JP2000196280A - Adhesive clip for electromagnetic frequency interference shielding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shield an electronic circuit from electromagnetic interference by a clip comprising a mechanism, extending from a base engaged with a printed circuit board and a pickup tab such that a surface with which the head of a pick-up layer machine is engaged is connected to the base. SOLUTION: A clip 10 has an approximately square extension flat base 12 and pairs of oppositely facing V-shaped fingers 14a, 14b, 16a, 16b formed, an inverted L-shaped arm 18 extends vertically from the base 12 between the fingers 14a, 14b, 16a, 16b, a pick-up tab 18 a is formed on the arm 18, this tab 18a has a plane area for engaging with the head of a pick-up layout machine, the base 12 of the clip 10 is engaged with the surface of a printed circuit board and is inserted and fixed to the sidewall of an electromagnetic interference shield between the fingers 14a, 14b and 16a, 16b at a specified position on the top face of the printed circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to elements used during the manufacturing process of electronic circuit boards and, more particularly, to mounting a cover on a printed circuit board to shield the electronic circuit covered thereby from electromagnetic interference (EMI). It relates to a device for performing.

[0002]

BACKGROUND OF THE INVENTION As used herein, EMI encompasses not only radio frequency interference (RFI) but also electromagnetic pulses and fields, and EMI includes, for example,
It can be radiated by strong electromagnets, permanent magnets, motors, etc. As used herein, the term EMI encompasses all types of electromagnetic interference. EMI can severely impair the operation of sensitive electronics such as microprocessors.

[0003] Many electronic devices, such as microprocessors, emit radio frequency (RF) electromagnetic interference energy that can interfere with or harm the correct operation of other electronic devices and systems in the same environment. This is the reason for restrictions on airplanes, such as prohibition of laptop computer operation during takeoff and landing. Regulations on the operation of electronic devices that emit RF signals have been enacted to reduce the likelihood of damaging sensitive navigation and communication systems on airplanes. Thus, it has long been known to cover or shield electronics on a printed circuit (PC) board with an EMI shield. The shield typically includes a generally rectangular box or shroud made of cold rolled steel, copper or other material, having a lid and downwardly folded sidewalls. In many cases, the lid is provided with a number of ventilation holes to facilitate cooling of the electronic components contained therein. The aperture is usually sized to effectively block the RF signal passing through the aperture corresponding to the frequency of the RF signal. Conversely, the correct operation of many electronic devices requires that they not be exposed to certain levels of EMI from outside or external sources.

In the past, EMI shields have been manufactured in shapes suitable for mounting on conventional PC boards having through holes. In this way, these shields are provided with tabs and leads in positions corresponding to the corresponding through holes, and the tabs and leads are soldered in place to the shield covering the electronic device. Clips are also manufactured for insertion into the PC board through the holes, and the clips grip the vertical sidewalls of the EMI shield to hold it.

[0005] Electronic assemblies and manufacturing methods are moving to surface mount technology (SMT). According to this equipment mounting plan, PC boards typically do not have through holes, and individual electronics, shields, clips, and other devices have feet, leads or terminals, which are horizontal. And a terminal portion that protrudes from the terminal and fits the corresponding solder plate. During the melting process, the solder plate is heated by high intensity infrared radiation, etc.
Thus, the solder melts and an electrical and mechanical connection is achieved. During the assembly line manufacturing of surface mount printed PC boards, automatic pick and place machines are used to pick up equipment, connectors, clips and other equipment and deliver them to predetermined precise locations on the PC board. Often, electronics, clips and other equipment are supplied via tape and reel for pick-up by the pneumatic head of the pick-and-place machine. The head literally holds the device for sucking it up and transporting it to the PC board.

[0006] EMI shield clips conventionally have right-angled legs to facilitate surface mounting of the clip. For example, U.S. Patent No. 5,35 to Lange, Sr., assigned to Leader Tech Company in Tampa, Florida.
See 4,951. The patent discloses an EMI shield that includes a bottom fence having a number of mounting pins, which engage and support a movable rectangular top cover, thereby allowing access to the equipment. ing.

