BGA circuit board structure with 0.4 mm outer layer

Abstract

The utility model provides a 0.4 mm outer layer BGA circuit board structure. The 0.4 mm outer layer BGA circuit board structure comprises a circuit board; the first bonding pad is arranged at the top of the circuit board; the first bonding pad is arranged at the top of the circuit board, the second bonding pad is arranged at the top of the circuit board, through holes are formed in the second bonding pad and the circuit board, annular grooves are formed in the top of the first bonding pad and the top of the second bonding pad, and circular grooves are formed in the top of the first bonding pad and the top of the second bonding pad. According to the 0.4 mm outer layer BGA circuit board structure provided by the utility model, through mutual cooperation of the first bonding pad, the second bonding pad, the through hole and other structures, a lead is led out from each bonding pad in a 9-grid array with the minimum number of 3 * 3 under the condition that the bonding pads are prevented from being reduced, so that the connection strength between each bonding pad and each lead is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of BGA circuit boards, in particular to a 0.4mm outer layer BGA circuit board structure. Background Technique

[0002] PCB, also known as printed circuit board, is an important electronic component, a support for electronic components, and a carrier for electrical connection of electronic components. It includes at least a wiring layer, a shielding layer, and a dielectric layer. The wiring layer includes signal lines and BGA (Ball Grid Array) areas and non-BGA areas connected to the signal lines. In printed circuit boards, with the development of electronic technology towards high density, small size, etc., especially in the field of artificial intelligence (AI).

[0003] The circuit of the pad array of traditional BGA packaging passes through two differential lines. The pitch changes from the hole center pitch of 1mm to the pitch of 0.8mm. The DDR design generally reduces from the pitch of 0.6mm to 0.4mm. Due to the current PCB hardware, equipment, manufacturing process, technology, chemical resolution, the PCB line width, and the resolution of the minimum working draft of the circuit are generally above 2.5 mil. When the pitch is 0.4mm, the equivalent center-to-center distance of the pads is 15.75 mil. In PCB processing, the pads are generally 10 mil to meet the SMT mounting size specifications. Considering the center-to-center distance of 15.75 mil between two round pads with a diameter of 10 mil, the gap between the pads is only 5.75 mil. Designed according to the minimum circuit of 2.5 mil, the distance between the circuit and the pad on one side is only 1.125 mil, which cannot meet the ability of the minimum resolution of the PCB. In this case, for the minimum 3x3 nine-grid array, the circuit of the center pad cannot be led out through the same layer of surface leads.

[0004] Therefore, it is necessary to provide a 0.4mm outer layer BGA circuit board structure to solve the above technical problems. Content of the Utility Model

[0005] The utility model provides a 0.4mm outer layer BGA circuit board structure, which solves the problem that the circuit of the center pad of the minimum 3x3 nine-grid array cannot be led out through the same layer of surface leads.

[0006] To solve the above technical problems, a 0.4mm outer layer BGA circuit board structure provided by the utility model includes:

[0007] A circuit board;

[0008] A first pad, which is arranged on the top of the circuit board;

[0009] The second pad is disposed on the top of the circuit board, and through holes are formed in both the interior of the second pad and the interior of the circuit board.

[0010] Preferably, there are eight first pads and one second pad.

[0011] Preferably, the diameter of the first pad is 10 mil, the diameter of the second pad is 16 mil, and the diameter of the through hole is 8 mil.

[0012] Preferably, the distance from the center of the second pad to the centers of the four first pads around it is 15.75 mil.

[0013] Preferably, the first pads and the second pad are arranged on the top of the circuit board in a 3-row by 3-column form.

[0014] Preferably, annular grooves are provided on the tops of both the first pad and the second pad.

[0015] Preferably, circular grooves are provided on the tops of both the first pad and the second pad.

[0016] Compared with the related art, a 0.4mm outer layer BGA circuit board structure provided by the present utility model has the following beneficial effects:

[0017] The present utility model provides a 0.4mm outer layer BGA circuit board structure. Through the cooperation of structures such as the first pad, the second pad, and the through hole, each pad in the minimum 3 by 3 nine-square array can have a lead wire led out without reducing the size of the pad, thereby ensuring the connection strength between each pad and each lead wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a first embodiment of a 0.4mm outer layer BGA circuit board structure provided by the present utility model;

[0019] Figure 2 is Figure 1 the schematic diagram after compensation shown in;

[0020] Figure 3 is Figure 1 the schematic three-dimensional structure diagram shown in;

[0021] Figure 4 is a schematic structural diagram of a second embodiment of a 0.4mm outer layer BGA circuit board structure provided by the present utility model;

[0022] Figure 5Schematic diagram of the third embodiment of a 0.4mm outer layer BGA circuit board structure provided by the present utility model.

