A soldering pad for 0402 capacitor package under BGA

Abstract

The invention relates to a pad for packaging 0402 capacitors under BGA. The pad is in the shape of an arc, has a simple structure, increases the effective space for layout and wiring between the pad and a via hole, increases the internal safety gap, enables more resistor and capacitor components to be placed in the limited space under the BGA, can ensure the filtering effect and current carrying capacity of the power PIN pin under the BGA, avoids the influence of the filtering and heat dissipation effect of the BGA by increasing the 0402 resistor and capacitor components by forcibly deleting the via hole in the prior art, and increases the effective welding area of ​​the pad, which is helpful to improve the reliability of welding. The optimization of the pad outlet mode can improve the impedance accuracy and signal integrity.

Description

Technical Field

[0001] The invention relates to the field of PCB packaging, and in particular to a soldering pad used for 0402 capacitor packaging under BGA. Background Art

[0002] As electronic products become smaller and smaller and more and more functional, and the logic and system clock frequencies in communication systems continue to increase, the current load, filtering, layout and wiring, and welding issues in the BGA packaging process of high-density PCBs have brought considerable challenges. In traditional PCB design, the 0402 capacitor packaging under BGA uses rectangular pads to punch holes to other layers to lead out power and signal lines. Due to the limitations of space and structure in the BGA, some vias usually need to be deleted to place the 0402 package, which has a certain impact on the current, filtering and signal integrity of the circuit. Summary of the invention

[0003] The purpose of the present invention is to provide a new pad for 0402 capacitor package under BGA to solve the technical problems existing in the prior art. The shape of the new pad is different from that of the pad in the prior art. The present invention is realized by the following technical scheme: a new pad for 0402 package under BGA, the package pad includes two symmetrically arranged welding areas and solder resist areas, the welding area is a water drop-shaped structure, the solder resist area is a water drop-shaped structure coaxial with the welding area, the larger arc ends of the two welding areas are arranged adjacently, and the other end of the welding area is provided with concave arcs on both sides, and the area of ​​the solder resist area is larger than the area of ​​the welding area. The periphery of the welding area and the solder resist area is surrounded by a steel mesh.

[0004] Furthermore, the axial distance between the two welding areas is 1.02 mm.

[0005] Furthermore, the maximum longitudinal length of the welding area is not less than 0.51 mm, and the maximum transverse length is not less than 0.64 mm.

[0006] Preferably, the maximum longitudinal length of the welding area is 0.72 mm, the minimum longitudinal length is 0.3 mm, and the maximum transverse length is 0.72 mm. The steel mesh is a rounded rectangle with a longitudinal width of 1.06 mm, a transverse length of 2.53 mm, and four corners are arcs with a radius of 0.32 mm.

[0007] Furthermore, a capacitor silk screen is provided between the two package pads, and the outer frames of the two capacitor silk screens are consistent with the standard 0402 package. The steel mesh is not completely closed and a gap is formed in the horizontal direction, the gap is directly opposite to the capacitor silk screen, and the horizontal width of the gap is not greater than the axial distance between the two welding areas.

[0008] The size of the novel solder pad provided by the present invention is larger than that of the existing 0402 package solder pad, and the size of the water droplet-shaped soldering area of ​​the novel solder pad can be fine-tuned to meet layout and wiring requirements under different BGA and PIN spacings.

[0009] The novel pad provided by the present invention is used to package a 0402 capacitor under BGA, each power pin of the BGA chip is connected to the filter capacitor on the back through a signal via, and the pad is used to mount the filter capacitor, and is characterized in that: the pad can accommodate 6 vias. Due to the distribution adjustment of the power supply, ground and signal under the BGA, the number of corresponding vias on the novel pad is not fixed to 6, and the number of vias can be reduced while meeting the PCB design requirements.

[0010] The present invention provides a pad for 0402 capacitor packaging under BGA, which has the following beneficial effects:

[0011] 1. The new pad structure can ensure that each power pin in the BGA has a filter capacitor, achieving an ideal capacitor filtering effect;

[0012] 2. The space between the via and the pad is increased, which can ensure the layout and wiring space of the capacitor, increase its safety spacing, and improve the production yield;

[0013] 3. It avoids the existing BGA wiring that relies on deleting the BGA internal vias to increase the 0402 filter capacitor, which affects the BGA heat dissipation effect and power supply load;

[0014] 4. The optimization of the arc extension of the new pad outlet can avoid the change of instantaneous impedance caused by the change of line width, which affects the integrity of the signal;

[0015] 5. Increase the effective welding area to ensure the reliability of subsequent welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings further illustrate the present invention, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention.

