GB2172433A - Decoupling capacitor and method of manufacture thereof - Google Patents
Decoupling capacitor and method of manufacture thereof Download PDFInfo
- Publication number
- GB2172433A GB2172433A GB08606291A GB8606291A GB2172433A GB 2172433 A GB2172433 A GB 2172433A GB 08606291 A GB08606291 A GB 08606291A GB 8606291 A GB8606291 A GB 8606291A GB 2172433 A GB2172433 A GB 2172433A
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- 239000003990 capacitor Substances 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000005538 encapsulation Methods 0.000 claims abstract description 15
- 239000002356 single layer Substances 0.000 claims abstract description 13
- 239000004020 conductor Substances 0.000 claims description 121
- 239000000463 material Substances 0.000 claims description 14
- 239000000853 adhesive Substances 0.000 claims description 7
- 230000001070 adhesive effect Effects 0.000 claims description 7
- 239000010410 layer Substances 0.000 claims description 7
- 229910010293 ceramic material Inorganic materials 0.000 claims description 4
- 238000000465 moulding Methods 0.000 abstract description 20
- 238000003780 insertion Methods 0.000 abstract description 14
- 239000003985 ceramic capacitor Substances 0.000 abstract description 9
- 239000000919 ceramic Substances 0.000 description 25
- 238000010276 construction Methods 0.000 description 6
- 230000037431 insertion Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 229910000679 solder Inorganic materials 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- -1 i.e. Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- 230000000063 preceeding effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/228—Terminals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/224—Housing; Encapsulation
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
- H05K1/023—Reduction of cross-talk, noise or electromagnetic interference using auxiliary mounted passive components or auxiliary substances
- H05K1/0231—Capacitors or dielectric substances
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
A decoupling capacitor and method of manufacture thereof are presented wherein the decoupling capacitor is formed from a lead frame which contains the four leads (18-24) of the capacitor (two of which are electrically inactive) on a single plane. The use of a lead frame automatically provides the dimensional tolerances necessary for encapsulation molding (34) of the decoupling capacitor. In a first embodiment, the decoupling capcitor is a hermetically sealed capacitive unit consisting of a single layer ceramic capacitor, active leads (18, 22) bonded to the capacitor and dummy pins (20, 24) for auto-insertion into printed boards. In a second embodiment, the decoupling capacitor is a hermetically sealed capacitive unit consisting of a multilayer monolithic ceramic capacitor (90) (for higher capacitance values in combination with other desirable properties as flat capacitance vs. temperature characteristics), active leads (64) bonded to the capacitor (90) and dummy pins (60) for auto-insertion into printed circuit boards. The capacitor is mounted on a conductive plate of the lead frame, and carries a second, parallel plate that contacts one of the active leads. Alternatively, the multilayer capacitor (90) sits on and between a pair of stepped conductive plates (52, 54). <IMAGE>
Description
SPECIFICATION
Decoupling capacitor and method of manufacture thereof
This invention relates to the field of decoupling capacitors for integrated circuits. More particularly, this invention relates to novel and improved decoupling capacitors, and methods of formation thereof wherein the capacitors are formed from a lead frame which contains the four leads of the capacitor (two of which of electrically inactive "dummy" pins) on a single plane. This lead frame construction permits the decoupling cacacitor to be subjected to encapsulation molding to form decoupling capacitors which are auto-insertable into printed circuit boards for use in conjunction with dual-in-line integrated circuits or other electronic components.
US patent 4,502,101 discloses a decoupling capacitor for an integrated circuit package. The decoupling capacitor of that prior patent is a thin rectangular chip of ceramic material which is metallized on opposite sides and has leads from the metallized coatings on opposite sides of the chip at two points adjacent a pair of diagonally opposed corners of the rectangularly shaped ceramic chip. The two leads are bent downwardly, and the decoupling capacitor assembly is encapsulated in a film of non-conductive material. In accordance with the teachings of that prior patent, the decoupling capacitor is dimensioned so as to be received in the space between the two rows of leads extending from a conventional dual-in-line integrated circuit.The two leads from the decoupling capacitor are plugged into a printed circuit board, with these leads from the capacitor being inserted into the printed circuit through holes to which the ground and power supply conductors are connected. The associated integrated circuit or other electronic component is then positioned over the capacitor and inserted into the board such that the power supply leads of the integrated circuit or other component will be positioned in the same through-holes of the printed circuit board in which the two capacitor leads have been inserted.
