A ball grid array device heat dissipation printed circuit board

Abstract

The present invention discloses a heat dissipation printed circuit board for a ball grid array device, wherein the ball grid array device is arranged on the printed circuit board body, the printed circuit board body corresponding to the ball grid array device is fanned out with the via hole, the via hole is provided with a first heat dissipation pad matching the via hole, and the first heat dissipation pad is connected to the BGA pad on the ball grid array device through a first microstrip line; a second heat dissipation pad connected to the via hole is provided on the back of the printed circuit board body, and the second heat dissipation pad is used to accelerate the speed of heat dissipation of the printed circuit board body; the beneficial effect of the present invention is that by arranging corresponding via holes and heat dissipation pads on the printed circuit board of the ball grid array device, the heat generated by each device in the printed circuit board can be dissipated in time, thereby improving the heat dissipation efficiency of the printed circuit board of the ball grid array device.

Description

Technical Field

[0001] The invention relates to the technical field of circuit board heat dissipation, and in particular to a ball grid array device heat dissipation printed circuit board. Background Art

[0002] At present, the installation density of ball grid array package devices is getting higher and higher. When the printed circuit board is working, the heat generated by the device is also increasing, and the power consumption is increasing. In a high temperature and high humidity environment, long-term operation will cause ion migration inside the printed circuit board material, copper layer fracture in the connection hole, and fatigue of the surface welding point. The above reasons will cause the electrical performance to decline, the noise to increase, and even serious damage.

[0003] Ball grid array package devices use solder columns instead of solder balls. The common heat dissipation method for this type of device is to fix the heat sink on the chip or use a metal heat conductive plate to buckle on the surface of the chip that needs heat dissipation. The heat is transferred to the chassis or printed circuit board through the heat conductive plate. Either method requires a certain bonding force. This force contacts the device and is transferred to the solder ball. If it is not properly controlled, it is easy to affect the reliability of the chip. If the heat conductive plate is lifted to a certain height, a certain gap is maintained with the chip, and silicone rubber is filled in the gap, due to the small gap, the thermal resistance of the silicone rubber is smaller than the thermal resistance between the chip and the printed circuit board, which can effectively dissipate heat. Some scholars have also proposed adding aluminum oxide to silicone rubber to improve thermal conductivity. However, in the current design method of ball grid array package devices, the fixed heat sink and the filled silicone rubber can only dissipate heat in the positive direction of the Z axis on the printed circuit board, and the plastic package shell device also seriously reduces the heat dissipation performance in this direction, reducing the heat transfer rate of the ball grid array package device. In addition, in the current design method, the solder mask on the back of the printed circuit board device also hinders the heat dissipation performance.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The technical problem to be solved by the present invention is that in the prior art, a heat sink is fixed on a ball grid array chip or a metal heat conductive plate is buckled on the surface of the chip that needs heat dissipation for heat dissipation, which cannot dissipate the heat in the Z-axis direction in time, thereby reducing the heat transfer rate of the ball grid array packaged device. The purpose is to provide a ball grid array device heat dissipation printed circuit board that can ensure that the heat at the bottom of the ball grid array device can be quickly conducted to the outside, thereby achieving the purpose of reducing the component temperature and reducing the temperature difference.

[0006] The present invention is achieved through the following technical solutions:

[0007] A ball grid array device heat dissipation printed circuit board comprises a printed circuit board body, a ball grid array device and a via hole, wherein the ball grid array device is arranged on the printed circuit board body, the printed circuit board body corresponding to the ball grid array device fans out the via hole, a first heat dissipation pad matching the via hole is arranged on the via hole, and the first heat dissipation pad is connected to the BGA pad on the ball grid array device through a first microstrip line; a second heat dissipation pad connected to the via hole is arranged on the back of the printed circuit board body, and the second heat dissipation pad is used to accelerate the speed at which the printed circuit board body dissipates heat.

[0008] Conventionally, when heat is dissipated from a ball grid array device, a heat sink is usually fixed on the ball grid array chip or a metal heat conductive plate is pressed on the surface of the chip that needs heat dissipation. However, when this method is used to dissipate heat from the ball grid array device, the heat in the Z-axis direction cannot be dissipated in time, thereby reducing the heat transfer rate of the ball grid array packaged device. The present invention provides a heat dissipation printed circuit board for a ball grid array device. By arranging corresponding vias and heat dissipation pads on the printed circuit board of the ball grid array device, the heat generated by each device in the printed circuit board can be dissipated in time, thereby improving the heat dissipation efficiency of the printed circuit board of the ball grid array device.

