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WO1991006389A1 - Method and device for laser brazing - Google Patents

Method and device for laser brazing Download PDF

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Publication number
WO1991006389A1
WO1991006389A1 PCT/FR1990/000731 FR9000731W WO9106389A1 WO 1991006389 A1 WO1991006389 A1 WO 1991006389A1 FR 9000731 W FR9000731 W FR 9000731W WO 9106389 A1 WO9106389 A1 WO 9106389A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser
substrate
temperature
region
elements
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.)
Ceased
Application number
PCT/FR1990/000731
Other languages
French (fr)
Inventor
Patrice Cottin
Patrick Guivy
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.)
Quantel SA
Original Assignee
Quantel 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 Quantel SA filed Critical Quantel SA
Publication of WO1991006389A1 publication Critical patent/WO1991006389A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B23K26/034—Observing the temperature of the workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/005—Soldering by means of radiant energy
    • B23K1/0056—Soldering by means of radiant energy soldering by means of beams, e.g. lasers, E.B.
    • 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
    • H05K3/341—Surface mounted components
    • H05K3/3421—Leaded components
    • 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
    • H05K3/3494—Heating methods for reflowing of solder

Definitions

  • the present invention relates to a process for the brazing by laser beam of several approximately punctual metallic elements on a non-metallic substrate. It applies in particular to the manufacture of electronic circuit boards by soldering connection pins or the like (lugs, contacts, etc.) of various electronic components.
  • Laser soldering has significant advantages.
  • it is a contactless process in which the energy is deposited, with a high surface density, only in the zone where the solder is located, and can be controlled reliably and precisely.
  • the laser method therefore has the advantage of avoiding the heating of the components.
  • Degradations can indeed be encountered in conventional infra-red (IR) or vapor phase or wave soldering methods: the entire electronic card, including the sensitive components, is then subjected to temperatures of 200 ° C for several seconds or minutes.
  • IR infra-red
  • vapor phase or wave soldering methods the entire electronic card, including the sensitive components, is then subjected to temperatures of 200 ° C for several seconds or minutes.
  • a major drawback is that this point-by-point technique is relatively slow. Furthermore, in this point-by-point technique, the amount of laser energy absorbed by each soldering point as well as the surface illuminated by the laser are sensitive parameters: if they are poorly controlled, the temperature development of the solder is poorly controlled, resulting in defects quality: local burning of the substrate, pollution by dissemination of the soldering cream. These defects occur in particular when using an Nd-YAG laser at 1.06 / Am, which is often preferred to the CO laser (at 10.6 / * ⁇ * * - m) in the point-to-point soldering, because better absorption by the metallic materials involved in the soldering of the wavelength 1.06. m.
  • the object of the invention is to provide a technique allowing rapid and reliable soldering of series of connection pins or the like, with various types of laser, including CO lasers.
  • the subject of the invention is a method of the aforementioned type, characterized in that a region of the substrate which is entirely located in the immediate vicinity of all of said elements is heated overall by means of the laser, to a predetermined temperature at least equal to the fu ⁇ sion temperature of the soldering products and lower than the degradation temperature of the substrate.
  • the temperatures are about 220 ° C for melting of an alloy sour kind SnPb bra ⁇ and 300 ° C for temperature dé ⁇ gradation of an epoxy type substrate.
  • This process achieves two conditions which are not fulfilled at the same time by the other conventional or laser soldering processes: on the one hand, a series of soldering points are produced simultaneously, in a very short time, and on the other hand, the heat affected zone is limited to the useful zone without risk of damaging the substrate or the components to be brazed.
  • the heating is carried out by scanning said region with the laser beam, so that the whole of the region swept by the beam has a substantially uniform temperature.
  • This scanning corresponds to a periodic movement of the impact of the laser beam on the substrate in a region entirely located in the immediate vicinity of the elements to be brazed. This movement is fast enough for the heating of the substrate to be substantially homogeneous in the scanned area, the scanning period being short compared with the thermal constants of the substrate.