The diagonally located leads or pins on the decoupling capacitor of US patent 4,502,101 have resulted in a problem when it is desired to automatically insert the decoupling capacitors into the printed circuit board. Standard auto-insertion equipment is available for inserting integrated circuit elements into the printed circuit boards. The insertion heads on standard auto-insertion equipment grasp the integrated circuitaboutthe bent terminal pins or leads of the integrated circuit. Since there are two symmetric rows of pins on the integrated circuit element, the auto-insertion equipment can grasp the integrated circuit element symmetrically and stably for insertion.However, when insertion of the decoupling capacitor of prior US patent 4,502,101 is attempted with the same auto-insertion equipment, an unstable condition and misalignment results because of the fact that the decoupling capacitor, rather than having two symmetrical rows of pins, has only two pins at diagonally opposite corners of the rectangular capacitor. Because of the presence of only the two pins, the capacitor "cocks" in the insertion head with the result that misalignement occurs between the terminals of the capacitor in the corresponding holes on the printed circuit board.
Since it is extremely desirable to auto-insert the decoupling capacitors into the printed circuit boards, and since it is equally desirable to perform that auto-insertion with the same auto-insertion equipment used with the integrated circuit elements, a significant problem is encountered with the decoupling capacitor of the prior application, not from the standpoint of its electronic operability and effectiveness, but rather from the standpoint of adapting it to high volume assembly techniques.
A need also exists for a decoupling capacitor structure which is also auto-insertable, hermetically sealed, and capable of being manufactured by automated assembly processes.
US patent 4,475,143 discloses one approach to solving the above discussed auto-insertion problem by the incorporation of dummy or stabilizing pins in a decoupling capacitor assembly. US patents 4,491,895,4,494,169, 4,494,170,4,497,012, 4,511,951 and 4,532,572 present other constructions of and methods for forming decoupling capacitors with dummy pins or molded stabilizing lugs.
Presently, decoupling capacitors of the type hereinabove discussed and disclosed in the cited issued patents do not easily lend themselves to a molding encapsulating process, in part, because they are comprised of a two layer assembly, i.e., a top conductor with two leads and a bottom conductor with two leads, one lead from each conductor being an electrically inactive "dummy" lead. Unfortunately, currently used assembly methods of these decoupling capacitors do not provide the parallelism and perpendicularity tolerances between the two conductive layers required for a good molding encapsulation.It will be appreciated by those skilled in the art that a molded encapsulated package is important in providing environmental protection of the capacitor and to provide the dimensional stability, mass, weight, etc., needed for automatic insertion using adapted integrated circuit DIP inserters.
Additionally, and of equal importance, presently used manufacturing procedures for decoupling capacitors of the type hereinabove discussed (i.e., which include dummy leads) are not particularly well suited for incorporating multilayer monolithic ceramic capacitor chips as the capacitive element for the decoupling capacitor device. In effect then, this situation limits the capacitive element to be a single layer capacitor of limited obtainable capacitance per unit volume.
The above discussed and other problems of the prior art are overcome or substantially reduced by the new and improved decoupling capacitors of the present invention and the methods of manufacture thereof. The decoupling capacitor of the present invention is formed from a lead frame which contains the four leads of the capacitor (two of which are electrically inactive dummy leads) on a single plane.
The use of such a lead frame will automatically provide the dimensional tolerances for a good, efficient encapsulation molded decoupling capacitor package. The present invention thus presents constructions of and methods for forming improved decoupling capacitors which are hermetically sealed, auto-insertable and manufactured in a lead frame followed by an encapsulation molding process.
In accordance with a first embodiment of the method of the present invention, a bottom conductor and four leads are formed from a continuous strip of electrically conductive material. One of the leads is attached to the bottom conductor and the other three leads are isolated therefrom. A single layer ceramic chip and a top conductor are then placed on the bottom conductor and bonded together wherein the ceramic chip is sandwiched between the top and bottom conductors. One of the three electrically isolated (dummy) leads is then electrically connected to the top conductor via, for example, a bent tang, wherein two electrically active leads (one connected to each conductor) and two electrically inactive dummy leads will remain. Preferably, the dummy leads and active leads are respectively oppositely disposed from one another.Finally, the leads, ceramic capacitor and conductors are all encapsulated by a molding process with the leads extending through the encapsulating material.
Thereafter, the decoupling capacitor is swerved from the lead frame. The decoupling capacitor of the present invention will thus be both hermetically sealed and automatically insertable for use in conjunction with integrated circuit DIP inserter devices.