[0023] Reference numerals in the figure: 1, circuit board; 2, first pad; 3, second pad; 31, through hole; 4, annular groove; 5, circular groove. Detailed implementation manners

[0024] The present utility model will be further described below with reference to the accompanying drawings and embodiments.

[0025] First embodiment

[0026] Please refer to Figure 1 , Figure 2 , Figure 3 , wherein Figure 1 is a schematic diagram of the first embodiment of a 0.4mm outer layer BGA circuit board structure provided by the present utility model; Figure 2 is Figure 1 the compensated schematic diagram shown in; Figure 3 is Figure 1 the three-dimensional structure schematic diagram shown in. A 0.4mm outer layer BGA circuit board structure includes: a circuit board 1;

[0027] A first pad 2, the first pad 2 is arranged on the top of the circuit board 1;

[0028] A second pad 3, the second pad 3 is arranged on the top of the circuit board 1, and through holes 31 are provided inside both the second pad 3 and the circuit board 1.

[0029] Eight first pads 2 are provided, and one second pad 3 is provided.

[0030] The diameter of the first pad 2 is 10 mil, the diameter of the second pad 3 is 16 mil, and the diameter of the through hole 31 is 8 mil.

[0031] The distance from the center of the second pad 3 to the centers of the four surrounding first pads 2 is 15.75 mil.

[0032] The first pads 2 and the second pad 3 are arranged on the top of the circuit board 1 in a 3-row by 3-column form.

[0033] The entire product implementation process, design the pattern according to Figure 2, the top of the pattern is as Figure 1 shown, (the dotted line is the compensated working draft, the solid line is the design original draft, finished product size);

[0034] Main process, using double-sided copper clad laminate cut into specified sizes, realized through drilling, desmearing, electroless copper plating, electroplating, pattern transfer, outer layer etching and subsequent processes;

[0035] Among them, the key dimensions include the first pad 2 with a diameter of 10 mil, the central through-hole of 0.2 mm (8 mil), the second pad 3 with a diameter of 16 mil, the line width of 3 mil, and the compensation value (0.25 mil on one side), achieving a conventional BGA 85-ohm impedance interconnection design with a small pitch of 0.8 mm. Through design optimization, the wiring space for the small pitch is increased; then, by covering the solder mask on the edge of the pad, the bonding force of the pad is improved, realizing the BGA double-line design for high-density interconnection.

[0036] The working principle of a 0.4-mm outer-layer BGA circuit board structure provided by the present utility model is as follows:

[0037] On one side of the circuit board 1, there is a BGA array with 3 rows and 3 columns of pads. Among the 9 pads, except for the central second pad 3, the other first pads 2 have a diameter of 10 mil, and the central second pad 3 has a diameter of 16 mil; the center-to-center distance of the pads is 0.4 mm (15.75 mil); the central second pad 3 is drilled through the top and bottom layers by a 0.2-mm drill bit, and the other 8 pads have no via holes through; the bottom layer is also designed with pads of 16 mil in size;

[0038] For the 8 pads on the surface layer except the central pad, conductive lines extend outward in a radiation form, and the lines meet the PCB processing size specifications, at least 3 mil; there is no line arranged on the top layer for the central pad, and the line is led to the bottom of the circuit board 1 through the through-hole 31 and connected through the bottom-layer pad, so as to realize that all pads have lead wires led out;

[0039] The top and bottom layers are drilled through by mechanical drilling, and then the hole metallization is realized through electroless copper plating and electroplating to conduct the top and bottom layers.

[0040] Compared with the related technology, a 0.4-mm outer-layer BGA circuit board structure provided by the present utility model has the following beneficial effects:

[0041] Through the cooperation of structures such as the first pad 2, the second pad 3, and the through-hole 31, it is possible to lead out a lead wire for each pad in the smallest 3-by-3 nine-grid array without reducing the size of the pad, thereby ensuring the connection strength between each pad and each lead wire.

