TWI446148B - Printed circuit board assembly - Google Patents

Description

Board combination

The invention relates to a circuit board assembly, in particular to a circuit board combination provided with a heat sink.

With the continuous development of computer technology, more and more computer functions, and more and more computer components, in order to improve the stability of computer work, the computer uses a lot of heat sinks, the current use of the radiator in the computer is mainly used For heat dissipation from the chip, it is important to fix the heat sink on the board.

The industry also introduces a wafer heat sink fixing clip, which is a clamp unit for conveniently fixing an aluminum extruded heat sink to the surface of the wafer, and an intermediate frame and elastic fasteners disposed at two diagonal ends of the frame. The elastic fastener is formed into a continuous curved section, and a hook shape is formed at the end for inserting into a fastening hole of a corresponding position on the printed circuit board, and the elastic fastener is integrally formed with the intermediate frame. When assembled, the frame can be embedded in the press-fit groove on the surface of the aluminum extruded heat sink. However, due to environmental considerations, the lead-free solder is usually used to solder the wafer base, and the soldering feet of the wafer base are relatively brittle. During the assembly of the heat sink, one end of the fixing clip is buckled into the fastening hole of the circuit board, and the circuit board has a certain deformation, so that It is possible that the soldering feet of the wafer base on the circuit board are loose, and the fixing clip has a certain elastic force applied to the heat sink, and the heat sink itself has a certain weight, so that the wafer mounted on the wafer base is subjected to external pressure and is easy to be pressed. Causes damage to the solder fillet of the wafer base.

In view of the above, it is necessary to provide a circuit board combination that effectively prevents the heat sink from damaging the wafer base solder fillet.

A circuit board assembly includes a circuit board, a wafer base mounted on the circuit board, and a heat sink mounted on the base of the wafer, the heat sink having a base and a plurality of heat dissipation fins extending upward from the base. The four corners of the base of the wafer are respectively provided with downwardly extending legs, and the legs of the wafer base are supported on the circuit board.

Compared with the prior art, the legs on the wafer base support the wafer base to prevent excessive pressure from being applied to the solder layer between the circuit board and the wafer base, and the circuit board combination can effectively prevent pressure damage of the solder fillet.

10, 10'‧‧‧ radiator

11, 11'‧‧‧ radiator base

12, 12'‧‧‧ Heat sink fins

20, 20’‧‧‧ boards

21‧‧‧Opening

21’‧‧‧Clock Department

30, 30'‧‧‧ wafer base

31, 31'‧‧‧ wafer base feet

40, 40’‧‧‧ wafer

50‧‧‧ solder layer

50’‧‧‧Steel wire

51’‧‧‧ hook

60'‧‧‧ solder layer

110, 110’‧‧‧ radiator base feet

111‧‧‧Limited

112‧‧‧Insert Department

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective exploded view of a preferred embodiment of a circuit board assembly of the present invention.

2 is a cross-sectional view showing the assembled circuit board of FIG. 1.

3 is an exploded perspective view of another preferred embodiment of the circuit board assembly of the present invention.

4 is a cross-sectional view showing the assembled circuit board of FIG. 3.

Referring to FIGS. 1 and 2, a circuit board assembly includes a circuit board 20, a wafer base 30 mounted on the circuit board 20, a wafer 40 mounted on the wafer base 30, and a wafer 40 mounted thereon. Radiator 10.

The heat sink 10 is provided with a base 11 and a plurality of heat dissipation fins 12 extending upward from the base 11 . The base 11 is provided with a downwardly extending leg 110 at each of the four corners. The leg 110 is generally in the shape of a step. Each leg 110 is provided with a limiting portion 111 having a larger cross-sectional area and a limiting portion. 111 is formed by extending the insertion portion 112 having a small cross-sectional area . The wafer base 30 is mounted on the circuit board 20, and the lower surface thereof is provided with a downwardly extending leg 31 at each of the four corners. A solder layer 50 is applied between the wafer base 30 and the circuit board 20. The circuit board 20 is provided with an opening 21 corresponding to the insertion portion 112. The cross-sectional area of the opening 21 is smaller than the cross-sectional area of the limiting portion 111 to restrict the limiting portion 111 from passing through the opening. 21, the vertical height of the limiting portion 111 is slightly larger than the vertical height of the wafer base 30. The wafer 40 is mounted on the wafer base 30 and slightly higher than the upper surface of the wafer base 30, and the upper surface of the wafer 40 is coated. There is a layer of thermally conductive medium that is in contact with the lower surface of the base 11.