[0007] In one of the tape and reel types, electronics and other components are individually stored in pockets formed in the tape. The head of the pick and place machine must enter a pocket to remove the electronics or components.

Existing clips for securing the EMI shield to the PC board are not well-suited for use in tape and reel supply and subsequent correction and positioning by conventional pick and place machines.

It is an object of the present invention to provide a clip suitable for use.

[0010]

SUMMARY OF THE INVENTION The present invention provides a clip for securing a structure, such as an EMI shield, to a substrate, such as a PC board. The clip connects to a base that engages the surface of the PC board, a mechanism that extends from the base for engaging and gripping the side walls of the structure, and a base that provides a surface with which the head of the pick and place machine engages. And a pickup tab.

[0011]

1, a clip 10 is shown, which includes a structure for securing an EMI shield to a structure in the form of a PC board using SMT. The clip 10 is preferably manufactured through continuous stamping and bending of a sheet metal strip, which is described in further detail below. The metal may be inter-rolled steel, copper or any other metal that is stamped and easy to bend and solder quickly. The clip 10 includes a generally rectangular elongated flat base 12 and a pair of opposed V-shaped fingers 14a, 14b, 16a, 16b, the V-shaped fingers being generally perpendicular from the opposite end of the base 12. Is growing. An inverted L-shaped arm 18 extends vertically from base 12 between the pair of fingers. Arm 18 includes a generally horizontally extending pickup tab 18a or 18a '. Pickup tab 18a extends beyond base 12 and above.

The contour shapes of the fingers 14a and 14b and their relationship are exactly the same as the arrangement of the fingers 16a and 16b and their relationship. Therefore, only the latter needs to be shown. FIG.
5-8, the fingers 16a and 16b converge toward each other away from the base 12 before separating from each other. The tops of the fingers 16a and 16b are close but not touching each other. More specifically, the gap G in FIG.
Lies between the tops of two opposing fingers 16a and 16b. As can be seen in FIG.
When the vertical sidewalls of MI shield 22 are inserted through gap G between fingers 16a and 16b, fingers 16a and 16b move slightly apart to accommodate legs 20. Spacing G has a thickness that is slightly less than the thickness of the sidewall. Due to the elasticity of the metal finger portions 16a and 16b, the finger portions 16a and 16b rebound and press against the side wall 20.

When the side wall 20 is inserted between the fingers 16a and 16b, the pickup tab 18a is bent downward as shown in FIG. The distal end of the pick-up tab 18a meshes with a notch 24 at or below the lower end of the hole in the side wall 20 of the EMI shield. The side wall is thus locked in place in the clip 10 and if a shim (not shown) is inserted between the side wall 20 and the notch 24 so that the pick-up tab 18a does not come off the underline of the notch 24, It cannot be pulled out.

FIG. 2 shows a structure in the form of a PC board 26 which includes a microprocessing device 28 and a plurality of peripheral electronic devices 32, 34 and 36 mounted on the top surface of the PC board. I have it. Eight clips 10 of the type shown in FIG. 1 are mounted around a micro-processor 28 on the top surface of PC board 26. EMI shield 22-4
Each of the side walls 20 has fingers 14a, 14b, and 16a, 1
6b, which covers the microprocessor 28 and the equipment 30, 32, 34 and 36. This protects the microprocessor and other equipment EMI from external sources. In addition, the EMI sheet can be used to radiate the EMI emitted by the micro-processing device 28 and other devices into a PC.
Prevents leaving the board and interfering with peripheral electronics. The cover or lid 38 of the EMI shield 22 has a plurality of ventilation holes 40. The diameter of these holes 40 is selected for the wavelength of the RF radiation from within the shield,
It is configured such that RF radiation does not efficiently pass through the hole.