  • the temperature of said region is measured by means of a pyrometer which measures the intensity of a radiation characteristic of the substrate, in particular by reflex aiming of said region, this characteristic radiation corresponding to a length of wave different from that emitted by the laser.
  • FIG. 1 schematically shows in perspective an apparatus according to the invention
  • Fig. 2 is a plan view of an electronic circuit board produced in accordance with the invention, by means of the apparatus of FIG. 1.
  • a first dichroic plate 11 allowing the superposition of the two laser beams, an optical focusing system 12, and a second dichroic plate 13; an infrared pyrometer 14 to which the mirrors 3 and 4 and the blade 13 return a ray 15 characteristic of the substrate 2, emitted by the latter, and the intensity of which is representative of the temperature of this substrate.
  • an organic material substrate such as a substrate epoxy
  • a pyrometer which is suitable for this temperature measurement is the MODLINE type pyrometer , series. 3400, from IRCON; an electronic computer 17, such as a microprocessor, provided with software for managing and controlling the laser emission as well as the oscillating movements of the mirrors and those of the support 1, as described below , via interfaces 18 (for the laser) and 19 (for the motors 7 and 8).
  • the interface 18 also serves as an interface between the pyrometer 14 and the laser 9, for modulating the power of the laser beam, as described below.
  • small passive elements 20 such as two-pole miniaturized resistors 20A; larger passive elements such as resistors 21 of elongated shape comprising two projecting end connection lugs 22, or a capacitor 23 with two connection lugs 24 in juxtaposed sail ⁇ lie; complex rectangular electronic boxes with two opposite sides (boxes 25, 26, 27) or on the four sides (box 28) a series of connection pins very close to each other.
  • the pins 29 practically do not project in plan view, while the pins 30 of the boxes 27 and 28 project clearly; a so-called card edge connector 31 having a plurality of connection tabs 32 projecting substantially along one edge of the substrate.
  • each pin or the like ends up on a pad of a circuit track defined on the substrate.
  • the pad can be pre-tinned (refusi ⁇ n technique) or coated with solder cream.
  • regions of the substrate having an appropriate shape, generally rectangular, and each of which is entirely located in the immediate vicinity of a series of connection pins to be fixed by soldering. These regions are of three types:
  • Regions 35 running along an edge of a component and into which a projecting pin or a series of juxtaposed projecting pins clearly penetrate (components 21-, 23, 27, 28 and 31).
  • the control software of the computer 17 is adapted so that the laser beam is directed successively on each of the regions 33 to 35 and, each time, sweeps the working region by virtue of the movement of a mirror or of the two mirrors, namely a sinusoidal or sawtooth movement, in the direction of the length the region, with a frequency of 50 Hz to 1 kHz, and possibly a slow movement perpendicular to the previous one.
  • the substrate emits radiation at 3.43 * m measured by the pyrometer, which "directly" sees the working region since it is arranged in reflex view.
  • This pyrometer has a set temperature value at least equal to the melting temperature of the soldering products and lower than the degradation temperature of the substrate, and it emits to the laser 9, via the interface 18, a deviation signal which changes the power of the laser in the direction tending to cancel this deviation. The laser power is thus controlled at the set temperature.
  • the regions 33 to 35 are defined so that the exposed substrate surface is sufficiently large relative to the metallic surface, and / or the printed circuit cir ⁇ metal tracks are covered, in their non-soldered parts, with a savings varnish absorbing the laser radiation.
  • the substrate is heated in the immediate vicinity of these metal parts, and it is the substrate which heats by conduction of the brazing pads to the temperature of -fusion of the soldering products.
  • the radiation at 10.6 / Am is well absorbed by the substrates used to constitute the electronic cards (plastic type Epoxy or ceramic type Al 0). This property of high absorption of the substrate at the wavelength of the lasers, which is considered to be a drawback in the conventional point-by-point technique, is thus taken advantage of in the context of the present invention.
  • the CO laser can be replaced by a CO or Nd-YAG laser, the radiation of which is also strongly absorbed by the organic substrates.
  • the laser used is preferably a continuously operating laser, as in the example described above. However, a pulsed laser could also be used.