[0017] Figure 1 It is a schematic diagram of the structural shape of the existing 0402 capacitor pad.

[0018] Figure 2 Schematic diagram of the structure of a 0402 capacitor pad according to an embodiment of the present invention.

[0019] Figure 3 A schematic diagram of a BGA package chip using a 0402 capacitor pad provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0021] like Figure 1 As shown in the figure, the existing pad 2 used for 0402 capacitor package under BGA includes two symmetrically arranged conventional steel meshes 23, a conventional capacitor silk screen 24, a conventional welding area 21 and a conventional solder resist area 22. The shape of the existing pad 2 is rectangular, the size of the existing pad 2 is 2.03mm×0.76mm, and the center spacing of the existing pad 2 is 1.02mm. Since the existing pad 2 is rectangular, the signal line leading out from the pad will cause an instantaneous impedance jump, which will have some impact on the integrity of the signal when the signal rate is relatively high.

[0022] like Figure 2 As shown, the present embodiment provides a new type of pad 1 for 0402 capacitor package under BGA, including symmetrically arranged capacitor silk screen 14, welding area 11 and solder resist area 12, the welding area 11 and solder resist area 12 are of the same water drop type structure and coaxial, the area of ​​solder resist area 12 is larger than the area of ​​welding area 11, and the welding area 11 is provided with a first concave arc 111, a second concave arc 112, a third concave arc 113 and a fourth concave arc 114. The periphery of welding area 11 and solder resist area 12 is surrounded by steel mesh 13. The axial distance between the two welding areas is 1.02mm. The maximum longitudinal length of welding area 11 is 0.72mm, the minimum longitudinal length is 0.3mm, and the maximum transverse length is 0.72mm. Steel mesh 13 is a rounded rectangle with a longitudinal width of 1.06mm, a transverse length of 2.53mm, and four corners are arcs with a radius of 0.32mm. The steel mesh 13 is not completely closed and has a gap formed in the horizontal direction, the gap is opposite to the capacitor screen printing 14, and the horizontal width of the gap is 0.5 mm. The new pad 1 can accommodate 6 vias 3, and the 6 vias 3 are symmetrically arranged. Since four concave arcs are arranged on the welding area 11, the space for accommodating the vias 3 is increased compared with the existing pad 2.

[0023] The structure of the novel pad 1 increases the space between the pad and the via hole 3, ensures the wiring space of the capacitor component, increases the safety spacing, and increases the number of resistor and capacitor components, ensuring that each power PIN corner has a filter capacitor without affecting the original wiring space, avoiding the defect of increasing the capacitor component to achieve the filtering effect by forcibly deleting the via hole in the traditional method, and affecting the heat dissipation effect of the BGA, thereby ensuring the current carrying capacity of the power supply; at the same time, it is set as a welding area and a solder mask area, so that during the later assembly welding, the effective welding area is ensured, and the reliability of the welding is ensured.

[0024] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0025] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A pad for 0402 capacitor package under BGA, the package pad comprising two symmetrically arranged welding areas and a solder resist area, characterized in that: The welding area is a teardrop-shaped structure, the solder resist area is a teardrop-shaped structure coaxial with the welding area, the larger arc ends of the two welding areas are arranged adjacent to each other, and concave arcs are arranged on both sides of the other end of the welding area, and the area of ​​the solder resist area is larger than the area of ​​the welding area; The peripheries of the welding area and the solder resist area are surrounded by a steel mesh; The axial distance between the two welding areas is 1.02 mm; The maximum longitudinal length of the welding area is not less than 0.51 mm, and the maximum transverse length is not less than 0.64 mm; The maximum longitudinal length of the welding area is 0.72 mm, the minimum longitudinal length is 0.3 mm, and the maximum transverse length is 0.72 mm; The steel mesh is a rounded rectangle with a longitudinal width of 1.06 mm and a transverse length of 2.53 mm, and the four corners are arcs with a radius of 0.32 mm; A capacitor silk screen is provided between the two packaging pads; The steel mesh is not completely closed and has a gap formed in the transverse direction, the gap is directly opposite to the capacitor screen printing, and the transverse width of the gap is not greater than the axial distance between the two welding areas; The pad can accommodate 6 vias.

2. The pad according to claim 1 is used to package 0402 capacitors under BGA, each power pin of the BGA chip is connected to the filter capacitor on the back through a signal via, and the pad is used to mount the filter capacitor, characterized in that: The pad can accommodate 6 vias.

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