[0042] Second Embodiment

[0043] Please refer to Figure 4 , based on a 0.4-mm outer-layer BGA circuit board structure provided by the first embodiment of the present application, the second embodiment of the present application proposes another 0.4-mm outer-layer BGA circuit board structure. The second embodiment is only a preferred manner of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0044] Specifically, the difference of a 0.4mm outer layer BGA circuit board structure provided by the second embodiment of the present application lies in that for a 0.4mm outer layer BGA circuit board structure, annular grooves 4 are provided on the tops of both the first pad 2 and the second pad 3.

[0045] The annular grooves 4 are arranged in a circular form in circles on the tops of the first pad 2 and the second pad 3. On the top of the second pad 3, the annular groove 4 is arranged on the outer edge of the through hole 31, so as to avoid affecting the normal use of the through hole 31. And multiple annular grooves 4 can be provided on the top of one pad, so as to increase the connection effect.

[0046] The working principle of a 0.4mm outer layer BGA circuit board structure provided by the present utility model is as follows:

[0047] By providing multiple annular grooves 4 on the tops of the first pad 2 and the second pad 3, when welding the connecting wire, the solder paste can flow into the inner side surface of the annular groove 4, so as to increase the contact area between the solder paste and the first pad and the second pad 3, so as to facilitate increasing the welding strength.

[0048] Compared with the related art, a 0.4mm outer layer BGA circuit board structure provided by the present utility model has the following beneficial effects:

[0049] By arranging the annular grooves 4 on the tops of the first pad 2 and the second pad 3, in this way, when in use, the contact area between the solder paste and the first pad 2 and the second pad 3 can be increased, so as to increase the welding strength.

[0050] Third Embodiment

[0051] Please refer to Figure 5 , based on a 0.4mm outer layer BGA circuit board structure provided by the first embodiment of the present application, the third embodiment of the present application proposes another 0.4mm outer layer BGA circuit board structure. The third embodiment is only a preferred manner of the first embodiment, and the implementation of the third embodiment will not affect the independent implementation of the first embodiment.

[0052] Specifically, the difference of a 0.4mm outer layer BGA circuit board structure provided by the third embodiment of the present application lies in that for a 0.4mm outer layer BGA circuit board structure, circular grooves 5 are provided on the tops of both the first pad 2 and the second pad 3.

[0053] The circular grooves 5 are provided on the tops of the first pad 2 and the second pad 3 and are evenly provided with a plurality of them for better welding connection.

[0054] The working principle of a 0.4mm outer layer BGA circuit board structure provided by the present utility model is as follows:

[0055] When in use, circular grooves 5 are pressed on the tops of the first pad 2 and the second pad 3. During subsequent welding, the solder paste can enter the inner sides of the circular grooves 5, thereby increasing the contact between the solder paste and the first pad 2 and the second pad 3, and thus increasing the connection strength.

[0056] Compared with the related art, a 0.4mm outer layer BGA circuit board structure provided by the present utility model has the following beneficial effects:

[0057] When in use through the setting of the circular grooves 5, the contact area between the solder paste and the first pad 2 and the second pad 3 can be increased, thereby improving the stability and strength after welding.

[0058] The above are only the embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present utility model, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present utility model.

Claims

1. A 0.4mm outer layer BGA circuit board structure, characterized in that: include: Circuit board; A first pad, wherein the first pad is provided with a top portion of the circuit board; A second solder pad, the second solder pad is arranged on the top of the circuit board, a through hole is opened inside the second solder pad and inside the circuit board, an annular groove is arranged on the top of the first solder pad and the second solder pad, and a circular groove is arranged on the top of the first solder pad and the second solder pad.

2. A 0.4 mm outer layer BGA circuit board structure according to claim 1, characterized in that: The number of the first pads is eight, and the number of the second pads is one.

3. A 0.4 mm outer layer BGA circuit board structure according to claim 1, characterized in that: The diameter of the first pad is 10 mil, the diameter of the second pad is 16 mil, and the diameter of the through hole is 8 mil.

4. A 0.4 mm outer layer BGA circuit board structure according to claim 1, characterized in that: The distance between the center of the second pad and the centers of the four surrounding first pads is 15.75 mil.

5. A 0.4 mm outer layer BGA circuit board structure according to claim 1, characterized in that: The first pads and the second pads are arranged on the top of the circuit board in a form of 3 rows by 3 columns.

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