EP1314196A1 - Method for making an integrated circuit capable of being surface-mounted and resulting circuit - Google Patents

Method for making an integrated circuit capable of being surface-mounted and resulting circuit

Info

Publication number
EP1314196A1
EP1314196A1 EP00953253A EP00953253A EP1314196A1 EP 1314196 A1 EP1314196 A1 EP 1314196A1 EP 00953253 A EP00953253 A EP 00953253A EP 00953253 A EP00953253 A EP 00953253A EP 1314196 A1 EP1314196 A1 EP 1314196A1
Authority
EP
European Patent Office
Prior art keywords
integrated circuit
pins
alloy
cell plate
cells
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00953253A
Other languages
German (de)
French (fr)
Inventor
Eric Thomson-CSF Propriété Intellectuelle PILAT
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Teledyne e2v Semiconductors SAS
Original Assignee
Atmel Grenoble SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atmel Grenoble SA filed Critical Atmel Grenoble SA
Publication of EP1314196A1 publication Critical patent/EP1314196A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3457—Solder materials or compositions; Methods of application thereof
    • H05K3/3485—Applying solder paste, slurry or powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
    • H01L21/4853—Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
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    • H01L23/13—Mountings, e.g. non-detachable insulating substrates characterised by the shape
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    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/498—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers
    • H01L23/49811—Additional leads joined to the metallisation on the insulating substrate, e.g. pins, bumps, wires, flat leads
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    • H01L23/49816—Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
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    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
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    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/341—Surface mounted components
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    • H—ELECTRICITY
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    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the invention relates to a method of manufacturing an integrated circuit for surface mounting of electronic cards. More specifically, the invention relates to the making of the electrical connections of the housing with the printed circuit of the electronic card.
  • connection commonly called by the English denomination of “Dual in line” or DIL has the drawback of being bulky and allows only realizations of the boxes with a limited number of outputs.
  • the rear face of the integrated circuit case produced in this PGA technology is equipped with the network of pins located under this rear face and perpendicular to this face. In this connection technology, the pins must be inserted in the electronic card where a significant loss of space.
  • FIG. 1 shows a partial sectional view of a ceramic housing 10 of an integrated circuit comprising a chip 12 transferred to the housing.
  • FIG. 1 shows the detail of one of the output connections of the box using a connector of the ball matrix or BGA type.
  • the chip 12 is turned over so as to present its electrical accesses situated on its active face, facing the interconnection substrate of the housing 10, in order to be soldered directly to the substrate of the housing.
  • the chip (not turned over) can be soldered to the housing by wire connections.
  • the chip 12 is connected by welds 14 to an internal connection 16 of the housing 10.
  • the internal connection 16 is connected to the outside of the housing, via the metal pads 18 located on the side of a rear face 19 of the housing 10.
  • Balls 20 of lead / tin alloy, intended to be soldered on the printed circuit (not shown in the figure) are soldered on the metal pads 18.
  • Breaking of the solder balls can occur on the one hand, at the time of soldering of the housing on the electronic card by the thermal shock which occurs during the melting of the ball 20 then its relatively rapid cooling, and on the other hand part during operation of the integrated circuit during variations in the ambient temperature.
  • This variation in ambient temperature can be very large and rapid (-55 ° C to + 150 ° C) in the case of military applications.
  • Another drawback of this connection technology of the bead matrix or BGA type is that the housing is difficult to recover to replace an expensive component in the event of a breakdown.
  • the 22 essentially consisting of a ceramic plate 24 having holes 26.
  • the holes 26 are arranged in the same distribution as that of the metal pads 18 of the connections of the housing.
  • an elongated ball 28 of welding is produced in each of the holes 26, the balls 28 protruding on either side of the ceramic plate 24.
  • the ceramic plate comprising the elongated balls 28 is disposed on the side of one of its faces, under the rear face 19 of the housing 10.
  • the other ends of the balls, protruding from the other side of the ceramic plate, intended to be soldered on an electronic card, are of greater height than the ends of the balls soldered on the housing.
  • the thermal stresses exerted on the balls of the housing equipped with the interposer once welded to the card, are thus distributed over the periphery of the ball.
  • a housing 30 is hollowed out of semi-spherical cavities 32 at the connection points of the housing.
  • a spherical ball 36 of welding is inserted in each of the cavities 32 covered with a layer of metal 34.
  • the thermal stresses are distributed over a larger surface without using an interposer requiring a mold for its production.
  • the balls used for soldering are usually made of an alloy comprising 93% lead and 7% tin which does not have good wettability.
  • the alloy contains 63% lead and 37% tin.
  • the invention provides a method of manufacturing an integrated circuit of the surface mountable type, first comprising the manufacture of a housing having one face rear and a network of connection pins, the network extending under this rear face perpendicular thereto, and then the formation at the end of each pin of a low melting point alloy ball surrounding this end and welded to it, characterized in that to form the ball at the end of each pin: - a filling plate, formed from the alloy material, is filled with a cell plate, the cells of which useful are distributed with the same distribution as the pins of the integrated circuit case;
  • the pins of the network of pins of the integrated circuit are inserted into the cells comprising the soldering cream, the integrated circuit being above the cell plate; - The cell plate is heated until the alloy melts;
  • the cell plate is cooled very quickly so as not to allow time for the liquid alloy to go up along the pins;
  • the cell plate is heated until the solder melts in the cells, producing gravity separation of the integrated circuit from the cell plate and the formation of solder balls at the ends of the pins, the alloy having sufficiently wetted the pins to remain attached to the pins and solidify quickly in the form of balls, as soon as the integrated circuit separates from the cell plate, the alloy does not have time to spread along the pins.
  • the invention also provides an integrated circuit of the surface-mountable type resulting from the manufacturing method according to the invention, comprising a housing having a rear face and a network of connection pins extending under the rear face perpendicular thereto, characterized in that the end of each pin has a low melting point alloy ball welded to the end of each pin surrounding this end.
  • the length of the pin end surrounded by the ball is substantially equal to the diameter of the ball. This results in particular embodiments such that in a first embodiment, the spindle end length surrounded by the ball is equal to the spindle length protruding from the rear face of the housing and in a second particular embodiment, the spindle length exceeding of the rear face of the housing is greater than the diameter of the ball. In other embodiments of the integrated circuit according to the invention, the length of the spindle end surrounded by the ball is less than the diameter of the ball.
  • the invention is applicable to integrated circuits made with either ceramic or plastic packages.
  • the manufacturing method according to the invention is particularly well suited to integrated circuits comprising pins of substantially constant section along the spindle and in particular when the pins are smooth, which is generally the case.
  • FIG. 3 already described, shows a sectional view of a housing of the prior art comprising solder balls arranged in cavities of the housing;
  • FIG. 4 shows an integrated circuit according to the invention comprising pins with solder balls.
  • FIG. 6 shows a detailed view of a pin of the integrated circuit of Figure 4 soldered on an electronic card.
  • FIG. 4 shows an integrated circuit 40 according to the invention comprising smooth connection pins 42 of substantially constant cross section along the pin, each of the pins having at its end a solder ball 44 surrounding this end.
  • the pins are made of nickel-plated ferronickel, then gilded in the case of ceramic boxes and in Kovar for plastic boxes.
  • the integrated circuit 40 can be produced according to different configurations of length of pins and positioning of the balls at the ends of the pins.
  • Figures 5a to 5d show the detail of one of the pins of the integrated circuit in different configurations.
  • FIG. 5a shows the detail of one of the pins of an embodiment of the integrated circuit 40 fitted with pins of length Lb larger than the diameter of the ball 44 welded at its end.
  • the length of the spindle end is substantially identical to the diameter D of the ball 44.
  • This embodiment includes the advantage of not producing the crushing of the solder balls at the time of their fusion, during the transfer of the integrated circuit to the card. Indeed, the balls are armed by their respective pins which pass through them over their entire diameter D.
  • the integrated circuit is equipped with short pins 46, the length of which is substantially equal to the diameter of the solder ball 44, the ball surrounding the entire pin.
  • FIG. 5b represents a view of one of the pins of such an integrated circuit. This configuration with short pins makes it possible to weld the box very close to the printed circuit of the card while avoiding crushing of the solder ball by the weight of the integrated circuit when it is transferred to the electronic card, the ball being armed, as in the case of the embodiment of FIG. 5a, over its entire diameter D.