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Plasma & Fusion (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)

Abstract

A series of connection pins on a non metallic substrate (2) is brazed simultaneously by sweeping a laser beam over a region of the substrate next to the set of pins. Application is found in the manufacture of electronic circuit boards.

Description

-"Procédé et appareil de brasage au laser". - "Laser brazing process and apparatus".

La présente invention est relative à un pro¬ cédé pour le brasage par faisceau laser de plusieurs éléments métalliques à peu près ponctuels sur un substrat non métallique. Elle s'applique en particulier à la fabrication des cartes de circuits électroniques par brasage des broches de connexion ou analogues (pattes, contacts, ... ) de divers composants électroniques .The present invention relates to a process for the brazing by laser beam of several approximately punctual metallic elements on a non-metallic substrate. It applies in particular to the manufacture of electronic circuit boards by soldering connection pins or the like (lugs, contacts, etc.) of various electronic components.

Le brasage au laser présente des avantages importants. En particulier, il s'agit d'un procédé sans contact dans lequel l'énergie est déposée, avec une forte densité surfacique, uniquement dans la zone où se situe la brasure, et peut être commandée de façon fiable et précise.Laser soldering has significant advantages. In particular, it is a contactless process in which the energy is deposited, with a high surface density, only in the zone where the solder is located, and can be controlled reliably and precisely.

Pour la fabrication de cartes électroniques notamment, le procédé au laser a donc l'avantage d'é¬ viter le chauffage des composants. Des dégradations peuvent être en effet rencontrées dans les procédés conventionnels de brasage par four infra-rouge (I.R.) ou en phase vapeur ou à la vague : l'ensemble de la carte électronique, y compris les composants sensi¬ bles, sont alors soumis à des températures voisines de 200*C pendant plusieurs secondes ou minutes.For the manufacture of electronic cards in particular, the laser method therefore has the advantage of avoiding the heating of the components. Degradations can indeed be encountered in conventional infra-red (IR) or vapor phase or wave soldering methods: the entire electronic card, including the sensitive components, is then subjected to temperatures of 200 ° C for several seconds or minutes.

Cependant, lorsqu'il s'agit de braser au la¬ ser une série de broches de connexion de composants électroniques sur une carte de circuit imprimé, la technique de mise en oeuvre classique, qui consiste à effectuer un brasage séquentiel point par point en envoyant successivement le faisceau laser focalisé sur chaque contact à braser, présente certains inconvé¬ nients .However, when it is a question of soldering a series of pins for connecting electronic components to a printed circuit board, the conventional implementation technique which consists in carrying out sequential point-to-point soldering by sending successively the laser beam focused on each contact to be soldered has certain drawbacks.

Un inconvénient majeur est que cette techni-que point par point est relativement lente. Par ailleurs, dans cette technique point par point, la quantité d'énergie laser absorbée par chaque point de brasure ainsi que la surface éclairée par le laser sont des paramètres sensibles : s'ils sont mal maîtrisés, l'évolution de température de la brasure est mal contrôlée, d'où il résulte des défauts de qualité : brûlure locale du substrat, pollution par dissémination de la crème à braser. Ces défauts se produisent notamment lorsqu'on utilise un laser Nd-YAG à 1.06/A-m, qui est souvent préféré au laser à CO (à 10,6 /*<**-- m) dans la brasure point par point, du fait d'une meilleure absorption par les matériaux métalliques intervenant dans la brasure de la longueur d ' onde 1 , 06 . m.A major drawback is that this point-by-point technique is relatively slow. Furthermore, in this point-by-point technique, the amount of laser energy absorbed by each soldering point as well as the surface illuminated by the laser are sensitive parameters: if they are poorly controlled, the temperature development of the solder is poorly controlled, resulting in defects quality: local burning of the substrate, pollution by dissemination of the soldering cream. These defects occur in particular when using an Nd-YAG laser at 1.06 / Am, which is often preferred to the CO laser (at 10.6 / * <* * - m) in the point-to-point soldering, because better absorption by the metallic materials involved in the soldering of the wavelength 1.06. m.