The base 12 of the clip 10 (FIG. 7) is provided with two opposing oval holes 42 and an intermediate circular hole. If desired, holes 45, shown in phantom in FIG. 1, are formed in pickup tab 18a to align with holes 44. A hole 46 is also formed in the L-shaped arm bent at the right angle, at which portion the arm is bent at a right angle.

Pickup tab 18a is an important feature of clip 10. The pick-up tab temporarily supports the lower edge of the side wall 20 of the EMI shield 22, when the edge is first finger 14a, 14b, 1 on the top of the clip.
It is supported between the expanded portions of 6a and 16b. As a result, as shown in FIG.
8a is pressed down to deform, allowing for instantaneous adjustment of the position of the shield 22 before fixing the side wall in place. It is important that the flared portions of the opposing fingers also provide a convenient guide for sidewall positioning. The pick-up tab 18a has a surface that is easily contacted and secured on the compressed air working head (not shown) of a conventional lay-down machine.

As best seen in FIG. 10, each clip 10 is stored in an open pocket 48 formed in a plastic transport tape 50. The plastic transport tape 50 has a series of holes 52 formed along one side edge so that it can be driven by a feeder (not shown) of a pick-up machine. Tape 50 typically has a top cover layer (not shown) adhered to hold clip 10 in place. The tape 50 stores the clip 10 therein and has a cover layer in place, and the tape is rewound from a supply reel 62 at a supply machine. The feeder strips off the top cover layer and the pneumatic head of the set-down machine uses the pick-up tab 1 of each clip 10.
8a is grasped and subsequently lifted from the corresponding pocket 48 of the tape 50 by suction. Clip 10 is P
It is moved to the vicinity of the C plate 26 and is placed on the solder plate 54 there.
After all clips 10, microprocessor 28 and other equipment 30, 32, 34, and 36 have been placed on the top surface of the PC board, they pass through a soldering station, where the solder where all equipment is placed is placed. The plate is heated by intense infrared or other heat sources. When the solder hardens, it melts to provide the required mechanical and electrical interconnections.

FIGS. 8 and 9 show successive steps in the manufacture of clip 10. FIG. A ribbon or web of a suitable sheet metal is fed to a series of presses to make a flat frame, such as 56 (FIG. 8), which is attached to a transport strip 60 by a flange 58.
Each frame 56 includes the opposing finger portions 14 fixed to the base 12.
a, 14b, 16a, and 16b. Moreover,
This pressing step forms holes 42, 44 and 46. The transport strip 60 is used to transport the frame 56 to various bending station positions to form the clip 10 as shown in FIG. FIG. 9 also shows a reel 62 from which a continuous web or ribbon 64 is drawn.
Is rewound, and the frame 56 is finally clip 1
Before being bent to zero, they are passed through various punching and stamping steps to form the frame 56, flange 58, and transport strip 60. The transport strip 60 is ultimately passed through a shear, which cuts the flange 58 from the frame 56 to separate the frame from the transport strip 60. The frame 56 is made of a plastic transport tape 50
It is mounted in the upper open pocket 48 (FIG. 10). A cover strip (not shown) is adhesively applied to the top layer of the transport tape 50 to hold the completed clip 10 in place. The transport tape 50 is wrapped around a reel 62 prior to shipment to a customer for mounting on a feeder of an automatic pick and place machine.

FIG. 11 shows how the clip 10 can be used for another EMI shield 22 ', with the vertical sidewall 2
0 'is a small recess or protrusion 6 instead of the engagement notch 24
6 is provided. When the side wall 20 'is inserted between fingers, such as 16a and 16b, of the clip 10, the side wall deflects the pick-up tab 18a downward as described above. However, in that case, the lower end of the pickup tab 18a is deformed to allow the protrusion 66 to pass therethrough, and EM
The protrusions 6 lock the I-shield 22 'in place.
6 is pressed.