In accordance with a second embodiment of the method of the present invention, a pair of conductors, each having a lead connected thereto are formed from a continuous strip of electrically conductive material. A pair of dummy leads, each being associated with a conductor, but isolated therefrom, is also formed from the strip. Thereafter, a multilayer monolithic ceramic capacitor is placed between the two conductors (preferably on a shelf formed from the conductors). The multilayer capacitor includes first and second conductive end surfaces which are bonded respectively to each conductor. Thereafter, the leads, ceramic chip and conductors are all encapsulated by a molding process with the leads extending through the encapsulated material. Finally, the decoupling capacitor is severed from the lead frame.The decoupling capacitor of the present invention will thus be both hermetically sealed and automatically insertable for use in conjunction with integrated circuit DIP inserter devices.
The above discussed and other features and advantages of the present invention will be apparent to and understood by those skilled in the art from the following detailed description and drawings.
Referring now to the drawings, wherein like elements are numbered alike in the several Figures;
Figure lisa plan view of a lead frame used in forming the decoupling capacitor having a single layer ceramic chip therein in accordance with the present invention;
Figure 2 is a plan view of the lead frame of Figure 1 showing a first step in forming the decoupling capacitor of the present invention;
Figure 3 is a side elevation view of the lead frame of Figure 2;
Figure 4 is a plan view of the lead frame of Figure 1 showing a second step in forming the decoupling capacitor of the present invention;
Figure 5 is a side elevation view of the lead frame of Figure 4;
Figure 6 is a plan view of the lead frame of Figure 1 showing a third step in forming the decoupling capacitor of the present invention;
Figure 7 is a side elevation view of the lead frame of Figure 6;;
Figure 8 is a cross-sectional elevation view of a portion of the lead frame of Figure 6;
Figure 9 is a cross-sectional elevation view along the line 9-9 of Figure 10;
Figure 10 is a plan view of the decoupling capacitor of the present invention including a single layer ceramic chip therein;
Figure 11 is a side elevation view of the decoupling capacitor of Figure 10;
Figure 12 is an end view of the decoupling capacitor of Figure 10;
Figure 13 is a plan view of a lead frame used in forming a decoupling capacitor having a multilayer ceramic chip therein in accordance with the present invention;
Figure 14 is a side elevation view of the lead frame of Figure 13;
Figure 15 is a plan view of the lead frame of Figure 13 showing a first step in forming the multi layer ceramic chip decoupling capacitor of the present invention;;
Figure 16 is a side elevation view of the lead frame of Figure 15;
Figure 17 is a side elevation view of a multilayer chip decoupling capacitor in accordance with the present invention prior to encapsulation;
Figure 18A is an enlarged cross-sectional elevation view of a portion of the decoupling capacitor of
Figure 17;
Figure 18B is an enlarged cross-sectional elevation view of a portion of the decoupling capacitor of
Figure 17 showin an optional configuration;
Figure 19 is a cross-sectional elevation view of the decoupling capacitor of Figure 17 after encapsulation and along the line 19-19 of Figure 20;
Figure 20 is a plan view of a multilayer ceramic chip decoupling capacitor in accordance with the present invention and
Figure 21 is an end view of the multilayer chip decoupling capacitor of Figure 20.
The present invention represents constructions of and methods for forming improved decoupling capacitors which are hermetically sealed, autoinsertable and manufactured in a lead frame followed by an encapsulation molding process. Figures 1-12 relate to a process for forming an encapsulated decoupling capacitor having a planar single layer ceramic chip capacitor therein. Figures 13-21 relate to a processforforming an encapsulated decoupling capacitor from a lead frame having a multilayer ceramic chip capacitor therein.
Referring first to Figure 1, a lead frame used in accordance with the present invention is shown generally at 10. Lead frame 10 is a continuous planar strip of conductive material, i.e., copper, which is provided with openings along the respective side edges thereof for registration and transport. It will be appreciated that Figure 1 shows only a small portion of a lead frame which is suitable for forming a single decoupling capacitor in accordance with the present invention. It will further be appreciated that lead frame 10 is preferably a stamped part wherein all the components thereof are rigid. Thus, the desired lead frame configuration is formed by removing unwanted material from the strip of conductive material using any suitable and conventional technique.
Lead frame 10 includes a bottom or lower conductor 14 which has a generally rectangular configuration and is attached to the rest of the lead frame via four support bars 16.
