TW202445025A - Reworkable fixing element - Google Patents

Abstract

A reworkable fixing element includes a screw having a spring fitted thereon, a screw head with two opposite cuts, and a retaining ring for stopping the screw from axially moving down any further; a sleeve disposed outside the screw and the spring, and including two opposite windows near an upper end thereof and a coupling zone located below the windows; a spring retaining ring fitted around the coupling zone and including two upward hooked arms extended through the windows to press the spring to a compressed state. The used fixing element has an elastically released spring but is reworkable using a reworking tool, which pushes the spring into the sleeve via the two cuts. Then, the hooked arms are allowed to extend through the windows to press on and hold the spring in the compressed state again, and the fixing element is ready for use a second time.

Description

Fixing elements with heavy-duty functions

The present invention relates to a fixing component with a rework function, and more particularly to a fixing component with a rework function that can provide uniform downward pressure to prevent damage or thermal resistance caused by uneven contact force between a bare chip computing unit and a heat sink, and can be reassembled by being used in conjunction with a rework fixture.

In order to provide electronic devices with high-performance computing capabilities, high-performance and high-power chips are currently used. When the chip is operating, it generates a lot of heat. Traditional computing chips have a packaging shell outside, and the packaging shell covers the chip inside to protect the chip from damage. As the computing performance of the chip increases, the chip will generate a higher temperature than the traditional one when performing computing work. The external packaging shell of the chip has seriously affected the heat dissipation of the chip and the efficiency of heat conduction to the outside; therefore, most chips on the market have been changed to the bare chip form for installation. Since the bare chip surface is not equipped with a protective packaging shell, its heat exchange contact surface is small, and the surface is not a flat surface. Also, without the protection of the external packaging shell, its strength is relatively low, so it is easy to crack when combined with a heat sink. Therefore, when the heat sink is fixed on the heat source (bare crystal), since the heat source itself cannot be directly combined with the heat sink, a copper column with internal threads is set up on the substrate (motherboard or circuit board) where the heat source is set as a supporting locking point, and the locking point is located in the direction of the four corners of the outer side of the heat source. If the traditional single locking point is used to lock in sequence, the position of the first locking will be tilted, and the bare crystal cannot withstand such uneven pressure, which will cause problems such as chip cracking and damage. Referring to Figures 1 and 2, which are schematic diagrams of a heat sink and a bare die assembly, the heat source A is set on a substrate D, and copper pillars B with internal threads are set at four corners of the substrate D corresponding to the outer side of the heat source A. The heat sink C is also provided with four holes C3 at positions corresponding to the copper pillars B and is penetrated by screw units C1. The screw units C1 are provided with a spring C2 on the outer sleeve. When the heat sink C is locked and combined with the heat source A, it is usually done by a single point screwing operation operated by a manual or robot arm with an electric screwdriver. In order to speed up the assembly time on the production line and in a limited time, The assembly is completed within the assembly time. Usually, each screw is fastened directly and quickly at one time. When the screw unit C1 is fastened to the fixed point one by one, the spring C2 sleeved on the screw unit C1 also supports the heat source A at the same time. The lack of uneven force caused by the single-point locking immediately causes the heat source to collide. As mentioned above, the heat source A (bare crystal) is brittle. However, the single-point screw unit C1 locking and the spring C2 pressure cannot provide complete and comprehensive (four corners of the bare crystal) synchronous and uniform downward pressure for the heat source A (bare crystal). The bare crystal is easily damaged due to uneven force. Furthermore, the bare die is quite fragile. As mentioned above, the four corners of the bare die must provide a uniform downward pressure to provide a bonding force for assembly. If the four corners of the bare die cannot be uniformly pressed downward, it is easy to cause the heat sink or heat dissipation device to warp and not completely fit or be damaged between the heat source (bare die), and it is easy to form thermal impedance, which will cause uneven heating or thermal conduction failure. In addition, some industry insiders have provided a heat sink device that uses a spring screw in combination with a bare die heat source to solve the problem that the prior art cannot provide uniform downward pressure at the same time. This type of spring screw is different from a general spring screw. The screw body of the spring screw and the outside of the spring are additionally provided with a screw sleeve, and a spring limiting element is additionally provided outside the screw sleeve. The spring can be temporarily compressed in the screw sleeve through the spring limiting element. After the spring limiting element is destroyed by a machine or a hand tool, the spring that was originally compressed and restricted in the screw sleeve can be released simultaneously. The spring tension provided by the two ends of the spring upward and downward assists the heat sink to provide uniform pressure to the heat source. Although the spring screw can provide spring force through the spring to adjust or assist the downward pressure, the spring limiter in the spring screw that limits the spring force can only be used once. When the spring limiter is damaged and the compressed spring is released, the spring cannot be reset after being released. If it is to be reinstalled and used, the spring screw must be removed from the heat sink first, and then replaced with a new spring screw so that it can be reinstalled and locked again. Therefore, how to improve the heat dissipation device to fully and comprehensively provide uniform pressure to fit tightly with the heat source, and how to maintain the appropriate bonding force between the bare die and the heat dissipation device and enable repeated installation or adjustment are the primary issues that the industry needs to solve.

