 7.5 mm, 8mm, 8.5 mm, 9mm, 9.5 mm or 10 mm.

The small bonding pad 4 is circular, rectangular, square or irregular polygon, and the small bonding pads 4 in fig. 1 to 3 are all square.

The circumference of the small pad 4 is 1 mm-50 mm, such as 1mm, 5mm, 10mm, 13mm, 17mm, 20mm, 24mm, 28mm, 30mm, 32mm, 35mm, 39mm, 40mm, 45mm, 48mm or 50 mm.

The depth H of the longitudinal channels 3 and the transverse channels 2 is 11 μm to 110 μm, such as 11 μm, 15 μm, 17 μm, 20 μm, 23 μm, 26 μm, 28 μm, 30 μm, 33 μm, 35 μm, 37 μm, 39 μm, 40 μm, 42 μm, 45 μm, 47 μm, 49 μm, 50 μm, 51 μm, 54 μm, 57 μm, 59 μm, 60 μm, 62 μm, 66 μm, 68 μm, 70 μm, 73 μm, 75 μm, 79 μm, 80 μm, 81 μm, 83 μm, 86 μm, 87 μm, 90 μm, 93 μm, 95 μm, 97 μm, 99 μm, 100 μm, 102 μm, 105 μm, 107 μm, 109 μm, or 110 μm. At the longitudinal channels 3 and the lateral channels 2 are exposed PCB substrate areas without solder resist.

In conclusion, by the aid of the pad structure, defects such as bubbles and cavities generated during welding can be greatly reduced, reliability of welding spots is improved, a grounding function is achieved, and heat dissipation performance and efficiency are remarkably improved.

Claims

1. A pad structure for QFN packaging element comprises a PCB substrate (1) and a pad arranged on the outer surface of the PCB substrate (1), and is characterized in that: at least one transverse channel (2) and one longitudinal channel (3) are arranged on the bonding pad to divide the bonding pad into a plurality of independent small bonding pads (4), and the PCB substrate (1) is completely exposed at the positions of the transverse channel (2) and the longitudinal channel (3).

2. A pad structure for QFN package components as claimed in claim 1, wherein: the width A of the transverse channel (2) and the width B of the longitudinal channel (3) are both 0.2 mm-5 mm.

3. A pad structure for QFN package components as claimed in claim 2, wherein: the length D of the transverse channel (2) and the length E of the longitudinal channel (3) are both 1 mm-10 mm.

4. A pad structure for QFN package components according to any of claims 1-3, wherein: the small bonding pad (4) is in a shape of a circle, a rectangle, a square or an irregular polygon.

5. A bonding pad structure for QFN package component as claimed in claim 4, wherein: the circumference of the small bonding pad (4) is 1 mm-50 mm.

6. A bonding pad structure for QFN package component as claimed in claim 5, wherein: the depth H of the longitudinal channel (3) and the transverse channel (2) is 11-110 mu m.