Lead frame 10 further includes four leads or pins 18,20,22 and 24. At this point in the decoupling capacitor formation process, lead 18 is mechanically attached to bottom conductor 14 and is therefore an electrically active pin while the other leads 20, 22 and 24 are isolated from bottom conductor 14 and are therefore electrically inactive or dummy pins.
However, as will be discussed in more detail below, lead 22 which is diagonally across from electrically active lead 18will be transformed into an electrically active lead along with lead 18. An important feature of the present invention is that all four leads or pins 18,20,22 and 24 are in the same plane. Thus, as the leads are generated at the same time, necessary tolerances which affect the molding process (injection, transfer) can be provided.
Referring now to Figures 2 and 3, a single layer capacitive ceramic chip indicated at 26 (Figure 3) is positioned over bottom conductor 14 and attached thereto by a suitable adhesive to the conductor body. Capacitive ceramic chip 26 consists of a ceramic capacitor element, such as barium titanate, in the form of a flat, generally rectangular plate.
Ceramic chip 26 will include a top conductor or conductor cap 28 thereon which may be adhesively applied thereto; or may consist of a coating of conductive material on the ceramic chip 26. Ceramic chip 26 and top conductor 28 will be disposed over and cover all of the lower conductor 14 and portions of active pin tab 18 and dummy pin tab 20 (lead 20 being positioned directly opposite active pin 18 as shown in Figure 2). Note that the two dummy leads 22 and 24 do not come into contact with the capacitor chip 26. Preferably, dummy lead 20 (located opposite to active lead 18) will be electrically isolated from the chip by a suitable coating, i.e., solder mask, etc.
Still referring to Figures 2 and 3, dummy lead 22 which is located diagonally opposite active lead 18 will contact ceramic chip 26 via top conductor 28.
Top conductor 28 is adhesively attached to the ceramic chip and is provided with a bent tang portion 30 (see Figure 9) which provides electrical and mechanical attachment to dummy lead 22. This contact between the bent tang portion 30 of top conductor 28 and dummy lead 22 thus renders dummy lead 22 an electrically active lead similar two electrically active lead 18. It will be appreciated that attachment of bent tang 30 to lead 22 may be accomplished by solder, conductive adhesives, riveting, splining, welding, ultrasonic welding, or any suitable method. Alternatively, if a benttang portion is not provided on top conductor 28, wire bonding techniques can be used to render the required dummy lead 22 an active lead.It will be appreciated then, that at this point in the decoupling capacitor formation process, the partially assembled decoupling capacitor of the present invention will have two, diagonally opposite electrically active leads 18 and 22 and two diagonally opposite electrically inactive dummy leads 20 and 24.
Referring now to Figures 4 and 5, in the next step in forming the decoupling capacitor of the present invention, the support or tie bars 16 are removed.
These support bars hold the conductor body 14 in position during the several preceeding processes, i.e., attaching a top conductor and bonding or laminating the components together. As these support bars would protrude from the final molded package and interfere with the molding process, they are removed at this point in the procedure.
Turning now to Figure 6 thru 8, the lead frame 10 is shown after encapsulation molding and deflashing has taken place. The molding encapsulation identified at 32 may utilize any suitable and well known molding procedures. Note that no exposed conductive surfaces are left on the decoupling capacitor except for the two active leads 18 and 22 and the two dummy leads 20 and 24 protruding therefrom.
Molded encapsulating material 32 acts to hermetically seal and protect the various components of decoupling capacitor 34. Following molding, the decoupling capacitor preferably undergoes a deflashing process. Deflashing is a process that removes excess encapsulate material that may be attached to the package during molding. This excess material is usually prevalent at the mating surfaces of the mold. It will be appreciated that the lead frame assembly is turned over for proper pin orientation prior to the molding process.
After molding and deflashing, the decoupling capacitor in accordance with the present invention and now identified at 34 is severed from any remaining support structure identified in Figures 1-4 at 36,38, 40 and 42. In a preferred embodiment, at least a pair of standoffs or risers 44 and 46 are molded into the decoupling capacitorto set off the decoupling capacitor from a circuit board for cleaning and other purposes.
In Figures 10-12, the decoupling capacitor 34 is shown after being trimmed, and after leads 18,20,22 and 24 have been bent to their final and proper orientation. As mentioned, Figure 9 is a crosssectional elevation view detailing the manner in which the bent tang portion 30 of top conductor 28 forms an electrical and mechanical connection to lead 22 to transform the same from a dummy lead to an active lead.