Therefore, in order to effectively solve the above-mentioned problems, the main purpose of the present invention is to provide a fixing component with a rework function, which can not only provide synchronous and uniform downward pressure, but also effectively avoid the effect of cracking or breaking the corners of the bare chip computing unit caused by the single locking point being locked first. Furthermore, the fixing component of the present case can be used in conjunction with a rework fixture, and its spring can be compressed and reset before being reassembled and used again. The fixing element with heavy-duty function comprises: a screw, a sleeve, and a spring ring; The screw has a screw, and the upper and lower ends of the screw respectively have a screw head and a plurality of external threads, and the screw head is provided with two through-going opposite cuts, and the lower end of the screw is adjacent to the upper part of the external thread and provided with a retaining ring receiving groove for retaining a retaining ring, and a spring is sleeved on the outside of the screw, and one end of the spring abuts against the retaining ring. The sleeve has an open upper end and a lower end. An accommodation space is formed inside the sleeve between the upper and lower ends. A pair of windows are recessed inward near the upper end of the sleeve. The windows correspond to each other and are radially connected to the accommodation space. A coupling area is provided on the outer side of the sleeve. The sleeve is simultaneously sleeved on the outside of the screw and the spring. The spring ring is sleeved on the joint area of the sleeve. A hook arm group extends upward from one side of the spring ring. The hook arms extend from the two windows of the sleeve into the accommodation space inside the sleeve to press and clamp one end of the spring, so that the spring is compressed in the sleeve. When combined with a heat source in the form of a bare crystal, the spring ring is pressed by an external object, forcing the hook arms to be disengaged from the buckling of the top end of the spring after being linked, so that the spring can release its spring force to provide downward compression. In addition, when the spring of the fixing element is released after assembly, if the fixing element needs to be reassembled, the spring must be compressed and reset before it can be assembled and used again. The rework can be performed through a rework jig with at least two pressing columns. The pressing columns of the rework jig are inserted into the two cutouts corresponding to the screw head, and the spring is directly pressed downward in the sleeve accommodating space to be compressed. Then, the two hook arms of the spring ring are inserted into the sleeve window to buckle the spring, so that the fixing element can be reinstalled again.