The base 12 of the clip 10 provides stability for the clip when placed on a solder plate. The upwardly curved edges 12a and 12b (FIG. 3) connecting the base 12 and the fingers 14a, 14b, 16a, 16b help maximize the solder joint strength between the PC board 26 and the clip 10. The heights of the fingers 14a, 14b, 16a, 16b are selected so as to obtain an optimum right-angle spring force, maximum deformation and smooth introduction. The pickup tab 18a is contoured and dimensioned so that the head of the pick and place machine does not need to extend into the pocket 48 of the transport tape 50. Pickup tab 18a is located in the center of component 10 to provide balance. In this way, the contour of clip 10 is suitable for optimal placement speed and accuracy.

The pickup tab 18a has flexibility,
That is, when the side wall 20 of the EMI shield is inserted into the clip, it swings out of the passage. EMI shield 2
Notches 24 and protrusions 66 on the second side wall 20 are optional. The tip of the pickup tab 18a is the finger 14a, 1
4b, 16a, 16b provide some retention with the paired grips. However, holes 24 or protrusions 66
Is preferred, which eliminates the possibility of the shield 22 accidentally coming off the PC board due to vibration or shock. The pick-up tab 18a serves as a convenient platform for retaining the lower end of the side wall 20 of the EMI shield 22 slightly above the tip of the finger before being bent downward. This adjusts the lateral position of the EMI shield 22 before it is depressed, allowing it to lock in place. The minimum required insertion force is obtained.

The pickup tab 18a functions as a positioning device before assembly. Clips without this feature are limited to use with the pick and place device, which is a Z
It has the ability to move downward in the direction, i.e., the ability to descend to the bottom of the pocket 48 in the transport tape 50 to pick up parts. The clip 10 does not require the use of such a device, but can instead be used with a pick and place machine, in which the movement of the pneumatic head is limited to the X and Y directions.

In general, the present invention comprises, in a preferred embodiment, a metal clip which is soldered to a PC board via a solder plate, the PC board having an electromagnetic interference (EMI) shield on electronic equipment such as a microprocessor. It is for fixing. The clip is stamped from a metal plate and folded to provide a unitary structure, which is provided in the tape and supply reel pockets for automatic picking and placement on the PC plate. The clip includes two pairs of generally V-shaped fingers extending upwardly from the base and having opposing tops, the opposing tops having a gap therebetween having a dimension slightly less than the thickness of the EMI shield sidewall. One L-arm also extends upward from the base and has a horizontal pickup tab above the opposing top of the finger. The pick-up tab has a surface area for engaging the head of the pick and place machine, which does not need to penetrate the pocket of the transport tape to remove the clip. After the clip is secured to the PC board, the lower edge of the side wall of the EMI shield is first supported on the pickup tab between the extended upper portions of the opposing fingers. The shield and its side walls are then depressed down to deform and permanently bend the pickup tabs, so that their tips engage notches or protrusions in the side walls to lock the side walls in place. At the same time, the finger part expands to allow the side wall to enter therebetween, and is pressed to grip the side wall.

FIG. 12 shows another use of the clip 10, wherein the clip 10 has a different EM on the underside of the PC board 70.
Allowing the I-shield 68 to be secured, so that the clip 10 can grasp and hold the terminal or tab 72 of the shield 68 on the upper side of the PC board. More specifically, the PC board 70 has the through holes 7.
4 which allow the terminal 72 to extend through the hole and through the hole 42 in the base of the clip 10, so that the terminal extends between opposing fingers, such as 16a and 16b, and is gripped by them. obtain.

FIG. 13 shows another embodiment 7 of the clip of the present invention.
6 is shown. It is similar to clip 10 except that it has a pickup tab 18b that extends outwardly from clip base 78. This base has no holes. However, the pick-up tab 18b may include a hole 80 as indicated by the dashed line.

Another embodiment 76 of the clip shown in FIG. 13 is a single outwardly projecting pickup tab 18b.
Which can be gripped by the head of the pick and place machine. However, this clip 76 does not have a pick-up tab that is bent or deformed outward from its position by the side wall of the clip, and thus the pick-up tab 18b creates additional force for insertion of the side wall 20 of the shield 22. Absent.