In accordance with the decoupling capacitor of the present invention which is formed by the method shown in Figures 1-12, a novel lead frame 10 is utilized which provides the necessary dimensional tolerances for a good and efficient encapsulated molded decoupling capacitor package. As men tioned, the lead frame 10 contains the four leads of the capacitor on a single plane. The use of such a lead frame automatically provides the critical dimensional tolerances necessary for encapsulation molding of the decoupling capacitor. The final decoupling capacitor device will be both hermetically sealed and automatically insertable using adapted integrated circuit DIP inserters.
Turning nowto a discussion of Figures 13-21, another embodiment of the present invention is shown wherein multilayer monolithic ceramic chip capacitors (MLC's) are used in place of the thin flat single layer capacitive chips associated with the embodiment of Figures 1-12. In Figure 13, a lead frame which may be formed in the same manner as lead frame 10 (as discussed above) having holes 49 for alignement and transport is generally identified at 50. Lead frame 50 includes two conductor body portions 52 and 54 separated therebetween by an "H" shaped space or opening 56. Conductor 52 includes an electrically active pin or lead 58 integrally attached thereto and an electrically inactive dummy pin or lead 60 which is isolated therefrom by a space 62.Similarly, conductor 54 includes an electrically active pin or lead 64 which is integrally attached thereto and an electrically inactive dummy pin or lead 66 which is separated from conductor 54 by space 68 As was discussed with regard to lead frame 10 of Figures 1-12, lead frame 50 includes several support structures which support the conductors 52, 54 and leads 58, 60, 64, 66 to the frame during the various processes. These support structures include supports 70,72, 74 and 76 which act to hold conductors 52 and 54 in position on the lead frame; and supports 78,80,82 and 84 which provide support for the various leads 58, 64 and 66.
Referring now to Figures 15 and 16, a shelf is formed which is suitable for accepting and retaining a multilayer ceramic chip capacitor. This shelf is comprised of the two inwardly facing portions 86 and 88 of conductors 52 and 54 which are bent to form a support or shelf (see Figure 16). Next, a mu Itilayer ceramic capacitor 90 is attached to each conductor portion 86, 88 (shelf). Attachment can be made by solder paste or any other suitable well known method. Figure 1 8A is an enlarged view showing attachment between capacitor 90 and conductor portion 86. In an alternative embodiment shown in Figure 18B, the step of forming a shelf may be eliminated by providing the multilayer capacitor chip with 90 or other suitably angled tabs 92.It will be appreciated that any other suitable and well known structure may be used to effect connection between the multilayer capacitor and conductors 52 and 54, such as, for example, butt joints or tangs.
Preferably, multilayer ceramic capacitor 90 is of the commercially available type utilizing interleaved layers of ceramic 91 and metallization, with alternate layers of metal 94 and 96 connected to end plate electrodes 98 and 100, respectively, and fired to form a monolithic block. However, it will be appreciated that any other suitable multilayer ceramic chip construction may be utilized in accordance with the present invention.
Figures 19-21 show the multilayer ceramic chip decoupling capacitor after encapsulation molding and after the several support structures 70 thru 84 have been severed. The final decoupling capacitor construction generally identified at 102 thus includes a pair of electrically isolated dummy leads 60 and 66 and a pair of electrically active leads 58 and 63 which are integrally attached to conductors 52 and 54, respectively. In turn, conductors 52 and 54 are electrically attached to electrodes 98 and 100, respectively, of multilayer capacitor 90.The whole assembly is then provided with an encapsulating material 104 with only the two electrically active leads 58 and 64 and the two electrically inactive leads 60 and 66 protruding outwardly therefrom.
As in the single layer chip embodiment of Figures 1-12, the multilayer ceramic chip embodiment of
Figures 13-21 utilizes a lead frame 50 which provides all four leads 58,60,64 and 66 in a single plane. The use of this lead frame 50 automatically provides the dimensionally critical tolerances necessary for encapsulation molding of the decoupling capacitor 102. For many applications, decoupling capacitor 102 of Figures 13-21 may be preferred over decoupling capacitor 34 of Figure 1-12. This is because decoupling capacitor 102 utilizes a high capacitance multilayer monolithic ceramic chip capacitor 90.
Such a capacitor provides much higher capacitance values than are obtainable using convention planar single layer ceramic capacitors along with other desirable properties such as a flat capacitance vs.
temperature characteristic.