  • the pin end length Le, surrounded by the ball 44, is less than the diameter of the ball.
  • FIG. 5c shows the detail of a configuration of the spindle 42 of FIG. 5a, in which the spindle end length Le surrounded by the ball 44 is less than the diameter D of the ball.
  • FIG. 5d shows the detail of a short pin 48 in a configuration different from that of FIG. 5b.
  • the length Lb of the spindle is less than the diameter D of the ball, the entire spindle 48 being surrounded by the ball 44.
  • the balls 44 of the different configurations of the pins can be made of an alloy comprising 63% lead and 37% tin which has only advantages, namely:
  • Figure 6 shows the detail of pin 42 of Figure 5a after welding of the integrated circuit 40 on an electronic card 50 having transfer metallizations 52.
  • the metallizations have on their surface solder 54 in an alloy generally having 63% lead and 37% tin.
  • Another advantage of this invention lies in the fact that even in the event of a break in the weld between the pin and the metallization of the card, the electrical contact will be ensured by the pin in contact with the metallization. Indeed, the pin which is soldered on the ceramic case is a very solid bond.
  • Figures 7, 8, 9 and 10 show the main phases of the manufacturing process according to the invention of the integrated circuit of Figure 4.
  • a first phase shown in Figure 7 one proceeds to the manufacture of an integrated circuit 60 surface mountable type, first comprising the manufacture of a housing having a rear face 62 and a network of smooth connection pins 64 extending under this rear face perpendicular thereto.
  • the length and diameter of the pins 64 will be chosen according to the constraints of the application and the reliability requirements.
  • the ends of the pins 64 can be tin-plated or dipped in flux or any other suitable chemical composition.
  • a solder cream 66 formed from the material of the alloy and the solvents is filled, a cell plate 68, the cells 70 of which are distributed on the plate with the same distribution as pins 64 of the integrated circuit box 60.
  • a second phase represented in FIG. 8 the ends of the pins 64 of the pin network of the integrated circuit 60 are inserted into the cells 70 comprising the soldering cream 66, the integrated circuit being above the cell plate, then the alloy is heated by passing the cell plate over a heating plate until the alloy melts and very quickly cools the cell plate so as not to allow time for the liquid alloy to go up along the pins producing the solidification of the alloy in the cells.
  • a third phase represented in FIG. 9, the integrated circuit 60 and the cell plate 68 secured to the integrated circuit by the alloy solidified in the cells are returned so as to put the cell plate above the integrated circuit.
  • the integrated circuit is suspended from the cell plate by its pins taken from the alloy solidified in the cells 70 of the plate.
  • a fourth phase shown in FIG. 10 the cell plate is heated until the alloy melts in the cells, producing the gravity separation of the integrated circuit from the cell plate and the formation of solder balls 72 at the ends of the pins.
  • the alloy has sufficiently wetted the pins to remain attached to the pins, solidifying rapidly in the form of balls, as soon as the integrated circuit is separated from the cell plate, the alloy having no time to spread over the pins.
  • the integrated circuit In this fourth phase, the integrated circuit, during the reflow of the alloy in the cells, falls by its own weight onto a receptacle 80 provided for this purpose located under the integrated circuit (see FIG. 10).
  • the distance between the integrated circuit and the receptacle is at least equal to the depth of the cells of the cell plate.
  • the order of the two operations consisting in inserting the ends of the pins 64 of the integrated circuit 60 in the cells 70 comprising the soldering cream 66 and in heating the alloy by passing the cell plate over a heating plate until the alloy melts, is indifferent and can be reversed without changing the result. It is therefore also possible, first to melt the soldering cream in the cells then insert the ends of the pins 64 of the integrated circuit 60 into the cells.
  • the solder paste formed for example from an alloy material comprising 63 % lead and 37% tin, can be made from any other alloy suitable for transferring components to the surface.
  • the cell plate 68 is made either of graphite or of titanium or of another type of material suitable for reflow.
  • the solder cream usually contains 50% lead / tin alloy and 50% fluid.
  • the ends of the pins are inserted into the cell plate up to the bottom of the cells, in order to obtain the pins of FIGS. 5a and 5b, the solder balls surrounding the pin end on a length substantially equal to the diameter D of the ball.
  • the alloy melted in the cells of the cell plate is obtained by placing calibrated alloy balls in a cell plate, the balls are melted and the pins of the network of pins of the integrated circuit in the cells comprising the molten alloy, the integrated circuit being above the cell plate, the following steps being the same as in the method described above either:
  • the cell plate is cooled very quickly so as not to allow time for the liquid alloy to rise along the connections;
  • the cell plate is heated until the solder melts in the cells, producing the gravity separation of the integrated circuit from the cell plate and the formation of solder balls 72 at the ends of the pins.
  • the order of the two operations consisting of melting the balls placed in the cells and inserting the pins of the network of pins of the integrated circuit into the cells comprising the molten alloy is indifferent and can therefore be reversed without changing the result. It is therefore also possible to insert the pins of the network of pins of the integrated circuit into the cells comprising the calibrated balls, then melt the balls.
  • the manufacturing process transforms an integrated circuit having a PGA type connection into BPGA technology, either English language "Bail Pin Grid Array”. Once the integrated circuit has been produced, it is mounted on its electronic card according to the same process as a conventional BGA.
  • the integrated circuit according to the invention makes it possible to obtain a high density of connections while guaranteeing better reliability, the ease of repairing the circuit and the possibility of removing calories between the connected substrates.

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Abstract

The invention concerns a method for making an integrated circuit (40) capable of being surface-mounted which consists in first making a housing with a rear face and an array of connection pins extending underneath said rear surface perpendicular thereto, and then in forming at the end of each pin a ball (44) of alloy with low melting point enclosing said end and welded thereto. The invention also concerns an integrated circuit (40) capable of being surface-mounted, comprising a housing with a rear surface and an array of connection pins, with substantially constant cross-section along the pin, extending underneath said rear surface perpendicular thereto. A ball (44) of alloy with low melting point is welded to the end of each pin (42) enclosing said end. The invention is applicable to surface-mounted integrated circuits.

Description

PROCEDE DE FABRICATION DE CIRCUIT INTEGRE DE TYPE MONTABLE EN SURFACE ET CIRCUIT ISSU DU PROCEDE METHOD FOR MANUFACTURING INTEGRATED CIRCUIT OF SURFACE MOUNTABLE TYPE AND CIRCUIT ARISING FROM THE METHOD
L'invention concerne un procédé de fabrication d'un circuit intégré pour montage en surface des cartes électroniques. Plus précisément l'invention concerne la réalisation des connexions électriques du boîtier avec le circuit imprimé de la carte électronique.The invention relates to a method of manufacturing an integrated circuit for surface mounting of electronic cards. More specifically, the invention relates to the making of the electrical connections of the housing with the printed circuit of the electronic card.
La complexité croissante des circuits électroniques intégrés, ainsi que l'augmentation du nombre de semi-conducteurs pouvant être intégrés dans une même puce, conduisent à une augmentation du nombre et de la densité de connexions de sorties des circuits intégrés. Les technologies de connexion en surface des circuits intégrés n'ont cessé d'évoluer dans ce sens. Certains boîtiers des circuits intégrés de l'état de l'art comportent des rangées de pattes disposées selon un pas régulier, perpendiculairement aux bords du circuit intégré, l'extrémité de chacune des pattes étant pliée à 90° par rapport à une face arrière du circuit intégré. Cette face arrière faisant face à une face de montage de la carte électronique sur laquelle le circuit intégré sera soudé. Le pliage des pattes à 90° permet leur soudure sur la face de montage de la carte. Ce type de connectique appelée couramment par la dénomination anglaise de « Dual in line » ou DIL comporte l'inconvénient d'être encombrante et ne permet que des réalisations des boîtiers avec un nombre de sorties limité. Les connexions utilisant un réseau de broches ou technologies de connexion connues sous dénomination anglaise de « Pin Grîd Array » ou PGA, sont utilisées depuis longtemps dans la micro-électronique. La face arrière du boîtier du circuit intégré réalisé dans cette technologie PGA est équipée du réseau de broches situées sous cette face arrière et perpendiculaires à cette face. Dans cette technologie de connexion, les broches doivent être insérées dans la carte électronique d'où une perte importante de place.The increasing complexity of integrated electronic circuits, as well as the increase in the number of semiconductors that can be integrated into the same chip, lead to an increase in the number and density of output connections of integrated circuits. Technologies for connection to the surface of integrated circuits have not stopped evolving in this direction. Some cases of integrated circuits of the state of the art have rows of tabs arranged in a regular pitch, perpendicular to the edges of the integrated circuit, the end of each of the tabs being bent at 90 ° relative to a rear face of the integrated circuit. This rear face facing a mounting face of the electronic card on which the integrated circuit will be soldered. Folding the tabs at 90 ° allows them to be welded to the mounting face of the card. This type of connection commonly called by the English denomination of “Dual in line” or DIL has the drawback of being bulky and allows only realizations of the boxes with a limited number of outputs. Connections using a network of pins or connection technologies known under the English name of “Pin Grid Array” or PGA, have been used for a long time in microelectronics. The rear face of the integrated circuit case produced in this PGA technology is equipped with the network of pins located under this rear face and perpendicular to this face. In this connection technology, the pins must be inserted in the electronic card where a significant loss of space.