L'invention a pour but de fournir une tech¬ nique permettant un brasage fiable et rapide de séries de broches de connexion ou analogues, avec divers ty¬ pes de laser dont les lasers CO .The object of the invention is to provide a technique allowing rapid and reliable soldering of series of connection pins or the like, with various types of laser, including CO lasers.

A cet effet, l'invention a pour objet un procédé du type précité, caractérisé en ce qu'on chauffe globalement au moyen du laser une région du substrat entièrement située à proximité immédiate de l'ensemble desdits éléments, jusqu'à une température prédéterminée au moins égale à la température de fu¬ sion des produits de brasage et inférieure à la tem¬ pérature de dégradation du substrat.To this end, the subject of the invention is a method of the aforementioned type, characterized in that a region of the substrate which is entirely located in the immediate vicinity of all of said elements is heated overall by means of the laser, to a predetermined temperature at least equal to the fu¬ sion temperature of the soldering products and lower than the degradation temperature of the substrate.

A titre indicatif, les températures sont de l'ordre de 220*C pour la fusion d'un alliage de bra¬ sure type SnPb et de 300*C pour la température de dé¬ gradation d'un substrat de type Epoxy. On parvient par ce procédé à satisfaire deux conditions qui ne sont pas remplies en même temps par les autres procé¬ dés de brasage conventionnels ou par laser : d'une part, une série de points de brasure est réalisée simultanément, en un temps très bref, et d'autre part, la zone thermiquement affectée est limitée à la zone utile sans risque d'endommager le substrat ou les composants à braser.As an indication, the temperatures are about 220 ° C for melting of an alloy sour kind SnPb bra¬ and 300 ° C for temperature dé¬ gradation of an epoxy type substrate. This process achieves two conditions which are not fulfilled at the same time by the other conventional or laser soldering processes: on the one hand, a series of soldering points are produced simultaneously, in a very short time, and on the other hand, the heat affected zone is limited to the useful zone without risk of damaging the substrate or the components to be brazed.

Dans un mode de mise en oeuvre avantageux, on effectue le chauffage en balayant ladite région avec le faisceau laser, de telle manière que l'en¬ semble de la région balayée par le faisceau ait une température sensiblement homogène.In an advantageous embodiment, the heating is carried out by scanning said region with the laser beam, so that the whole of the region swept by the beam has a substantially uniform temperature.

Ce balayage correspond à un mouvement pé¬ riodique de l'impact du faisceau laser sur le substrat dans une région entièrement située à proximité immé¬ diate des éléments â braser. Ce mouvement est suffi¬ samment rapide pour que le chauffage du substrat soit sensiblement homogène dans la zone balayée, la période de balayage étant courte en regard des constantes thermiques du substrat.This scanning corresponds to a periodic movement of the impact of the laser beam on the substrate in a region entirely located in the immediate vicinity of the elements to be brazed. This movement is fast enough for the heating of the substrate to be substantially homogeneous in the scanned area, the scanning period being short compared with the thermal constants of the substrate.

De préférence, on mesure la température de ladite région au moyen d'un pyromètre qui mesure l'intensité d'un rayonnement caractéristique du subs¬ trat, notamment par visée reflex de ladite région, ce rayonnement caractéristique correspondant à une lon¬ gueur d'onde différente de celle émise par le laser.Preferably, the temperature of said region is measured by means of a pyrometer which measures the intensity of a radiation characteristic of the substrate, in particular by reflex aiming of said region, this characteristic radiation corresponding to a length of wave different from that emitted by the laser.

L'invention a également pour objet un appa¬ reil de brasage au laser destiné à la mise en oeuvre d'un tel procédé. Cet appareil est caractérisé en ce qu'il comprend : un support pour le substrat ; un laser ; des moyens pour défléchir le faisceau du laser ; et des moyens de commande des moyens de dé- flection assurant un balayage par le faisceau de régions localisées du substrat. Un exemple de mise en oeuvre de l'invention va maintenant être décrit en regard des dessins anne¬ xés, sur lesquels : la Fig . 1 représente schématiquement en perspective un appareil conforme à l'invention ; la Fig. 2 est une vue en plan d'une carte de circuits électroniques réalisée conformément à l'invention, au moyen de l'appareil de la Fig. 1.The invention also relates to an apparatus for laser soldering intended for the implementation of such a method. This device is characterized in that it comprises: a support for the substrate; a laser; means for deflecting the laser beam; and means for controlling the deflection means ensuring scanning by the beam of localized regions of the substrate. An example of implementation of the invention will now be described with reference to the appended drawings, in which: FIG. 1 schematically shows in perspective an apparatus according to the invention; Fig. 2 is a plan view of an electronic circuit board produced in accordance with the invention, by means of the apparatus of FIG. 1.