The embodiment of the present invention as shown in Figures 13-21 provide certain otherfeatures and advantages which may be preferable over the single layer capacitor embodiment of Figures 1-12. For example, unlike the method of forming the decoupling capacitor 34 of Figures 1 thru 12, decoupling capacitor 102 does not require a top conductor or conductor cap to be applied onto the capacitor chip. Also, no lamination of the top and bottom conductors to the capacitor chip is required with decoupling capacitor 102. It will thus be appreciated that the elimination of at least these two steps will provide decreased costs and production time in forming decoupling capacitor 102 (relative to forming decoupling capacitor 34).
Claims (46)
1. A method of making a capacitor, including the steps of:
removing unwanted material from a strip of electrically conductive material to define a first conductor having first active lead connected thereto and to define second, third and fourth leads isolated from said first conductor, said first, second, third and fourth leads being in the same plane,
placing a single layer capacitor element on said first conductor, said capacitor element having first and second conductive end surfaces, with said first conductive end surface being in electrical contact with said first conductor, said capacitor element substantially covering said first conductor and partially covering said first and second leads,
placing a second conductor on said capacitor element with said second conductive end thereof being in electrical contact with said second conduc tor,forming an electrical and mechanical connection between said second conductor and said third lead, bonding the above elements to form an assembly and encapsulating said assembly to enclose and seal all of said assemblyotherthan a portion of said first, second, third and fourth leads.
2. A method as claimed in claim 1, wherein said step of forming an electrical and mechanical connection between said second conductor and said third lead comprises the steps of:
providing a bent tang to a portion of said second conductor and
bonding said bent tang to said third lead.
3. A method as claimed in claim 1, wherein said step of removing unwanted material from said strip of electrically conductive material further includes the steps of:
forming support structure for supporting said first conductor in said conductive strip and
severing said support structure prior to the encapsulation step.
4. A method as claimed in claim 1, wherein said step of removing unwanted material from said strip of electrically conductive material further includes the steps of;
forming support structure for supporting said first, second, third and fourth leads in said conductive strip and
severing said support structure subsequent to the encapsulation step.
5. A method as claimed in claim 1, wherein said active leads are at a first pair of diagonally opposed locations and said dummy leads are at a second pair of diagonally opposed locations.
6. A method as claimed in claim 1, including bonding said first and second conductors to the first and second conductive end surfaces of the capacitor element with conductive adhesive.
7. A method as claimed in claim 1, including forming registration holes in said strip of electrically conductive material.
8. A method as claimed in claim 1, including forming at least one set-off on said encapsulated assembly.
9. A capacitor including:
a first electrical conductor
a second electrical conductor
a first active lead extending from said first conductor at a first position,
a second active lead extending from said second conductor at a second position,
means for electrically connecting said first or second active leads to said first or second conductors,
a pair of dummy leads, said dummy leads being electrically isolated from said first and second conductors, a first of said dummy leads extending from said first conductor at a third position, and the second of said dummy leads extending from said second conductor at a fourth position,
at least a portion of said first and second active leads and said pair of dummy leads being in the same plane,
a single layer capacitive element between said first and second conductors, said capacitive element having first and second electrically conductive end surfaces.
said first and second conductors and said capacitive element being bonded together, with said first conductor and said first conductive end surface being electrically connected and said second conductor and said second conductive end surface being electrically connected and
a mold encapsulating cover encapsulating said conductors and capacitive element, with said active dummy leads extending from said encapsulating cover at said first, second, third and fourth positions.
10. A capacitor as claimed in claim 9, wherein said means for electrically connecting said first or second active leads to said first or second conductors comprises:
a benttang in a portion of said first or second conductor, said benttang being electrically connected to said first or second active leads.
11. A capacitor as claimed in claim 10, wherein said bent tang is bonded to said first or second active leads with conductive adhesive.
12. A capacitor as claimed in claim 9, wherein said capacitor element is a ceramic material with a pair of conductive end surfaces.
13. A capacitor as claimed in claim 9, wherein said active leads are at a first pair of diagonally opposed locations and said dummy leads are at a second pair of diagonally opposed locations.
14. A capacitor as claimed in claim 9, including set-off means on said encapsulating cover.
15. A capacitor as claimed in claim 9, wherein one of said first or second active leads is integrally attached to one of said first or second conductors.
16. An array of decoupling capacitors positioned between a pair of edge strips from which a conductor and active and dummy leads of the capacitors are formed, each of said capacitors being in accordance with any one of claims 9 to 15.