Dans la technologie de circuits intégrés pour montage en surface (CMS), des pattes en forme de « J » ou « J-Lead » repliées sur les bords du boîtier du circuit intégré sont soudées sur le circuit imprimé. Dans les dernières générations des boîtiers des circuits intégrés, la connexion entre le circuit intégré et le circuit imprimé est réalisée par une matrice de billes en alliage plomb/étain. Cette technologie, connue sous la dénomination anglaise de « Bail Grid Array » ou BGA, permet une connectique très dense et plus courte verticalement, raccourcissant ainsi la longueur des connexions entre le circuit intégré et la carte électronique. Un des avantages de cette technologie est son meilleur comportement en fréquence.In integrated circuit technology for surface mounting (CMS), "J" or "J-Lead" shaped legs folded over the edges of the integrated circuit case are soldered to the printed circuit. In the latest generations of integrated circuit cases, the connection between the integrated circuit and the printed circuit is made by a matrix of lead / tin alloy balls. This technology, known under the English name of "Bail Grid Array" or BGA, allows very dense and shorter vertically connected connections, thus shortening the length of the connections between the integrated circuit and the electronic card. One of the advantages of this technology is its better frequency behavior.
A l'origine, la technologie BGA s'est développée pour obtenir un nombre important de broches de sortie sur les boîtiers avec un faible encombrement, mais de nos jours cette technologie est utilisée même pour des petites puces à faible nombre de sorties (par exemple, mémoires de 40 broches).Originally, BGA technology was developed to obtain a large number of output pins on boxes with a small footprint, but nowadays this technology is used even for small chips with low number of outputs (for example , 40-pin memories).
La figure 1 représente une vue partielle en coupe d'un boîtier en céramique 10 d'un circuit intégré comportant une puce 12 reportée sur le boîtier. La figure 1 montre le détail d'une des connexions de sortie du boîtier utilisant une connectique de type matrice à billes ou BGA .Figure 1 shows a partial sectional view of a ceramic housing 10 of an integrated circuit comprising a chip 12 transferred to the housing. FIG. 1 shows the detail of one of the output connections of the box using a connector of the ball matrix or BGA type.
Dans cet exemple de la figure 1, la puce 12 est retournée de façon à présenter ses accès électriques situés sur sa face active, face au substrat d'interconnexion du boîtier 10, afin d'être soudée directement sur le substrat du boîtier. Dans d'autres réalisations, la puce (non retournée) peut être soudée sur le boîtier par des connexions filaires.In this example of FIG. 1, the chip 12 is turned over so as to present its electrical accesses situated on its active face, facing the interconnection substrate of the housing 10, in order to be soldered directly to the substrate of the housing. In other embodiments, the chip (not turned over) can be soldered to the housing by wire connections.
La puce 12 est connectée par des soudures 14 à une connectique interne 16 du boîtier 10. La connectique interne 16 est reliée à l'extérieur du boîtier, par l'intermédiaire des plages métalliques 18 situées du côté d'une face arrière 19 du boîtier 10. Des billes 20 en alliage plomb/étain, destinées à être soudées sur le circuit imprimé (non représenté sur la figure) sont soudées sur les plages métalliques 18.The chip 12 is connected by welds 14 to an internal connection 16 of the housing 10. The internal connection 16 is connected to the outside of the housing, via the metal pads 18 located on the side of a rear face 19 of the housing 10. Balls 20 of lead / tin alloy, intended to be soldered on the printed circuit (not shown in the figure) are soldered on the metal pads 18.
Ce type de connectique BGA de la figure 1 présente des inconvénients importants. En effet lorsque les substrats du boîtier et celui de la carte sur laquelle est reporté le boîtier ont des coefficients de dilatation différents, par exemple boîtier en céramique et carte en résine époxy, la dilatation différentielle entre ces deux substrats, lors des variations de température, provoque des cassures des billes 20 de soudure. La hauteur des billes en alliage plomb/étain ne suffit pas à pallier ce problème et les soudures cassent relativement rapidement suivant les cycles thermiques.This type of BGA connection in Figure 1 has significant drawbacks. Indeed, when the substrates of the housing and that of the card on which the housing is transferred have different expansion coefficients, for example ceramic housing and epoxy resin card, the differential expansion between these two substrates, during temperature variations, causes the solder balls 20 to break. The height lead / tin alloy balls is not enough to overcome this problem and the solders break relatively quickly according to thermal cycles.
Les cassures des billes de soudure peuvent se produire d'une part, au moment de la soudure du boîtier sur la carte électronique par le choc thermique qui se produit lors de la fusion de la bille 20 puis son refroidissement relativement rapide, et d'autre part en cours de fonctionnement du circuit intégré lors des variations de la température ambiante. Cette variation de la température ambiante pouvant être très importante et rapide (-55°C à +150°C) dans le cas des applications militaires. Un autre inconvénient de cette technologie de connexion de type matrice de billes ou BGA est que le boîtier est difficilement récupérable pour remplacer un composant coûteux en cas de panne.Breaking of the solder balls can occur on the one hand, at the time of soldering of the housing on the electronic card by the thermal shock which occurs during the melting of the ball 20 then its relatively rapid cooling, and on the other hand part during operation of the integrated circuit during variations in the ambient temperature. This variation in ambient temperature can be very large and rapid (-55 ° C to + 150 ° C) in the case of military applications. Another drawback of this connection technology of the bead matrix or BGA type is that the housing is difficult to recover to replace an expensive component in the event of a breakdown.
Les fabricants de boîtiers proposent des solutions pour éviter les cassures des billes de soudure des boîtiers soudés sur une carte. La figure 2 montre une solution consistant à utiliser un interposeurEnclosure manufacturers offer solutions to avoid breakage of the solder balls of the soldered enclosures on a card. Figure 2 shows a solution of using an interposer
22 constitué essentiellement d'une plaque en céramique 24 comportant des trous 26. Les trous 26 sont disposés selon la même distribution que celle des plages métalliques 18 des connexions du boîtier.22 essentially consisting of a ceramic plate 24 having holes 26. The holes 26 are arranged in the same distribution as that of the metal pads 18 of the connections of the housing.
Avant montage de l'interposeur 22 sur le boîtier, une bille de forme allongée 28 de soudure est réalisée dans chacun des trous 26, les billes 28 dépassant de part et d'autre de la plaque de céramique 24.Before mounting the interposer 22 on the housing, an elongated ball 28 of welding is produced in each of the holes 26, the balls 28 protruding on either side of the ceramic plate 24.
La plaque de céramique comportant les billes allongées 28 est disposée du côté d'une de ses faces, sous la face arrière 19 du boîtier 10.The ceramic plate comprising the elongated balls 28 is disposed on the side of one of its faces, under the rear face 19 of the housing 10.
Les extrémités des billes, dépassant des trous d'un même côté de la plaque en céramique, sont soudées sur les plages métalliques 18 respectives des connexions du boîtier.The ends of the balls, protruding from the holes on the same side of the ceramic plate, are welded to the respective metal pads 18 of the connections of the housing.