Although embodiments of the novel clip for securing an EMI shield to a faceplate have been described, it will be apparent to those skilled in the art that our invention can be modified in both arrangement and detail construction. . Accordingly, the protection afforded to our invention should be limited only by the following claims.

[0028]

According to the present invention, the disadvantages of the conventional clip described above can be solved and a clip particularly suitable for use can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a preferred embodiment of the EMI obstruction shield clip of the present invention.

FIG. 2 is a perspective view of a PC board having a plurality of clips of the type shown in FIG.
The PC is mounted on the PC board to fix the shield, thereby surrounding a plurality of electronic devices mounted on the PC board.

FIG. 3 is an end view of the clip of FIG. 1;

FIG. 4 is an end view of FIG. 1 after the clip has received the sidewalls of the EMI shield.

FIG. 5 is a slightly reduced plan view of the clip of FIG. 1;

FIG. 6 is a slightly reduced side view of the clip of FIG. 1;

FIG. 7 is a slightly reduced bottom view of the clip of FIG. 1;

FIG. 8 shows one step in the continuous production of the clip of FIG.

FIG. 9 shows another example of the continuous production of the clip of FIG.
Shows two stages.

FIG. 10 illustrates how the clips of FIG. 1 are stored in pockets on a continuous tape reel for removal by a pneumatic head (not shown) of the removal and placement machine. In FIG. 10, a portion of the tape has been enlarged to show the details of storing the clip in a continuous tape pocket.

FIG. 11 shows the clip of FIG. 1 having a protrusion on the side wall;
FIG. 4 illustrates a method that can be used in a MI shield, where the protrusion is an alternative to a notch that provides a selectable locking feature.

FIG. 12 is an end view of the vertical cross section of the PC board and the clip of FIG. 1 surfaced on the top surface of the PC board, and an EMI shield is provided on the underside of the PC board by being secured to the clip through a hole The method is shown.

FIG. 13 is a perspective view of an alternative embodiment of the EMI shield clip of the present invention, the clip having an outwardly extending pickup arm, which does not require modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Clip 12 Base 14a, 14b Finger part 18 Arm 18a Pickup tab 20 Side wall 22 EMI shield 24 Notch 26 PC board 30 Electronic device 42, 44 Hole 54 Solder plate 66 Projection 72 Terminal 74 Through hole

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Joseph Jay Lynch US 92925 Iron Horse Drive 945, San Marcos, CA (72) Inventor Timothy Stephanie 55419 Minneapolis, MN, Nicoletto Minnesota, United States Avenue No. 5828 (72) Inventor Robert M. Bogarski, Encinitas, CA 92204, USA Cole Ranch Road No. 716 F-term (reference) 5E321 AA02 AA14 CC03 CC12 GG01 GG05

Claims (23)