The above-mentioned purpose of the present invention and its structural and functional characteristics will be explained according to the preferred embodiments of the attached drawings. Please refer to Figures 3 and 4, which are the decomposition and assembly diagrams of the fixing element with reworking function of the present invention. As shown in the figure, the fixing element with reworking function can be reworked and reset by matching a reworking fixture P, and then assembled and used again. The fixing unit 1 includes: a screw 11, a sleeve 12, and a spring ring 13; The upper and lower ends of the screw 11 respectively have a screw head 112 and a plurality of external threads 113. The screw head 112 has two cutouts 114. The cutouts 114 penetrate the screw head 112 along the axial direction of the screw 111 and are arranged parallel to each other. The screw head 112 has an upper end surface 1121 and a lower end surface 1122. The cutouts 114 penetrate the upper and lower end surfaces 1121 and 1122 of the screw head 112 at the same time. A retaining ring receiving groove 115 is provided above the screw 111 near the outer thread 113, and a retaining ring 116 is clamped in the retaining ring receiving groove 115; a spring 117 is sleeved on the outside of the screw 111, and the spring 117 is arranged between the screw head 112 and the retaining ring 116. The spring 117 has a top end 1171 and a bottom end 1172. The bottom end 1172 of the spring 117 abuts against the retaining ring 116, and the retaining ring 116 provides axial limitation for the bottom end 1172 of the spring 117 to prevent the spring 117 from escaping from the screw 11. The sleeve 12 has an open upper end 121, a lower end 122, and a receiving space 123. The receiving space 123 is formed in the sleeve 12 between the upper and lower ends 121 and 122. The sleeve 12 is provided with a pair of windows 125 recessed inward near the upper end 121. The windows 125 are spaced correspondingly from each other or arranged at 180 degrees or equal angles, and the windows 125 are radially connected to the receiving space 123. The sleeve 12 is sleeved on the outer portion of the screw 111 through which the spring 117 is provided. The window 125 has an upper edge 1251, and a bonding area 124 is formed between the lower edge of the window 125 and the lower end 122 of the sleeve 12. The bonding area 124 can be selected to have the same diameter as the sleeve or formed by the sleeve 12 being narrowed inward. The outer diameter of the bonding area 124 is smaller than the outer diameter of the remaining parts of the sleeve 12, so the outer part of the sleeve 12 has to form a different step outer diameter, that is, the lowermost side of the bonding area 124 connected to the sleeve 12 has a step portion 1252, and the step portion 1252 can provide axial limitation for the snap ring 13 to prevent the snap ring 13 from excessively moving downward and escaping from the bonding area 124. The spring ring 13 is sleeved on the coupling area 124 of the sleeve 12. The spring ring 13 has a hook arm set 132 extending upward from the upper side. The hook arm set 132 has a pair of hook arms 132A. The ends of the free ends of the hook arms 132A are bent inward to have a hook end 1321. The hook ends 1321 extend into the accommodating space 123 of the sleeve 12 from the aforementioned windows 125. The top end 1171 of the spring 117 is stretched upward to support the top end 1171 of the spring 117. The hook end 1321 moves upward, and the upward movement is limited because the upper surface of the hook end 1321 extending horizontally is pressed against the upper edge 1251 of the window 125, and the top end 1171 of the spring 117 is pressed, inhibiting the spring from continuing to stretch upward, and further making the spring 117 compressed in the sleeve. The spring ring 13 and the sleeve 12 can be loosely or tightly fitted in the joint area 124. During assembly of this embodiment, after the screw 11 with the spring 117 is placed into the receiving space 123 of the sleeve 12, the spring 117 is axially restricted by the hook ends 1321 of the hook arms 132A of the spring ring 13, so that it cannot be pushed up or stretched, and thus the spring 117 is in a compressed state. Please refer to Figures 5, 6, and 7, which are schematic diagrams of the fixed element with a reworking function of the present invention. As shown in the figure, the present invention provides a fixed element with a reworking function. In the embodiment of this description, the fixed element 1 is applied to a heat sink 2 and a heat source 3 in a bare crystal state for assembly as an illustration. The heat sink 2 has a first side 21, a second side 22, and a heating area 23. The heating area 23 is located near the center of the second side 22 of the heat sink 2. The fixing elements 1 are arranged at the four corners of the outer side of a heating area 23 of the heat sink 2. When the heat sink 2 is to provide the heat source 3 with heat exchange or heat conduction, the screws 11 of the fixing elements are firstly screwed and fixed to a fixing structure 4 (a stud with an inner thread) arranged at the four corners adjacent to the heat source 3 through the outer threads 113. At this time, the spring 117 sleeved on the outside of the screw 11 has not released its elastic force, and the heat sink body 2 is