Les autres extrémités des billes, dépassant de l'autre côté de la plaque de céramique, destinées à être soudées sur une carte électronique, sont de hauteur plus grande que les extrémités des billes soudées sur le boîtier. Les contraintes thermiques s'exerçant sur les billes du boîtier équipé de l'interposeur une fois soudées sur la carte, se trouvent ainsi réparties sur la périphérie de la bille.The other ends of the balls, protruding from the other side of the ceramic plate, intended to be soldered on an electronic card, are of greater height than the ends of the balls soldered on the housing. The thermal stresses exerted on the balls of the housing equipped with the interposer once welded to the card, are thus distributed over the periphery of the ball.
Dans le cas où l'on souhaite obtenir une hauteur de billes plus importante sous forme de colonne, afin de supporter des contraintes thermiques plus importantes, il est nécessaire d'utiliser un moule adapté. Une autre solution pour éviter la cassure des billes de soudure, est représentée par la figure 3.In the case where it is desired to obtain a greater height of beads in the form of a column, in order to withstand greater thermal stresses, it is necessary to use a suitable mold. Another solution to avoid breakage of the solder balls is shown in Figure 3.
Un boîtier 30 est creusé de cavités 32 semi-sphériques au niveau des points de connexions du boîtier. Dans chacune des cavités 32 recouvertes d'une couche de métal 34, est insérée une bille sphérique 36 de soudure. Dans ce type de connexion avec cavité, les contraintes thermiques sont réparties sur une plus grande surface sans utiliser un interposeur nécessitant un moule pour sa réalisation.A housing 30 is hollowed out of semi-spherical cavities 32 at the connection points of the housing. In each of the cavities 32 covered with a layer of metal 34, a spherical ball 36 of welding is inserted. In this type of connection with cavity, the thermal stresses are distributed over a larger surface without using an interposer requiring a mold for its production.
Dans le cas des boîtiers en céramique, les billes utilisées pour la soudure sont réalisées habituellement dans un alliage comportant 93% de plomb et 7% d'étain ne présentant pas une bonne mouillabilité. Dans le cas des boîtiers en plastique, l'alliage comporte 63% de plomb et 37% d'étain. On ne pourrait pas utiliser un alliage comportant 63% de plomb et 37% d'étain dans le cas des boîtiers en céramique car cela conduirait à un écrasement trop important des billes lors de la soudure du boîtier sur la carte.In the case of ceramic packages, the balls used for soldering are usually made of an alloy comprising 93% lead and 7% tin which does not have good wettability. In the case of plastic cases, the alloy contains 63% lead and 37% tin. We could not use an alloy comprising 63% lead and 37% tin in the case of ceramic boxes because this would lead to too much crushing of the balls when soldering the box to the card.
Les solutions actuelles au problème de cassure des soudures ne sont pas satisfaisantes en terme de coût et de performances. En particulier l'interposeur est une solution coûteuse. L'utilisation des colonnes limite le problème de cassure des billes mais cette solution, dans des applications militaires, reste néanmoins techniquement insuffisante.Current solutions to the problem of weld breakage are not satisfactory in terms of cost and performance. In particular, the interposer is an expensive solution. The use of columns limits the problem of breakage of the balls but this solution, in military applications, remains nevertheless technically insufficient.
Afin de pallier les problèmes de connexion des boîtiers des circuits intégrés de l'art antérieur, l'invention propose un procédé de fabrication d'un circuit intégré de type montable en surface, comprenant d'abord la fabrication d'un boîtier ayant une face arrière et un réseau de broches de connexion, le réseau s'étendant sous cette face arrière perpendiculairement à celle-ci, et ensuite la formation à l'extrémité de chaque broche d'une bille d'alliage à bas point de fusion entourant cette extrémité et soudée à celle-ci, caractérisé en ce que pour former la bille à l'extrémité de chaque broche : - on remplit d'une crème à souder, formée à partir du matériau de l'alliage, une plaque à alvéoles dont les alvéoles utiles se trouvent réparties avec la même distribution que les broches du boîtier du circuit intégré ;In order to overcome the problems of connection of the housings of the integrated circuits of the prior art, the invention provides a method of manufacturing an integrated circuit of the surface mountable type, first comprising the manufacture of a housing having one face rear and a network of connection pins, the network extending under this rear face perpendicular thereto, and then the formation at the end of each pin of a low melting point alloy ball surrounding this end and welded to it, characterized in that to form the ball at the end of each pin: - a filling plate, formed from the alloy material, is filled with a cell plate, the cells of which useful are distributed with the same distribution as the pins of the integrated circuit case;
- on insère les broches du réseau de broches du circuit intégré dans les alvéoles comportant la crème à souder, le circuit intégré étant au- dessus de la plaque à alvéoles ; - on chauffe la plaque à alvéoles jusqu'à la fusion de l'alliage ;- the pins of the network of pins of the integrated circuit are inserted into the cells comprising the soldering cream, the integrated circuit being above the cell plate; - The cell plate is heated until the alloy melts;
- on refroidit très rapidement la plaque à alvéoles afin de ne pas laisser le temps à l'alliage liquide de remonter le long des broches ;- the cell plate is cooled very quickly so as not to allow time for the liquid alloy to go up along the pins;
- on retourne alors le circuit intégré et la plaque d'alvéoles solidaire du circuit par l'alliage solidifié dans les alvéoles de façon à mettre la plaque à alvéoles au-dessus du circuit intégré, le circuit intégré étant suspendu à la plaque à alvéoles par ses broches prises dans l'alliage solidifié dans les alvéoles ;- The integrated circuit and the cell plate secured to the circuit by the alloy solidified in the cells are then returned so as to put the cell plate above the integrated circuit, the integrated circuit being suspended from the cell plate by its pins taken from the alloy solidified in the cells;
- on chauffe la plaque à alvéoles jusqu'à la fusion de la soudure dans les alvéoles produisant la séparation par gravité du circuit intégré de la plaque à alvéoles et la formation des billes de soudure aux extrémités des broches, l'alliage ayant suffisamment mouillé les broches pour rester accroché sur les broches et se solidifiant rapidement sous la forme de billes, dès la séparation du circuit intégré de la plaque à alvéoles, l'alliage n'ayant pas le temps de s'étaler le long des broches.- the cell plate is heated until the solder melts in the cells, producing gravity separation of the integrated circuit from the cell plate and the formation of solder balls at the ends of the pins, the alloy having sufficiently wetted the pins to remain attached to the pins and solidify quickly in the form of balls, as soon as the integrated circuit separates from the cell plate, the alloy does not have time to spread along the pins.
L'invention propose aussi un circuit intégré de type montable en surface issu du procédé de fabrication selon l'invention, comportant un boîtier ayant une face arrière et un réseau de broches de connexion s'étendant sous la face arrière perpendiculairement à celle-ci, caractérisé en ce que l'extrémité de chaque broche comporte une bille d'alliage à bas point de fusion soudée à l'extrémité de chaque broche en entourant cette extrémité.The invention also provides an integrated circuit of the surface-mountable type resulting from the manufacturing method according to the invention, comprising a housing having a rear face and a network of connection pins extending under the rear face perpendicular thereto, characterized in that the end of each pin has a low melting point alloy ball welded to the end of each pin surrounding this end.
Dans certaines réalisations du circuit intégré selon l'invention, la longueur d'extrémité de broche entourée par la bille est sensiblement égale au diamètre de la bille. Il en découle des réalisations particulières telles que dans une première réalisation, la longueur d'extrémité de broche entourée par la bille est égale à la longueur de broche dépassant de la face arrière du boîtier et dans une deuxième réalisation particulière, la longueur de broche dépassant de la face arrière du boîtier est supérieure au diamètre de la bille. Dans d'autres réalisations du circuit intégré selon l'invention, la longueur d'extrémité de broche entourée par la bille est inférieure au diamètre de la bille.In certain embodiments of the integrated circuit according to the invention, the length of the pin end surrounded by the ball is substantially equal to the diameter of the ball. This results in particular embodiments such that in a first embodiment, the spindle end length surrounded by the ball is equal to the spindle length protruding from the rear face of the housing and in a second particular embodiment, the spindle length exceeding of the rear face of the housing is greater than the diameter of the ball. In other embodiments of the integrated circuit according to the invention, the length of the spindle end surrounded by the ball is less than the diameter of the ball.