[0009] Preferably, the second heat dissipation pad includes a second microstrip line, a sub-heat dissipation pad and a circular pad, the sub-heat dissipation pad matches the via hole, and the sub-heat dissipation pad is arranged on the via hole, and the sub-heat dissipation pad and the circular pad are connected by the second microstrip line and are both arranged on the back of the printed circuit board.

[0010] Preferably, the diameter of the circular pad is greater than or equal to the diameter of the BGA pad.

[0011] Preferably, the via hole is an elliptical column hole, and the major axis direction of the elliptical column hole is consistent with the fan-out direction of the printed circuit board body.

[0012] Preferably, the length of the major axis of the elliptical cylindrical hole ranges from twice to five times the length of the minor axis.

[0013] Preferably, the length of the short axis ranges from 0.2 mm to 1 mm.

[0014] Preferably, the width of the first microstrip line and the width of the second microstrip line are both greater than or equal to the diameter of the BGA pad.

[0015] Preferably, the printed circuit board is a double-sided printed circuit board or a multi-layer printed circuit board.

[0016] Preferably, the diameter of the BGA pad ranges from 0.4 mm to 3 mm.

[0017] Preferably, in the heat dissipation printed circuit board, when the via hole is an elliptical cylindrical hole, the specific calculation expression of the elliptical cylindrical hole is:

[0018]

[0019] I is the circuit current, k is the compensation coefficient, ΔT is the allowable temperature rise, D1 is the diameter of the long side of the elliptical via, D2 is the diameter of the short side of the elliptical via, t p is the via copper plating thickness.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] A ball grid array device heat dissipation printed circuit board provided in an embodiment of the present invention can dissipate the heat generated by each device in the printed circuit board in a timely manner by arranging corresponding vias and heat dissipation pads on the printed circuit board of the ball grid array device, thereby improving the heat dissipation efficiency of the ball grid array device printed circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A top view of a heat dissipation printed circuit board for a ball grid array device;

[0024] Figure 2 A cross-sectional view of a heat dissipation printed circuit board for a ball grid array device;

[0025] Figure 3 A top view of the heat dissipation pad structure of a ball grid array device heat dissipation printed circuit board;

[0026] Figure 4 Bottom view of the heat sink pad structure of the ball grid array device.

[0027] Reference numerals:

[0028] 1. Printed circuit board body; 2. Via hole; 3. Ball grid array device; 4. BGA pad; 5. First heat dissipation pad; 6. First microstrip line; 7. Second microstrip line; 8. Round pad; 9. Sub-heat dissipation pad. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0031] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0033] Conventionally, when cooling the ball grid array device 3, a heat sink is usually fixed on the ball grid array chip or a metal heat conductive plate is pressed on the surface of the chip that needs heat dissipation. However, when this method is used to cool the ball grid array device 3, the circular via 2 design after the fan-out of the ball grid array package device pad is too small for the circular via 2 copper column, resulting in a too small heat dissipation channel area in the negative direction (vertical direction) of the Z axis, which is not conducive to the heat dissipation performance of the heat dissipation channel in the negative direction of the Z axis; the back of the printed circuit board device only includes the via 2 pad, and a resin solder resist is added. The back heat dissipation pad is too small, which is not conducive to forming a heat dissipation path for thermal radiation, greatly reducing the heat dissipation performance of the heat dissipation channel in the negative direction of the Z axis.

[0034] The present embodiment discloses a ball grid array device heat dissipation printed circuit board. By providing corresponding vias 2 and heat dissipation pads on the printed circuit board of the ball grid array device 3, the heat generated by each device in the printed circuit board can be dissipated in time, thereby improving the heat dissipation efficiency of the printed circuit board of the ball grid array device 3.