only placed and positioned above the heat source 3 without any pressure on the heat source 3, that is, the surface (the second side 22) of the heating area 23 of the heat sink 2 only lightly touches the surface of the heat source 3. In order to provide uniform downward pressure, the fixing elements 1 disposed at the four corners of the outer side of the heating area 23 of the heat sink 2 must release their springs 117 simultaneously and synchronously, so as to provide uniform downward pressure to the heat sink 2 and the heat source 3. In order to simultaneously and synchronously trigger the springs 117 of each fixing element 1 to release their elastic force, a device (not shown) is required in combination with a pressing fixture 5, so as to make each fixing element 1 synchronously actuate to provide downward pressure. The device (not shown) can be a punch or other mechanical device or tool that can provide downward pressure. The device (not shown) is connected to the downward pressing fixture 5. The downward pressing fixture 5 has at least one pressing extension 51. The pressing extension 51 is arranged corresponding to the fixing element 1 arranged at the four corners of the heating area 23 of the heat sink body 2, and abuts against a pressing portion on the upper side of the retaining spring ring 13. When the device (not shown) drives the pressing fixture 5 to move downward, the pressing extension 51 simultaneously presses the contact portion 131 of the retaining ring 13 downward, and the contact portion of the retaining ring 13 and the sleeve 12 form a rotation fulcrum A. When the pressing fixture 5 presses the retaining ring 13 downward, the contact portion 131 of the retaining ring 13 is pressed downward. When the contact portion 131 is subjected to the following pressure, the spring ring 13 is supported by the fulcrum A, and the contact portion 131 is turned outward and downward, and at the same time, the hook arms 132A are driven to withdraw from the window 125 in the radially outer direction of the sleeve 12, and are stretched and expanded outward, and the hook ends 1321 of the hook arms 132A are released from the pressing buckle on the top end 1171 of the spring 117, so that The spring 117 completely releases its limited spring tension, and the top end 1171 of the spring 117 presses against the lower end surface 1221 of the screw head 112, and the bottom end 1172 of the spring 117 on the fixing element 1 at the four corners simultaneously provides uniform downward pressure to the four corners of the heat sink 2, thereby making the heat sink 2 evenly fit downward to the heat source 3. The screw 11 of the present invention only installs and positions the heat sink body 2 above the heat source 3. The actual pressure provided by the heat sink 2 to the heat source 3 is provided by the springs 117 outside the screws 11 at the four corners. Therefore, after the springs are released, a synchronous and uniform downward pressure is provided to solve the defects of the conventional single locking point locking one by one, resulting in uneven force or one-time locking force or excessive spring pressure, resulting in uneven force on the chip, resulting in warping or direct cracking and damage. In addition to providing uniform downward pressure on the heat sink 2 and the heat source 3, the fixing element 1 of the present invention can also provide a rework (reinstallation) function when the heat sink 2 needs to be reinstalled, replaced, adjusted, or reworked after installation. Therefore, when rework (reinstallation) is required, it is used in conjunction with a preset rework jig P to compress the spring 117 in the sleeve to reset it for reinstallation. The heavy work fixture P has a head P1, and at least two independently arranged pressure columns P2 protrude from one end of the head P1. The pressure columns P2 can correspond to the two cutouts 114 through which the screw head 112 is penetrated. When downward pressure is applied to the heavy work fixture P, the pressure columns P2 are simultaneously driven to compress and press the top end 1171 of the spring 117 downward, and the spring 117 is compressed downward from the position where it originally supported on the lower end surface 1122 of the screw head 112, so that the top end 1171 of the spring 117 is pressed into the accommodating space 123 of the sleeve 12, and then the retaining ring 13 is pressed downward. The other side (lower side) of the abutment portion 131A is moved upward (manually or with the aid of a jig and equipment), and the fulcrum A of the spring ring 13 is used as support again, so that the hook ends 1321 of the two hook arms 132A of the spring ring 13 extend toward the window 125 into the accommodating space 123 and are re-pressed and clamped on the top end 1171 of the spring 117. Since the upper side surfaces of the hook ends 1321 of the hook arms 132A abut against the upper edge 1251 of the window 125, they are also axially limited by the window 125 again, so that the spring returns to the compressed state in the sleeve, so as to facilitate the subsequent re-installation operation. The fixing element of the present invention can not only be used for the heat sink 2 assembled with the bare die type heat source 3, but also provide an opportunity for reassembly when the heat sink 2 needs to be reassembled or replaced.