L'invention est applicable à des circuits intégrés réalisés avec des boîtiers soit en céramique, soit en plastique. Le procédé de fabrication selon l'invention est particulièrement bien adapté aux circuits intégrés comportant des broches de section sensiblement constante le long de la broche et notamment lorsque les broches sont lisses, ce qui est généralement le cas. D'autres caractéristiques et avantages de l'invention apparaîtront à la lecture de la description détaillée qui en est faite en référence aux dessins annexés dans lesquels :The invention is applicable to integrated circuits made with either ceramic or plastic packages. The manufacturing method according to the invention is particularly well suited to integrated circuits comprising pins of substantially constant section along the spindle and in particular when the pins are smooth, which is generally the case. Other characteristics and advantages of the invention will appear on reading the detailed description which is given with reference to the appended drawings in which:
- la figure 1 , déjà décrite, représente une vue partielle en coupe d'un boîtier en céramique de l'art antérieur ; - la figure 2, déjà décrite, montre une vue en coupe du boîtier de la figure 1 utilisant un interposeur ;- Figure 1, already described, shows a partial sectional view of a ceramic housing of the prior art; - Figure 2, already described, shows a sectional view of the housing of Figure 1 using an interposer;
- la figure 3, déjà décrite, montre une vue en coupe d'un boîtier de l'art antérieur comportant des billes de soudure disposées dans des cavités du boîtier ; - la figure 4, représente un circuit intégré selon l'invention comportant des broches avec des billes de soudure.- Figure 3, already described, shows a sectional view of a housing of the prior art comprising solder balls arranged in cavities of the housing; - Figure 4 shows an integrated circuit according to the invention comprising pins with solder balls.
- les figures 5a, 5b, 5c et 5d représentent des vues détaillées de différentes réalisations de broches du circuit intégré selon l'invention.- Figures 5a, 5b, 5c and 5d show detailed views of different embodiments of pins of the integrated circuit according to the invention.
- la figure 6, montre une vue de détail d'une broche du circuit intégré de la figure 4 soudée sur une carte électronique.- Figure 6 shows a detailed view of a pin of the integrated circuit of Figure 4 soldered on an electronic card.
- les figures 7, 8, 9 et 10 montrent différentes étapes de fabrication du circuit intégré selon l'invention.- Figures 7, 8, 9 and 10 show different stages of manufacturing the integrated circuit according to the invention.
La figure 4 montre un circuit intégré 40 selon l'invention comportant des broches de connexion 42 lisses de section sensiblement constante le long de la broche, chacune des broches ayant à son extrémité une bille 44 de soudure entourant cette extrémité. Les broches sont réalisées en ferronickel nickelé, puis doré dans le cas des boîtiers céramiques et en Kovar pour les boîtiers plastique.FIG. 4 shows an integrated circuit 40 according to the invention comprising smooth connection pins 42 of substantially constant cross section along the pin, each of the pins having at its end a solder ball 44 surrounding this end. The pins are made of nickel-plated ferronickel, then gilded in the case of ceramic boxes and in Kovar for plastic boxes.
Le circuit intégré 40 peut être réalisé selon différentes configurations de longueur de broches et de positionnement des billes aux extrémités des broches. Les figures 5a à 5d montrent le détail d'une des broches du circuit intégré selon différentes configurations.The integrated circuit 40 can be produced according to different configurations of length of pins and positioning of the balls at the ends of the pins. Figures 5a to 5d show the detail of one of the pins of the integrated circuit in different configurations.
La figure 5a montre le détail d'une des broches d'une réalisation du circuit intégré 40 équipé de broches de longueur Lb plus grande que le diamètre de la bille 44 soudée à son extrémité. Si l'on considère la partie de la broche Le entourée par la bille, que nous appellerons par la suite extrémité de broche, dans la réalisation de la figure 5a, la longueur de l'extrémité de broche est sensiblement identique au diamètre D de la bille 44. Cette réalisation comporte l'avantage de ne pas produire l'écrasement des billes de soudure au moment de leur fusion, lors du report du circuit intégré sur la carte. En effet, les billes sont armées par leurs broches respectives qui les traversent sur la totalité de leur diamètre D.FIG. 5a shows the detail of one of the pins of an embodiment of the integrated circuit 40 fitted with pins of length Lb larger than the diameter of the ball 44 welded at its end. If we consider the part of the spindle Le surrounded by the ball, which we will call hereinafter the spindle end, in the embodiment of FIG. 5a, the length of the spindle end is substantially identical to the diameter D of the ball 44. This embodiment includes the advantage of not producing the crushing of the solder balls at the time of their fusion, during the transfer of the integrated circuit to the card. Indeed, the balls are armed by their respective pins which pass through them over their entire diameter D.
Dans une autre réalisation, le circuit intégré est équipé de broches courtes 46, dont la longueur est sensiblement égale au diamètre de la bille 44 de soudure, la bille entourant la totalité de la broche. La figure 5b représente une vue d'une des broches d'un tel circuit intégré. Cette configuration avec des broches courtes, permet de souder le boîtier très près du circuit imprimé de la carte tout en évitant un écrasement de la bille de soudure par le poids du circuit intégré lors de son report sur la carte électronique, la bille étant armée, comme dans le cas de la réalisation de la figure 5a, sur la totalité de son diamètre D.In another embodiment, the integrated circuit is equipped with short pins 46, the length of which is substantially equal to the diameter of the solder ball 44, the ball surrounding the entire pin. FIG. 5b represents a view of one of the pins of such an integrated circuit. This configuration with short pins makes it possible to weld the box very close to the printed circuit of the card while avoiding crushing of the solder ball by the weight of the integrated circuit when it is transferred to the electronic card, the ball being armed, as in the case of the embodiment of FIG. 5a, over its entire diameter D.
Dans d'autres réalisations du circuit intégré la longueur d'extrémité de broche Le, entourée par la bille 44, est inférieure au diamètre de la bille.In other embodiments of the integrated circuit, the pin end length Le, surrounded by the ball 44, is less than the diameter of the ball.
La figure 5c montre le détail d'une configuration de la broche 42 de la figure 5a, dans laquelle la longueur d'extrémité de broche Le entourée par la bille 44 est inférieure au diamètre D de la bille.FIG. 5c shows the detail of a configuration of the spindle 42 of FIG. 5a, in which the spindle end length Le surrounded by the ball 44 is less than the diameter D of the ball.
La figure 5d montre le détail d'une broche courte 48 dans une configuration différente de celle de la figure 5b. Dans la configuration de la figure 5d, la longueur Lb de la broche est inférieure au diamètre D de la bille, la totalité de la broche 48 étant entourée par la bille 44.FIG. 5d shows the detail of a short pin 48 in a configuration different from that of FIG. 5b. In the configuration of FIG. 5d, the length Lb of the spindle is less than the diameter D of the ball, the entire spindle 48 being surrounded by the ball 44.
Les billes 44 des différentes configurations des broches, peuvent être réalisées dans un alliage comportant 63% de plomb et 37% d'étain qui ne présente que des avantages, à savoir:The balls 44 of the different configurations of the pins, can be made of an alloy comprising 63% lead and 37% tin which has only advantages, namely:
- point de fusion très bas ; - mouillabilité ;- very low melting point; - wettability;
- alliage identique à celui utilisé sur le circuit imprimé ; ou tout autre alliage adapté au report de composant en surface.- alloy identical to that used on the printed circuit; or any other alloy suitable for transferring a component to the surface.
La figure 6 montre le détail de la broche 42 de la figure 5a après soudure du circuit intégré 40 sur une carte électronique 50 ayant des métallisations de report 52. Les métallisations comportent sur leur surface de la soudure 54 dans un alliage ayant généralement 63% de plomb et 37% d'étain.Figure 6 shows the detail of pin 42 of Figure 5a after welding of the integrated circuit 40 on an electronic card 50 having transfer metallizations 52. The metallizations have on their surface solder 54 in an alloy generally having 63% lead and 37% tin.
Dans les réalisations des figures 5a et 5b, au moment du report du circuit intégré sur la carte, la soudure 54 située sur la métallisation 52 remonte vers l'extrémité de la broche 42. Il n'est pas, par conséquent, nécessaire d'écraser la bille de soudure 44 pour réaliser la soudure des broches sur la carte.In the embodiments of FIGS. 5a and 5b, when the integrated circuit is transferred to the card, the solder 54 located on the metallization 52 rises towards the end of the pin 42. It is therefore not necessary to crush the solder ball 44 to solder the pins on the board.