[0035] The specific configuration structure of this embodiment is shown in the figure Figure 1 As shown, it includes a printed circuit board body 1, a ball grid array device 3 and a via 2, the ball grid array device 3 is on the printed circuit board body 1, the printed circuit board body 1 corresponding to the ball grid array device 3 is fanned out to set the via 2, the via 2 is provided with a first heat dissipation pad 5 matching therewith, and the first heat dissipation pad 5 is connected to the BGA pad 4 on the ball grid array device 3 through a first microstrip line 6; the back of the printed circuit board body 1 is provided with a second heat dissipation pad connected to the via 2, and the second heat dissipation pad is used to accelerate the speed of heat dissipation of the printed circuit board body 1; the first microstrip line 6 is used to connect between the pad of the ball grid array device 3 and the elliptical via 2, the width of the first microstrip line 6 W1 ≥ the pad diameter P1, and the minimum width is calculated by the circuit current carrying formula;

[0036] In the present embodiment, the ball grid array device 3 is a heat dissipation device, and the printed circuit board can be a double-sided board or a multi-layer board. There is no corresponding restriction on the number of layers and type of the specific board. The only difference is that the ball grid array device 3 is arranged on the printed circuit board, and then the vias 2 and the corresponding heat dissipation plate are arranged in the fan-out direction of the ball grid array device 3 corresponding to the printed circuit board. The vias 2 can accelerate the heat dissipation speed on the printed circuit board, thereby improving the heat dissipation efficiency of the ball grid array device 3.

[0037] The via 2 is an elliptical column hole, and the direction of the major axis of the elliptical column hole is consistent with the fan-out direction of the printed circuit board body 1. The length of the major axis of the elliptical column hole ranges from twice to five times the length of the minor axis. The length of the minor axis ranges from 0.2 mm to 1 mm.

[0038] In this embodiment, the via hole 2 is an elliptical via hole 2, which is between the four pads of the ball grid array device, the diameter of the device pad is P1, the long side direction of the elliptical via hole 2 is consistent with the fan-out direction, the short side / long side of the diameter of the elliptical via hole 2 is D1 / D2, and the diameter of the long side D2 is between 2D1 and 5D1, D1 is generally between 0.2 mm and 1 mm, and the minimum size of D1 / D2 is calculated by the calculation method of the elliptical via hole 2. The first microstrip line 6 is used to connect the BGA pad 4 of the ball grid array device 3 and the elliptical via hole 2, and the microstrip line width W1 is calculated to be ≥ the diameter P1 of the BGA pad 4;

[0039] The second heat dissipation pad includes a second microstrip line 7, a sub-heat dissipation pad and a circular pad 8. The sub-heat dissipation pad matches the via 2 and is arranged on the via 2. The sub-heat dissipation pad and the circular pad 8 are connected by the second microstrip line 7 and are both arranged on the back of the printed circuit board.

[0040] The back of the printed circuit board of the ball grid array device 3 is designed with a second heat dissipation pad connected to the elliptical via 2. The second heat dissipation pad is composed of the second microstrip line 7 width W2 and the circular pad 8P2. The elliptical via 2 and the circular pad 8P2 are connected by the second microstrip line 7 width W2. The circular pad 8P2 ≥ the diameter P1 of the BGA pad 4, and the microstrip line width W2 ≥ the diameter P1 of the BGA pad 4.

[0041] The width of the first microstrip line 6 and the width of the second microstrip line 7 are both greater than or equal to the diameter of the BGA pad 4; the printed board is a double-sided printed board or a multi-layer printed board. The diameter of the BGA pad 4 ranges from 0.4 mm to 3 mm.

[0042] Through this design method, heat is conducted along the larger area of ​​the heat-conducting elliptical via 2, which can expand the heat dissipation path area of ​​the ball grid array device 3 printed circuit board. A heat dissipation pad connected to the elliptical via 2 is designed on the back, which expands the size of the back heat dissipation pad, which is conducive to forming a heat dissipation path for larger area heat radiation, and greatly improves the heat dissipation performance of the heat dissipation channel in the negative direction (vertical direction) of the Z axis. This method forms a low thermal resistance heat dissipation channel, ensuring that the heat at the bottom of the ball grid array device 3 can be quickly conducted to the outside, achieving the purpose of reducing the component temperature and reducing the temperature difference. It not only reduces the device failure caused by the excessive temperature of the ball grid array device 3, but also greatly improves the reliability of electronic products. A solder mask area is designed on the back of the printed circuit board where the ball grid array device 3 is installed, and the solder mask area is ≥ the second heat dissipation pad on the back.

[0043] The current-carrying width of the microstrip line and the minimum loop width control requirements of the elliptical via 2 described in this embodiment are calculated and controlled. Specifically, they are based on the following expression:

[0044] Circuit current calculation method:

[0045] I=kΔT 0.44 A 0.725

[0046] Where: I is the circuit current, k is the compensation coefficient, ΔT is the allowable temperature rise, and A is the conductor cross-sectional area.