[Claims] 1. A clip for mounting a structure on a substrate, comprising: a base for engaging a solder plate on a surface of a PC board; Means extending from the base for picking up; and a pick-up tab connected to the base to provide a surface for engaging the head of the pick and place machine. 2. The clip of claim 1, wherein the engagement gripping means includes at least one pair of opposing fingers extending from the base. 3. The clip of claim 1, wherein the pick-up tab is formed at an end of a generally L-shaped arm extending from the base. 4. The clip of claim 1, wherein the engagement gripping means includes two pairs of opposing fingers extending from the base. 5. The clip according to claim 1, wherein the base has a plurality of holes formed in the base. 6. The clip of claim 1, wherein the pick-up tab includes a pair of generally V-shaped opposing fingers extending from the base to form opposing tops, the opposing top being less than the thickness of the sidewall of the structure. It is possible to define a slightly smaller gap, into which the side wall can be inserted. 7. The clip of claim 6, wherein the pick-up tab is formed at an end of a generally L-shaped arm extending upwardly with respect to the base, and the pick-up tab extends substantially horizontally. 8. The clip of claim 1, wherein the engaging gripping means includes a first pair and a second pair of generally V-shaped opposing fingers, each pair extending upwardly from the base and facing each other. The opposing top defines a gap that is slightly less than the thickness of the sidewall of the structure, into which the sidewall can be inserted. 9. The clip of claim 8, wherein the pick-up tab is formed between a first pair and a second pair of V-shaped opposing fingers of the end of the generally L-shaped arm extending upwardly with respect to the base; The pickup tabs extend generally horizontally above the height of the opposing top. 10. The clip of claim 1, wherein the pick-up tab is formed on an end of a generally L-shaped arm extending upwardly with respect to the base, wherein the pick-up tab extends generally horizontally above the base and includes a structure. Is shaped and dimensioned to bend downward as it engages the pickup tab and moves downward relative to the pickup tab. 11. A clip for attaching a side wall of an EMI shield to a PC board, comprising:
A base for engaging the solder plate on the surface of the PC board;
A pair of flexible fingers extending from the base for receiving and clamping the side walls of the MI shield; and a tab connected to the base for initial engagement and support of the side wall edges. It provides a surface and can be deflected by the insertion of the sidewall between the fingers. 12. The clip of claim 11, wherein the tab is formed on an end of a generally L-shaped arm extending from the base. 13. The clip of claim 11, further including a pair of flexible fingers extending from a base for receiving and clamping the side walls of the EMI shield therebetween. 14. The clip according to claim 11, wherein the base, the finger and the tab are integrally formed of a folded metal plate. 15. The clip of claim 11, wherein the opposing fingers extend upwardly from the base in a generally V-shape to form opposing tops, the opposing tops having a gap slightly less than the thickness of the sidewall. A side wall can be inserted therein. 16. The clip of claim 11, wherein the tab is formed at the end of a generally L-shaped arm extending upwardly with respect to the base, and the tab extends generally horizontally. 17. The clip of claim 13, wherein the opposing fingers are generally V-shaped fingers, and each pair of fingers extends upwardly from the base to form opposing tops, and the opposing tops are sidewalls. With a gap that is slightly smaller than the thickness of the side wall, into which the side wall can be inserted. 18. The clip of claim 17, wherein the tab is formed between a first pair and a second pair of V-shaped opposing fingers of the end of the generally L-shaped arm extending upwardly with respect to the base. Extends generally horizontally above the height of the opposing top. 19. The clip of claim 11, wherein the tab is formed at an end of a generally L-shaped arm extending upwardly with respect to the base, wherein the tab extends generally horizontally above the base and the side wall engages the tab. The shape and dimensions are such that it curves downwardly as it moves downward relative to the tab. 20. An electronic assembly, comprising: a PC board; an electronic device mounted on a side of the PC board; a corresponding solder plate on a side of the PC board near the electronic device. A number of clips mounted thereon; a shield proximate to the electronics and attached to the PC board by clips; and at least a base soldered to the sides of the PC board and at least two sides of the side wall of the shield. It includes a pair of opposing fingers and an arm extending from the base and having a pickup tab. 21. The electronic assembly of claim 20, wherein the side wall of the shield has a notch, and the tip of the pickup tab fits into the notch when the side wall is inserted between the fingers to deform the tab. You. 22. The electronic assembly according to claim 20, wherein the side wall of the shield has a protrusion, and the tip of the pickup tab is fitted to the protrusion when the side wall is inserted between the fingers to deform the tab. . 23. An electronic assembly, comprising: a PC board; an electronic device mounted on a first side of the PC plate; and a plurality of PC boards located at a position close to the electronic device. A plurality of clips mounted on the corresponding solder plate on the first side of the PC board, each clip being mounted over the corresponding through hole; With a shield having a number and terminals, the terminals extend through corresponding through holes in the PC board and are held by corresponding clips.