Un autre avantage de cette invention réside dans le fait que même en cas de rupture de la soudure entre la broche et la métallisation de la carte, le contact électrique sera assuré par la broche en contact sur la métallisation. En effet, la broche qui est brasée sur le boîtier en céramique est une liaison très solide.Another advantage of this invention lies in the fact that even in the event of a break in the weld between the pin and the metallization of the card, the electrical contact will be ensured by the pin in contact with the metallization. Indeed, the pin which is soldered on the ceramic case is a very solid bond.
Les figures 7, 8, 9 et 10 montrent les principales phases du procédé de fabrication selon l'invention du circuit intégré de la figure 4. Dans une première phase montrée à la figure 7, on procède à la fabrication d'un circuit intégré 60 de type montable en surface, comprenant d'abord la fabrication d'un boîtier ayant une face arrière 62 et un réseau de broches 64 de connexion lisses s'étendant sous cette face arrière perpendiculairement à celle-ci. La longueur et le diamètre des broches 64 seront choisis en fonction des contraintes de l'application et des exigences en matière de fiabilité.Figures 7, 8, 9 and 10 show the main phases of the manufacturing process according to the invention of the integrated circuit of Figure 4. In a first phase shown in Figure 7, one proceeds to the manufacture of an integrated circuit 60 surface mountable type, first comprising the manufacture of a housing having a rear face 62 and a network of smooth connection pins 64 extending under this rear face perpendicular thereto. The length and diameter of the pins 64 will be chosen according to the constraints of the application and the reliability requirements.
Suivant l'état de surface du circuit intégré 60 en technologie PGA, on peut étamer ou tremper les extrémités des broches 64 dans du flux ou toute autre composition chimique adaptée.Depending on the surface condition of the integrated circuit 60 in PGA technology, the ends of the pins 64 can be tin-plated or dipped in flux or any other suitable chemical composition.
Dans la première phase représentée à la figure 7, on remplit d'une crème à souder 66 formée à partir du matériau de l'alliage et des solvants, une plaque 68 à alvéoles, dont les alvéoles 70 se trouvent réparties sur la plaque avec la même distribution que les broches 64 du boîtier du circuit intégré 60.In the first phase shown in FIG. 7, a solder cream 66 formed from the material of the alloy and the solvents is filled, a cell plate 68, the cells 70 of which are distributed on the plate with the same distribution as pins 64 of the integrated circuit box 60.
Dans une deuxième phase représentée à la figure 8, on insère les extrémités des broches 64 du réseau de broches du circuit intégré 60 dans les alvéoles 70 comportant la crème à souder 66, le circuit intégré étant au- dessus de la plaque à alvéoles, puis on chauffe l'alliage en passant la plaque à alvéoles sur une plaque chauffante jusqu'à la fusion de l'alliage et on refroidit très rapidement la plaque à alvéoles afin de ne pas laisser le temps à l'alliage liquide de remonter le long des broches produisant la solidification de l'alliage dans les alvéoles.In a second phase represented in FIG. 8, the ends of the pins 64 of the pin network of the integrated circuit 60 are inserted into the cells 70 comprising the soldering cream 66, the integrated circuit being above the cell plate, then the alloy is heated by passing the cell plate over a heating plate until the alloy melts and very quickly cools the cell plate so as not to allow time for the liquid alloy to go up along the pins producing the solidification of the alloy in the cells.
Dans une troisième phase, représentée à la figure 9, on retourne le circuit intégré 60 et la plaque à alvéoles 68 solidaire du circuit intégré par l'alliage solidifié dans les alvéoles de façon à mettre la plaque à alvéoles au- dessus du circuit intégré. Dans cette phase, le circuit intégré est suspendu à la plaque à alvéoles par ses broches prises dans l'alliage solidifié dans les alvéoles 70 de la plaque. Dans une quatrième phase, représentée à la figure 10, on chauffe la plaque à alvéoles jusqu'à la fusion de l'alliage dans les alvéoles produisant la séparation par gravité du circuit intégré de la plaque à alvéoles et la formation des billes 72 de soudure aux extrémités des broches. L'alliage a suffisamment mouillé les broches pour rester accroché sur les broches en se solidifiant rapidement sous la forme de billes, dès la séparation du circuit intégré de la plaque à alvéoles, l'alliage n'ayant pas le temps de s'étaler sur les broches. Dans cette quatrième phase, le circuit intégré, lors de la refusion de l'alliage dans les alvéoles, tombe par son propre poids sur un réceptacle 80 prévu à cet effet situé sous le circuit intégré (voir figure 10). La distance entre le circuit intégré et le réceptacle est au minimum égal à la profondeur des alvéoles de la plaque à alvéoles.In a third phase, represented in FIG. 9, the integrated circuit 60 and the cell plate 68 secured to the integrated circuit by the alloy solidified in the cells are returned so as to put the cell plate above the integrated circuit. In this phase, the integrated circuit is suspended from the cell plate by its pins taken from the alloy solidified in the cells 70 of the plate. In a fourth phase, shown in FIG. 10, the cell plate is heated until the alloy melts in the cells, producing the gravity separation of the integrated circuit from the cell plate and the formation of solder balls 72 at the ends of the pins. The alloy has sufficiently wetted the pins to remain attached to the pins, solidifying rapidly in the form of balls, as soon as the integrated circuit is separated from the cell plate, the alloy having no time to spread over the pins. In this fourth phase, the integrated circuit, during the reflow of the alloy in the cells, falls by its own weight onto a receptacle 80 provided for this purpose located under the integrated circuit (see FIG. 10). The distance between the integrated circuit and the receptacle is at least equal to the depth of the cells of the cell plate.
Il est à remarquer que dans la deuxième phase du procédé de fabrication représentée à la figure 8, l'ordre des deux opérations, consistant à insérer les extrémités des broches 64 du circuit intégré 60 dans les alvéoles 70 comportant la crème à souder 66 et à chauffer l'alliage en passant la plaque à alvéoles sur une plaque chauffante jusqu'à la fusion de l'alliage, est indiffèrent et peut être inversé sans changement du résultat. On peut donc aussi, d'abord faire fondre la crème à souder dans les alvéoles puis insérer les extrémités des broches 64 du circuit intégré 60 dans les alvéoles La pâte à souder, formée par exemple à partir d'un matériau d'alliage comportant 63% de plomb et 37% d'étain, peut être réalisée à partir de tout autre alliage adapté au report des composants en surface.It should be noted that in the second phase of the manufacturing process represented in FIG. 8, the order of the two operations, consisting in inserting the ends of the pins 64 of the integrated circuit 60 in the cells 70 comprising the soldering cream 66 and in heating the alloy by passing the cell plate over a heating plate until the alloy melts, is indifferent and can be reversed without changing the result. It is therefore also possible, first to melt the soldering cream in the cells then insert the ends of the pins 64 of the integrated circuit 60 into the cells The solder paste, formed for example from an alloy material comprising 63 % lead and 37% tin, can be made from any other alloy suitable for transferring components to the surface.
Cette technologie de mise en place des billes de soudure aux extrémités des broches est très bon marché et ne nécessite pas de machine à positionner les billes préformées. La plaque 68 à alvéoles est réalisée, soit en graphite soit en titane ou dans un autre type de matériau adapté à la refusion. La crème à souder comporte habituellement 50% d'alliage plomb/étain et 50% de fluide.This technology of placing the solder balls at the ends of the pins is very inexpensive and does not require a machine for positioning the preformed balls. The cell plate 68 is made either of graphite or of titanium or of another type of material suitable for reflow. The solder cream usually contains 50% lead / tin alloy and 50% fluid.
En général, dans le procédé de fabrication, les extrémités des broches sont insérées dans la plaque à alvéoles jusqu'au fond des alvéoles, afin d'obtenir les broches des figures 5a et 5b, les billes de soudure entourant l'extrémité de broche sur une longueur sensiblement égale au diamètre D de la bille.In general, in the manufacturing process, the ends of the pins are inserted into the cell plate up to the bottom of the cells, in order to obtain the pins of FIGS. 5a and 5b, the solder balls surrounding the pin end on a length substantially equal to the diameter D of the ball.