17. A method of making a capacitor, including the steps of:
removing unwanted material from a strip of electrically conductive material to define a first conductor having a first active lead connected thereto and a second conductor having a second active lead connected thereto,
removing further unwanted material from said strip of electrically conductive material to define a first dummy lead associated with said first conductor, but electrically isolated therefrom, and a second dummy lead associated with said second conductor, but electrically isolated therefrom, said first and second active leads and said first and second dummy leads being in the same plane,
placing a multilayer capacitor element between said first and second conductors, said capacitor element having first and second conductive end surfaces, with said first conductive end surface being in electrical contact with said first conductor and said second conductive end surface being in electrical contact with said second conductor,
bonding the above elements to form an assembly with said first and second conductors and said
multilayer capacitor element bonded together and
encapsulating said assembly to enclose and seal all of said assembly other than a portion of said first and second active leads and said first and second dummy leads.
18. A method as claimed in claim 17, including the steps of:
forming a support means in said first and second conductors and
placing said multilayer capacitor element on said support means.
19. A method as claimed in claim 18, wherein said support means comprises a first bent portion in said first conductor and a second bent portion in said second conductor, said bent portions being inwardly facing and defining a shelf.
20. A method as claimed in claim 17, including the steps of:
providing a first tab to said first conductive end surface of said capacitor element and providing a
second tab to said second conductive end surface of said capacitor element and
bonding said first and second tabs to said first and
second conductors, respectively.
21. A method as claimed in claim 20, wherein in
said first and second tabs have a 90- bend.
22. A method as claimed in claim 17, wherein
said step of removing unwanted material from said
electrically conductive material further includesthe
steps of forming support structure for supporting said first
and second conductors in said conductive strip and
severing said support structure prior to the encap
sulating step.
23. A method as claimed in claim 17, wherein
said step of removing unwanted material from said
electrically conductive material further includes the
steps of:
forming support structure for supporting said first
and second leads and said dummy leads in said conductive strip and
severing said support structure subsequent to the
encapsulating step.
24. A method as claimed in claim 17, including
bonding said first and second conductive end surfaces of the capacitor element with conductive
adhesive.
25. A method as claimed in claim 17 including forming registration holes in said strip of electrically
conductive material.
26. A method as claimed in claim 17, wherein
said active leads are at a first pair of diagonally
opposed locations and said dummy leads are at a second pair of diagonally opposed locations,
27. A method as claimed in claim 17, wherein
said capacitive element is a ceramic material having
interleaved conductive layers with a pair of conductive end surfaces.
28. A method as claimed in claim 17, including the step of providing set-off means on said encapsu
lated assembly.
29. A capacitor including:
a first electrical conductor,
a second electrical conductor,
a first active lead extending from said first conductor at a first position, -a second active lead extending from said second conductor at a second position,
a first dummy lead associated with said first conductor, but electrically isolated therefrom at a third position,
a second dummy lead associated with said second conductor, but electrically isolated therefrom at a fourth position,
at least a portion of said first and second active leads and said first and second dummy leads being in the same plane,
a multilayer capacitive element between said first and second conductors, said capacitive element
having first and second conductive end surfaces, with said first conductive end surface being in
electrical contact with said first conductor and said second conductive end surface being in electrical contact with said second conductor and
a molded encapsulating coverencapsulating said conductors and capacitive element, with said active
and dummy leads extending from said encapsulat ins cover at said first, second, third and fourth
positions.
30. A capacitor as claimed in claim 29, including support means in said first and second conductors, said multilayer capacitive element being positioned on said support means.
31. A capacitor as claimed- in claim 30, wherein said support means comprises a first bent portion in said first conductor and a second bent portion in said second conductor, said bent portions being inwardly facing and defining a shelf,
32. A capacitor as claimed in claim 29, including a first tab means on said first conductive end surface of said capacitive element,
a second tab means on said second conductive end surface of said capacitive element and
said first and second tab means being bonded to said first and second conductors, respectively.
33. A capacitor as claimed claim 32 wherein said first and second tabs have a 90- bend.
34. A capacitor as claimed in claim 29, wherein said first and second conductive end surfaces of said capacitive element are bonded to said first and second conductors, respectively.