When the heat sink 10 is mounted, the insertion portion 112 of the heat sink 10 passes through the opening 21 of the circuit board 20. The limiting portion 111 cannot pass through the opening 21 and is opposite to the upper surface of the circuit board 20. The base 11 of the heat sink 10 is pressed against the wafer 40 on the wafer base 30. Since the limiting portion 111 of the leg 110 is supported on the circuit board 20, the legs 110 carry most of the gravity of the heat sink 10. Thus, the wafer base 30 and the wafer 40 bear the pressure exerted by the heat sink 10 to be reduced. The insertion portion 112 of the heat sink 10 is fixed to the circuit board 20 by soldering, bonding, or screwing. In addition, since the legs 31 support the wafer base 30 on the circuit board 20, the legs 31 carry most of the gravity of the wafer base 30 and the wafer 40, thereby further reducing the pressure on the wafer base 30 and avoiding The solder layer 50 between the circuit board 20 and the wafer base 30 is subjected to excessive pressure to cause damage to the solder fillet.

Referring to FIG. 3 and FIG. 4, in another embodiment of the circuit board assembly of the present invention, a circuit board assembly includes a circuit board 20', a wafer base 30' mounted on the circuit board 20', and an assembly The wafer 40' on the wafer base 30', a heat sink 10' mounted on the wafer 40', and a conventional heat sink clip, in the present embodiment, the buckle is an elastic steel wire 50'.

The heat sink 10' is provided with a base 11' and a plurality of heat radiating fins 12' extending upward from the base 11'. The base 11' is respectively provided with a downwardly extending leg 110' at each of the four corners. The vertical height of each leg 110' is slightly higher than the vertical height of the wafer base 30'. The wafer 40' is mounted on the wafer base 30. 'Upper and slightly above the upper surface of the wafer base 30', the upper surface of the wafer 40' is coated with a layer of thermally conductive medium and is in contact with the lower surface of the base 11'. The wafer base 30' is mounted on the circuit board 20', and its lower surface is provided with a downwardly extending leg 31' at each of the four corners. A solder layer 60' is applied between the wafer substrate 30' and the circuit board 20'. Each of the ends of the wire 50' is provided with a hook 51', and the circuit board 20' is provided with an engaging portion 21' for engaging the hook 51'.

When the heat sink 10' is mounted, the heat sink 10' is first placed on the wafer base 30'. At this time, the base 11' of the heat sink 10' presses the wafer 40' on the wafer base 30'. The foot 110' is supported on the circuit board 20', and the legs 110' carry most of the weight of the heat sink 10' so that the pressure exerted by the wafer base 30' and the wafer 40' on the heat sink 10' is reduced. The wire 40' is then passed through the heat sink 10' and the hooks 41' at the two ends thereof are respectively engaged with the engaging portions 21' of the circuit board 20', thereby fixing the heat sink 10' to the circuit board 20. 'on. In addition, since the legs 31' support the wafer base 30' on the circuit board 20', the legs 31' carry most of the weight of the wafer base 30' and the wafer 40', thereby further reducing the wafer base 30. The pressure on the upper side avoids the damage of the solder fillet caused by the excessive pressure of the solder layer 60' between the circuit board 20' and the wafer base 30'.

In the above two embodiments, the legs 31, 31', 110, 110' may be provided in plurality, which may be different shapes; the circuit boards 20, 20' may be in the legs 31, 31', 110' corresponding to the position is provided with a groove to allow the legs 31, 31', 110' better positioning; the legs 110, 110' may be non-integrally formed with the heat sinks 10, 10', and are fixed as a single component to the base of the heat sink 10, 10', which constitutes a downward extension of the base. Feet.

In summary, this creation has indeed met the requirements of the invention patent, and has filed a patent application in accordance with the law. However, the above description is only a preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art of the present invention should be included in the following claims.

10‧‧‧ radiator

11‧‧‧ radiator base

12‧‧‧ Heat sink fins

20‧‧‧ boards

21‧‧‧Opening

30‧‧‧ wafer base

31‧‧‧ wafer base feet

40‧‧‧ wafer

110‧‧‧ radiator base feet

111‧‧‧Limited

112‧‧‧Insert Department

Claims (5)

A circuit board assembly comprising a circuit board, a wafer base mounted on an upper surface of the circuit board, and a heat sink mounted on the wafer base, the heat sink having a base and a plurality of upwardly extending from the base a heat dissipating fin, wherein the four corners of the base of the wafer are respectively provided with a downwardly extending first leg, the first leg is supported on the circuit board, and the base of the heat sink is provided with a plurality of downwardly extending a second leg, each of the second legs is provided with a limiting portion and an insertion portion having a cross section smaller than the limiting portion, the circuit board is provided with a plurality of openings, the insertion portion is passed through the upper surface of the circuit board The opening is located on a lower surface of the circuit board, and the limiting portion is in contact with the upper surface of the circuit board to carry the heat sink. The circuit board assembly of claim 1, wherein a wafer is disposed between the heat sink and the wafer base, and the wafer is mounted on the wafer base. The circuit board assembly of claim 1, wherein the heat sink is fixed to the circuit board via a heat sink clip. The circuit board assembly of claim 1, wherein a solder layer is disposed between the wafer base and the circuit board. The circuit board assembly of claim 1, wherein the upper surface of the wafer is coated with a layer of heat conductive medium and is in contact with a lower surface of the heat sink base.