Dans une variante du procédé de fabrication du circuit intégré, l'alliage fondu dans les alvéoles de la plaque à alvéoles est obtenu en plaçant des billes d'alliage calibrées dans une plaque à alvéoles, on fait fondre les billes et on insère les broches du réseau de broches du circuit intégré dans les alvéoles comportant l'alliage fondu, le circuit intégré étant au-dessus de la plaque à alvéoles, les étapes suivantes étant les mêmes que dans le procédé décrit précédemment soit :In a variant of the integrated circuit manufacturing process, the alloy melted in the cells of the cell plate is obtained by placing calibrated alloy balls in a cell plate, the balls are melted and the pins of the network of pins of the integrated circuit in the cells comprising the molten alloy, the integrated circuit being above the cell plate, the following steps being the same as in the method described above either:
- on refroidit très rapidement la plaque à alvéoles afin de ne pas laisser le temps à l'alliage liquide de remonter le long des connexions ;- the cell plate is cooled very quickly so as not to allow time for the liquid alloy to rise along the connections;
- on retourne alors le circuit intégré et la plaque d'alvéoles solidaire du circuit par l'alliage solidifié dans les alvéoles de façon à mettre la plaque à alvéoles au-dessus du circuit intégré, le circuit intégré étant suspendu à la plaque à alvéoles par ses broches prises dans l'alliage solidifié dans les alvéoles ;- The integrated circuit and the cell plate secured to the circuit by the alloy solidified in the cells are then returned so as to put the cell plate above the integrated circuit, the integrated circuit being suspended from the cell plate by its pins taken from the alloy solidified in the cells;
- on chauffe la plaque à alvéoles jusqu'à la fusion de la soudure dans les alvéoles produisant la séparation par gravité du circuit intégré de la plaque à alvéoles et la formation des billes 72 de soudure aux extrémités des broches.- The cell plate is heated until the solder melts in the cells, producing the gravity separation of the integrated circuit from the cell plate and the formation of solder balls 72 at the ends of the pins.
Il est à remarquer que dans cette variante du procédé de fabrication, l'ordre des deux opérations consistant à faire fondre les billes placée dans les alvéoles et à insérer les broches du réseau de broches du circuit intégré dans les alvéoles comportant l'alliage fondu est indiffèrent et peut donc être inversé sans changement du résultat. On peut donc aussi, insérer les broches du réseau de broches du circuit intégré dans les alvéoles comportant les billes calibrées, puis faire fondre les billes.It should be noted that in this variant of the manufacturing process, the order of the two operations consisting of melting the balls placed in the cells and inserting the pins of the network of pins of the integrated circuit into the cells comprising the molten alloy is indifferent and can therefore be reversed without changing the result. It is therefore also possible to insert the pins of the network of pins of the integrated circuit into the cells comprising the calibrated balls, then melt the balls.
Le procédé de fabrication, selon l'invention, transforme un circuit intégré ayant une connectique de type PGA en technologie BPGA soit en langue anglaise « Bail Pin Grid Array ». Une fois le circuit intégré réalisé, on le monte sur sa carte électronique selon le même procédé qu'un BGA classique.The manufacturing process, according to the invention, transforms an integrated circuit having a PGA type connection into BPGA technology, either English language "Bail Pin Grid Array". Once the integrated circuit has been produced, it is mounted on its electronic card according to the same process as a conventional BGA.
Le circuit intégré selon l'invention permet d'obtenir une grande densité de connexions tout en garantissant une meilleure fiabilité, la facilité de réparation du circuit et la possibilité d'évacuer des calories entre les substrats connectés. The integrated circuit according to the invention makes it possible to obtain a high density of connections while guaranteeing better reliability, the ease of repairing the circuit and the possibility of removing calories between the connected substrates.

Claims

REVENDICATIONS
1. Procédé de fabrication d'un circuit intégré (40, 60) de type montable en surface, comprenant d'abord, la fabrication d'un boîtier ayant une face arrière (62) et un réseau de broches de connexion, le réseau s'étendant sous cette face arrière perpendiculairement à celle-ci, et ensuite la formation à l'extrémité de chaque broche (42, 64) d'une bille (44, 72) d'alliage à bas point de fusion entourant cette extrémité et soudée à celle-ci, caractérisé en ce que, pour former la bille à l'extrémité de chaque broche :1. A method of manufacturing an integrated circuit (40, 60) of surface mountable type, comprising first, the manufacture of a housing having a rear face (62) and a network of connection pins, the network s 'extending below this rear face perpendicular thereto, and then forming at the end of each pin (42, 64) a ball (44, 72) of low-melting alloy surrounding this end and welded to it, characterized in that, to form the ball at the end of each pin:
- on remplit d'une crème à souder (66), formée à partir du matériau de l'alliage, une plaque (68) à alvéoles dont les alvéoles (70) utiles se trouvent réparties avec la même distribution que les broches (64) du boîtier du circuit intégré (60) ; - on insère les broches (64) du réseau de broches du circuit intégré (60) dans les alvéoles (70) comportant la crème à souder (66), le circuit intégré étant au-dessus de ta plaque à alvéoles ;- A solder cream (66) formed from the alloy material is filled with a cell plate (68), the useful cells (70) of which are distributed with the same distribution as the pins (64) the integrated circuit housing (60); - the pins (64) of the network of pins of the integrated circuit (60) are inserted into the cells (70) comprising the soldering cream (66), the integrated circuit being above your cell plate;
- on chauffe la plaque à alvéoles jusqu'à la fusion de l'alliage ;- The cell plate is heated until the alloy melts;
- on refroidit très rapidement la plaque à alvéoles afin de ne pas laisser le temps à l'alliage liquide de remonter le long des broches ;- the cell plate is cooled very quickly so as not to allow time for the liquid alloy to go up along the pins;
- on retourne alors le circuit intégré et la plaque d'alvéoles solidaire du circuit par l'alliage solidifié dans les alvéoles de façon à mettre la plaque (68) à alvéoles au-dessus du circuit intégré, le circuit intégré étant suspendu à la plaque à alvéoles par ses broches prises dans l'alliage solidifié dans les alvéoles ;- The integrated circuit and the cell plate secured to the circuit are then returned by the alloy solidified in the cells so as to place the cell plate (68) above the integrated circuit, the integrated circuit being suspended from the plate with cells by its pins taken from the alloy solidified in the cells;
- on chauffe la plaque (68) à alvéoles jusqu'à la fusion de la soudure dans les alvéoles (70) produisant la séparation par gravité du circuit intégré (60) de la plaque à alvéoles et la formation des billes de soudure (72) aux extrémités des broches, l'alliage ayant suffisamment mouillé les broches pour rester accroché sur les broches et se solidifiant rapidement sous la forme de billes, dès la séparation du circuit intégré de la plaque à alvéoles, l'alliage n'ayant pas le temps de s'étaler le long des broches.- The cell plate (68) is heated until the solder melts in the cells (70) producing the gravity separation of the integrated circuit (60) from the cell plate and the formation of the solder balls (72) at the ends of the pins, the alloy having sufficiently wetted the pins to remain attached to the pins and solidifies rapidly in the form of balls, as soon as the integrated circuit is separated from the cell plate, the alloy not having time to spread out along the pins.
2. Procédé de fabrication d'un circuit intégré de type montable en surface selon la revendication 1, caractérisé en ce que les extrémités des broches (64) sont insérées dans la plaque à alvéoles (68) jusqu'au fond des alvéoles (70).2. A method of manufacturing an integrated circuit of the surface mountable type according to claim 1, characterized in that the ends of the pins (64) are inserted in the cell plate (68) to the bottom of the cells (70).
3. Procédé de fabrication d'un circuit intégré de type montable en surface selon l'une des revendications 1 ou 2, caractérisé en ce que la plaque (68) à alvéoles est réalisée, soit en graphite soit en titane, soit dans un autre type de matériau adapté à la refusion.3. A method of manufacturing an integrated circuit of the surface mountable type according to one of claims 1 or 2, characterized in that the plate (68) with cells is made either of graphite or of titanium, or in another type of material suitable for reflow.
4. Procédé de fabrication d'un circuit intégré de type montable en surface, comprenant d'abord la fabrication d'un boîtier ayant une face arrière4. A method of manufacturing an integrated circuit of the surface mountable type, first comprising the manufacture of a housing having a rear face.