35. A capacitor as claimed in claim 34, wherein said bonding is accomplished by a conductive adhesive.
36. A capacitor as claimed in claim32, wherein said bonding is accomplished by a conductive adhesive.
37. A capacitor as claimed in claim 29, wherein said active leads are -at a first pair of diagonally opposed locations and said dummy leads are at a second pair of diagonally opposed locations.
38. A capacitor as claimed in claim 29, wherein said capacitive element is a ceramic material having interleaved conductive layers with a pair of conductive end surfaces.
39. A capacitor as claimed in claim 29, including set-off means on said encapsulated cover.
40. An array of capacitors positioned between a pair of edge strips from which a pairof conductors and active and dummy leads of the capacitors are formed, each of said capacitors being in accordance with any one of the claims 29 to 39.
41. A capacitor substantially as hereinbefore described and as illustrated in Figures 1 to 12 of the accompanying drawings.
42. An array of capacitors substantially as hereinbefore described and as illustrated in Figures 1 to 12 of the accompanying drawings.
43. A method of making a capacitor substantially as hereinbefore described and as illustrated in
Figures 1 to 1 2 of the accompanying drawings.
44. A capacitor substantially as hereinbefore described and as illustrated in Figures 13 to 21 of the accompanying drawings.
45. An array of capacitors substantially as hereinbefore described and as illustrated in Figures 13 to 21 of the accompanying drawings.
46. A method of making a capacitor subsstantially as herein before described and as illustrated in
Figures 13 to 21 of the accompanying drawings.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/711,478 US4622619A (en) | 1985-03-13 | 1985-03-13 | Decoupling capacitor and method of manufacture thereof |
US06/711,393 US4630170A (en) | 1985-03-13 | 1985-03-13 | Decoupling capacitor and method of manufacture thereof |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8606291D0 GB8606291D0 (en) | 1986-04-16 |
GB2172433A true GB2172433A (en) | 1986-09-17 |
GB2172433B GB2172433B (en) | 1989-06-21 |
Family
ID=27108630
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8606291A Expired GB2172433B (en) | 1985-03-13 | 1986-03-13 | Decoupling capacitor and method of manufacture thereof |
Country Status (5)
Country | Link |
---|---|
BE (1) | BE904407A (en) |
BR (1) | BR8601080A (en) |
DE (1) | DE3608412A1 (en) |
FR (1) | FR2582855B1 (en) |
GB (1) | GB2172433B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06334105A (en) * | 1993-05-24 | 1994-12-02 | Shinko Electric Ind Co Ltd | Multilayer lead frame |
DE102007014337B4 (en) * | 2007-03-26 | 2017-07-06 | Robert Bosch Gmbh | Method for equipping a contacting element with an electrical component and a contacting element with an electrical component |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3496435A (en) * | 1968-12-09 | 1970-02-17 | Corning Glass Works | Encapsulated electrical capacitor |
US3689804A (en) * | 1971-09-30 | 1972-09-05 | Nippon Denso Co | Hybrid circuit device |
US4521828A (en) * | 1982-12-23 | 1985-06-04 | At&T Technologies, Inc. | Component module for piggyback mounting on a circuit package having dual-in-line leads |
US4475143A (en) * | 1983-01-10 | 1984-10-02 | Rogers Corporation | Decoupling capacitor and method of manufacture thereof |
US4491895A (en) * | 1983-11-14 | 1985-01-01 | Rogers Corporation | Decoupling capacitor and method of manufacture thereof |
US4494169A (en) * | 1983-11-14 | 1985-01-15 | Rogers Corporation | Decoupling capacitor and method of manufacture thereof |
US4497012A (en) * | 1983-11-14 | 1985-01-29 | Rogers Corporation | Decoupling capacitor and method of manufacture thereof |
-
1986
- 1986-03-12 BE BE6/48202A patent/BE904407A/en not_active IP Right Cessation
- 1986-03-13 GB GB8606291A patent/GB2172433B/en not_active Expired
- 1986-03-13 BR BR8601080A patent/BR8601080A/en unknown
- 1986-03-13 DE DE19863608412 patent/DE3608412A1/en not_active Withdrawn
- 1986-03-13 FR FR8603565A patent/FR2582855B1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
GB2172433B (en) | 1989-06-21 |
FR2582855A1 (en) | 1986-12-05 |
BR8601080A (en) | 1986-11-25 |
BE904407A (en) | 1986-06-30 |
DE3608412A1 (en) | 1987-01-02 |
GB8606291D0 (en) | 1986-04-16 |
FR2582855B1 (en) | 1988-06-17 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930313 |