[0047] Calculation method for circular vias:

[0048] I=kΔT 0.44 [π(d+t p )t p ]0.725

[0049] Where: I is the circuit current, k is the compensation coefficient, ΔT is the allowable temperature rise, d is the diameter of the finished via, that is, the diameter after copper plating; t p is the via copper plating thickness;

[0050] In the heat dissipation printed circuit board, when the via hole 2 is an elliptical cylindrical hole, the specific calculation expression of the elliptical cylindrical hole is:

[0051]

[0052] I is the circuit current, k is the compensation coefficient, ΔT is the allowable temperature rise, D1 is the diameter of the long side of the elliptical via, D2 is the diameter of the short side of the elliptical via, t p is the via copper plating thickness.

[0053] The present embodiment discloses a heat dissipation printed circuit board of a ball grid array device 3. The method forms a low thermal resistance heat dissipation channel, which ensures that the heat at the bottom of the ball grid array device 3 can be quickly transferred to the outside, so as to reduce the temperature of the components and the temperature difference. It not only reduces the failure of the device caused by the excessive temperature of the ball grid array device 3, but also greatly improves the reliability of electronic products; by designing to expand the heat dissipation path area of ​​the ball grid array device 3 printed circuit board, a heat dissipation pad connected to the elliptical via 2 is designed on the back, and the size of the heat dissipation pad on the back is expanded, which is conducive to forming a heat dissipation path with a larger area of ​​heat radiation, and greatly improves the heat dissipation performance of the heat dissipation channel in the negative direction (vertical direction) of the Z axis.

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A ball grid array device heat dissipation printed circuit board, characterized in that: The invention comprises a printed circuit board body (1), a ball grid array device (3) and a via hole (2), wherein the ball grid array device (3) is arranged on the printed circuit board body (1), the printed circuit board body (1) corresponding to the ball grid array device (3) fans out the via hole (2), the via hole (2) is an elliptical column hole, and the major axis direction of the elliptical column hole is consistent with the fan-out direction of the printed circuit board body (1), the via hole (2) is provided with a first heat dissipation pad (5) matching the via hole (2), and the first heat dissipation pad (5) is connected to the BGA pad (4) on the ball grid array device (3) through a first microstrip line (6); the back of the printed circuit board body (1) is provided with a second heat dissipation pad connected to the via hole (2), and the second heat dissipation pad is used to accelerate the speed at which the printed circuit board body (1) dissipates heat.

2. A ball grid array device heat dissipation printed circuit board according to claim 1, characterized in that: The second heat dissipation pad comprises a second microstrip line (7), a sub-heat dissipation pad and a circular pad (8); the sub-heat dissipation pad matches the via hole (2) and is arranged on the via hole (2); the sub-heat dissipation pad and the circular pad (8) are connected via the second microstrip line (7) and are both arranged on the back of the printed circuit board.

3. A ball grid array device heat dissipation printed circuit board according to claim 2, characterized in that: The diameter of the circular pad (8) is greater than or equal to the diameter of the BGA pad (4).

4. A ball grid array device heat dissipation printed circuit board according to claim 1, characterized in that: The length of the major axis of the elliptical cylindrical hole ranges from twice to five times the length of the minor axis.

5. A ball grid array device heat dissipation printed circuit board according to claim 4, characterized in that: The length of the short axis ranges from 0.2 mm to 1 mm.

6. A ball grid array device heat dissipation printed circuit board according to claim 2, characterized in that: The width of the first microstrip line (6) and the width of the second microstrip line (7) are both greater than or equal to the diameter of the BGA pad (4).

7. A ball grid array device heat dissipation printed circuit board according to claim 1, characterized in that: The printed board is a double-sided printed board or a multi-layer printed board.

8. A ball grid array device heat dissipation printed circuit board according to claim 1, characterized in that: The diameter of the BGA pad (4) ranges from 0.4 mm to 3 mm.

9. A ball grid array device heat dissipation printed circuit board according to claim 1, characterized in that: In the heat dissipation printed circuit board, when the via hole (2) is an elliptical cylindrical hole, the specific calculation expression of the elliptical cylindrical hole is: I is the circuit current, k is the compensation coefficient, ΔT is the allowable temperature rise, D1 is the diameter of the long side of the elliptical via, D2 is the diameter of the short side of the elliptical via, t p is the via copper plating thickness.

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