(62) et un réseau de broches de connexion, le réseau s'étendant sous cette face arrière perpendiculairement à celle-ci, et ensuite la formation à l'extrémité de chaque broche d'une bille (44, 72) d'alliage à bas point de fusion entourant cette extrémité et soudée à celle-ci, caractérisé en ce que, pour former la bille à l'extrémité de chaque broche :(62) and a network of connection pins, the network extending under this rear face perpendicular thereto, and then the formation at the end of each pin of a ball (44, 72) of alloy with low melting point surrounding this end and welded to it, characterized in that, to form the ball at the end of each pin:
- on place des billes d'alliage calibrées dans les alvéoles une plaque à alvéoles, dont les alvéoles (70) se trouvent réparties avec la même distribution que les broches (64) du boîtier du circuit intégré (60) ;- Placement of calibrated alloy balls is placed in the cells, a cell plate, the cells (70) of which are distributed with the same distribution as the pins (64) of the integrated circuit case (60);
- on fait fondre les billes ; - on insère les broches (64) du réseau de broches du circuit intégré (60) dans les alvéoles (70) comportant l'alliage fondu, le circuit intégré étant au-dessus de la plaque à alvéoles ;- the balls are melted; - The pins (64) of the network of pins of the integrated circuit (60) are inserted into the cells (70) comprising the molten alloy, the integrated circuit being above the cell plate;
- on refroidit très rapidement la plaque à alvéoles afin de ne pas laisser le temps à l'alliage liquide de remonter le long des connexions ; - on retourne alors le circuit intégré et la plaque d'alvéoles solidaire du circuit par l'alliage solidifié dans les alvéoles de façon à mettre la plaque à alvéoles au-dessus du circuit intégré, le circuit intégré étant suspendu à la plaque à alvéoles par ses broches prises dans l'alliage solidifié dans les alvéoles ; - on chauffe la plaque à alvéoles jusqu'à la fusion de la soudure dans les alvéoles produisant la séparation par gravité du circuit intégré de la plaque à alvéoles et la formation des billes (72) de soudure aux extrémités des broches, l'alliage ayant suffisamment mouillé les broches pour rester accroché sur les broches et se solidifiant rapidement sous la forme de billes, dès la séparation du circuit intégré de la plaque à alvéoles, l'alliage n'ayant pas le temps de s'étaler sur les broches.- the cell plate is cooled very quickly so as not to allow time for the liquid alloy to rise along the connections; - The integrated circuit and the cell plate secured to the circuit are then turned over by the alloy solidified in the cells so as to place the cell plate above the integrated circuit, the integrated circuit being suspended from the cell plate by its pins taken from the alloy solidified in the cells; - The cell plate is heated until the solder melts in the cells, producing the gravity separation of the integrated circuit from the cell plate and the formation of solder balls (72) at the ends of the pins, the alloy having sufficiently wet the pins to remain attached to the pins and solidify quickly in the form of balls, as soon as the integrated circuit separates from the cell plate, the alloy does not have time to spread over the pins.
5. Procédé de fabrication d'un circuit intégré de type montable en surface selon l'une des revendications 1 à 4, caractérisé en ce que les broches sont de section sensiblement constante le long de la broche.5. A method of manufacturing an integrated circuit of surface mountable type according to one of claims 1 to 4, characterized in that the pins are of substantially constant section along the spindle.
6. Procédé de fabrication d'un circuit intégré de type montable en surface selon l'une des revendications 1 à 5, caractérisé en ce que les broches sont lisses.6. A method of manufacturing an integrated circuit of the surface mountable type according to one of claims 1 to 5, characterized in that the pins are smooth.
7. Circuit intégré de type montable en surface (40, 60) comportant un boîtier ayant une face arrière (62) et un réseau de broches de connexion (42, 64) s'étendant sous la face arrière perpendiculairement à celle-ci, caractérisé en ce que l'extrémité de chaque broche comporte une bille (44, 72) d'alliage à bas point de fusion soudée à l'extrémité de chaque broche en entourant cette extrémité.7. Integrated circuit of surface-mountable type (40, 60) comprising a housing having a rear face (62) and a network of connection pins (42, 64) extending under the rear face perpendicular thereto, characterized in that the end of each pin comprises a ball (44, 72) of low-melting alloy welded to the end of each pin surrounding this end.
8. Circuit intégré de type montable en surface, selon la revendication 7, caractérisé en ce que la longueur d'extrémité de broche Le entourée par la bille (44, 72) est sensiblement égale au diamètre D de la bille.8. Integrated circuit of surface mountable type, according to claim 7, characterized in that the spindle end length Le surrounded by the ball (44, 72) is substantially equal to the diameter D of the ball.
9. Circuit intégré de type montable en surface, selon l'une des revendications 7 ou 8, caractérisé en ce que la longueur d'extrémité de broche Le entourée par la bille (44) est égale à la longueur de broche Lb dépassant de la face arrière (62) du boîtier.9. Integrated circuit of surface mountable type, according to one of claims 7 or 8, characterized in that the spindle end length Le surrounded by the ball (44) is equal to the spindle length Lb protruding from the rear face (62) of the housing.
10. Circuit intégré de type montable en surface, selon l'une des revendications 7 ou 8, caractérisé en ce que la longueur de broche dépassant de la face arrière du boîtier est supérieure au diamètre de la bille.10. Integrated circuit of surface-mountable type, according to one of claims 7 or 8, characterized in that the pin length protruding from the rear face of the housing is greater than the diameter of the ball.
11. Circuit intégré de type montable en surface, selon la revendication 7, caractérisé en ce que la longueur d'extrémité de broche Le entourée par la bille est inférieure au diamètre de la bille. 11. Integrated circuit of surface mount type, according to claim 7, characterized in that the spindle end length Le surrounded by the ball is less than the diameter of the ball.
12. Circuit intégré de type montable en surface, selon l'une des revendications 7 à 11, caractérisé en ce que la bille (44, 72) est un alliage en plomb/étain.12. Integrated circuit of surface mount type, according to one of claims 7 to 11, characterized in that the ball (44, 72) is a lead / tin alloy.
13. Circuit intégré de type montable en surface, selon la revendication 12, caractérisé en ce que l'alliage utilisé est un alliage couramment utilisé sur les cartes de circuit imprimé, tel qu'un alliage comportant 63% de plomb et 37% d'étain.13. Integrated circuit of surface mountable type, according to claim 12, characterized in that the alloy used is an alloy commonly used on printed circuit boards, such as an alloy comprising 63% lead and 37% tin.
14. Circuit intégré de type montable en surface, selon l'une des revendications 7 à 13, caractérisé en ce que le boîtier est un boîtier en céramique.14. Integrated circuit of surface mountable type, according to one of claims 7 to 13, characterized in that the housing is a ceramic housing.
15. Circuit intégré de type montable en surface, selon l'une des revendications 7 à 13, caractérisé en ce que le boîtier est un boîtier en matière plastique.15. Integrated circuit of surface mountable type according to one of claims 7 to 13, characterized in that the housing is a plastic housing.
16. Circuit intégré de type montable en surface, selon l'une des revendications 7 à 15, caractérisé en ce que les broches sont de section sensiblement constante le long de la broche.16. Integrated circuit of surface mount type, according to one of claims 7 to 15, characterized in that the pins are of substantially constant section along the spindle.
17. Circuit intégré de type montable en surface, selon l'une des revendications 7 à 16, caractérisé en ce que les broches sont lisses. 17. Integrated circuit of surface mount type, according to one of claims 7 to 16, characterized in that the pins are smooth.
EP00953253A 2000-07-18 2000-07-18 Method for making an integrated circuit capable of being surface-mounted and resulting circuit Withdrawn EP1314196A1 (en)

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PCT/FR2000/002063 WO2002007208A1 (en) 2000-07-18 2000-07-18 Method for making an integrated circuit capable of being surface-mounted and resulting circuit

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JP (1) JP2004504722A (en)
KR (1) KR20030059078A (en)
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KR20030059078A (en) * 2000-07-18 2003-07-07 아트멜 그르노블 에스아 Method for making an integrated circuit capable of being surface-mounted and resulting circuit
JP4744689B2 (en) * 2000-12-11 2011-08-10 パナソニック株式会社 Viscous fluid transfer device and electronic component mounting device

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AU2000265772A1 (en) 2002-01-30
IL154002A0 (en) 2003-07-31
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JP2004504722A (en) 2004-02-12
KR20030059078A (en) 2003-07-07
WO2002007208A1 (en) 2002-01-24

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