1: Fixing unit 11: Screw 112: Screw head 1121: Upper end surface 1122: Lower end surface 113: External thread 114: Cutout 115: Retaining ring groove 116: Retaining ring 117: Spring 1171: Top end 1172: Bottom end 12: Sleeve 121: Upper end 122: Lower end 123: Accommodating space 124: Joint area 125: Window 1251: Upper edge 1252: Step part 13: Circlip 131: Abutment part 132: Hook arm assembly 132A: Hook arm 1321: Hook end P: Heavy work fixture P1: Head P2: Pressure column 2: Heat dissipation device 21: First side 22: Second side 23: Heating area 24: Perforation 3: Heat source 4: Fixing structure 5: Pressing fixture 51: Pressure extension part

Figure 1 is a schematic diagram of a known heat sink and a bare die combination. Figure 2 is a schematic diagram of a known heat sink and a bare die combination. Figure 3 is a three-dimensional combination diagram of a fixing element with a rework function of the present invention. Figure 4 is a three-dimensional exploded diagram of a fixing element with a rework function of the present invention. Figure 5 is a schematic diagram of an actuation of a fixing element with a rework function of the present invention. Figure 6 is a schematic diagram of an actuation of a fixing element with a rework function of the present invention. Figure 7 is a schematic diagram of an actuation of a fixing element with a rework function of the present invention.

1: Fixed unit

11: Screws

112: Screw head

1121: Upper end surface

1122: Lower end surface

113: External thread

114:Incision

115: Buckle ring storage slot

116: Buckle

117: Spring

1171: Top

1172: bottom

12: Sleeve

121: Top

122: Lower end

123: Storage space

124: Binding area

125: Window

13: Circlip

132:Hook arm set

132A: Hook arm

1321: Hook end

Claims (8)

A fixing element with a rework function is used to provide a heat sink and a bare die heat source for repeated installation and use. The fixing element with a rework function includes: A screw, with a spring sleeved on the outside, the upper and lower ends of the screw respectively having a screw head and a plurality of external threads, the screw head having two cutouts along the axial direction of the screw, the screw having a retaining ring receiving groove adjacent to the external threads, and the retaining ring receiving groove having a retaining ring, the spring having a top end and a bottom end, the bottom end abutting against the retaining ring; A sleeve, the sleeve has an upper end and a lower end in an open state, a containing space is provided between the upper and lower ends, the containing space is connected to the upper and lower ends respectively, the sleeve has a pair of windows near the upper end, the windows correspond to each other and are connected to the containing space, there is a coupling area between the lower edge of the window and the lower end of the sleeve, the sleeve is sleeved on the outside of the screw with a spring; A spring ring is sleeved on the joint area of the sleeve, and a hook arm group extends upward, the hook arm group has a pair of hook arms, the hook arms are respectively extended from the aforementioned window to press and clamp the top end of the spring to make the spring compressed; when the heat sink and the heat element are installed, the hook arm is operated to withdraw from the window to release the spring, thereby providing the synchronous and uniform downward pressure; when it is necessary to rework, a jig is extended from the two cutouts of the screw head to axially press the top end of the spring downward, so that the spring is compressed in the sleeve, and the hook arms are extended into the sleeve window to press the top end of the spring again, so that the spring returns to the compressed state. A fixing element with heavy-duty function as described in claim 1, wherein the screw head has an upper end face and a lower end face, and the cutouts penetrate the upper and lower end faces of the screw head at the same time. A fixing element with a reworking function as described in claim 1, wherein the windows have an upper edge, the upper surface of the hook end is against the upper edge, and the upper edge of the window provides axial limitation for the hook end. A fixing element with a rework function as described in claim 1, wherein the outer diameter of the coupling area is smaller than the outer diameter of the rest of the sleeve, and the lowermost side of the coupling area has a step portion, and the step portion can provide axial limitation for the retaining spring ring to prevent the retaining spring ring from excessively disengaging downward from the coupling area. As described in claim 1, the fixing element with a heavy-duty function, wherein the coupling area between the annular body of the retaining spring ring and the sleeve can be loosely fitted or tightly fitted. A fixing element with a rework function as described in claim 1, wherein the retaining spring ring has an abutment portion, the abutment portion is located on the upper surface of the retaining spring ring and is close to the outer edge of the upper surface of the retaining spring ring. As described in claim 1, the fixing element with heavy-duty function, wherein the fixture has a head, and at least two independently arranged pressure columns protrude from one end of the head, and the pressure columns can respectively correspond to the two incisions through which the screw head is penetrated. As described in claim 7, a fixing element with a heavy-duty function, wherein when the jig is subjected to downward pressure, the pressure columns simultaneously compress the top end of the spring downward, compressing the spring downward from the position where it was originally supported on the lower end surface of the screw head, so that the top end of the spring is pressed into the accommodating space of the sleeve.

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