L'appareil représenté à la Fig. 1 comprend : un support horizontal 1 , muni de moyens (non représentés) de déplacement suivant deux direc¬ tions horizontales orthogonales X, Y, sur lequel peut se fixer une carte de circuits imprimés ou substrat 2; deux miroirs 3, 4 montés oscillants res¬ pectivement autour d'un axe horizontal 5 perpendicu¬ laire à la direction X et autour d'un axe vertical 6, et munis de moteurs d ' entraînement respectifs 7, 8 ; un laser CO 9 (longueur d'onde K = 10,6 *. m) à fonctionnement continu et à puis¬ sance réglable par exemple de 3 W à 50 W, associé à un laser He-Ne 10 émettant un faisceau de lumière visible qui se superpose au faisceau principal issu du laser 9. La sortie du laser 9 est orientée vers le centre du miroir 4 le plus proche. Entre cette sortie et le miroir 4 sont prévus successivement une première lame dichroïque 11 permettant la superposition des deux faisceaux laser, un système optique de focalisation 12, et une seconde lame dichroïque 13 ; un pyromètre infra-rouge 14 vers lequel les miroirs 3 et 4 et la lame 13 renvoient un rayonne¬ ment 15 caractéristique du substrat 2, émis par celui- ci, et dont l'intensité est représentative de la température de ce substrat. En particulier, pour un substrat en matière organique tel qu'un substrat époxy, on peut généralement utiliser un rayonnement de longueur d'onde 3,43 m, correspondant à la présence de liaisons carbone-hydrogène. Ce rayonnement, séparé par la lame 13 de la lumière laser diffusée par la ré¬ gion où s'effectue le brasage, est focalisé sur le pyromètre par un système optique 16. Un pyromètre qui convient pour cette mesure de température est le pyromètre type MODLINE, série. 3400, de la Société IRCON ; un calculateur électronique 17, tel qu'un microprocesseur, pourvu d'un logiciel de gestion et de commande de l'émission laser ainsi que des mouve¬ ments d'oscillation des miroirs et de ceux du support 1, de la manière décrite plus loin, par l'intermédi¬ aire d'interfaces 18 (pour le laser) et 19 (pour les moteurs 7 et 8). L'interface 18 sert également d'interface en-tre le pyromètre 14 et le laser 9, pour la modulation de la puissance du faisceau laser, comme décrit ci-dessous.The apparatus shown in FIG. 1 comprises: a horizontal support 1, provided with means (not shown) for displacement in two orthogonal horizontal directions X, Y, on which a printed circuit board or substrate 2 can be fixed; two mirrors 3, 4 mounted oscillating respectively around a horizontal axis 5 perpendicular to the direction X and around a vertical axis 6, and provided with respective drive motors 7, 8; a CO 9 laser (wavelength K = 10.6 * . m) with continuous operation and adjustable power, for example from 3 W to 50 W, associated with a He-Ne 10 laser emitting a visible light beam which is superimposed on the main beam from the laser 9. The output of the laser 9 is oriented towards the center of the nearest mirror 4. Between this outlet and the mirror 4 are provided successively a first dichroic plate 11 allowing the superposition of the two laser beams, an optical focusing system 12, and a second dichroic plate 13; an infrared pyrometer 14 to which the mirrors 3 and 4 and the blade 13 return a ray 15 characteristic of the substrate 2, emitted by the latter, and the intensity of which is representative of the temperature of this substrate. In particular, for an organic material substrate such as a substrate epoxy, it is generally possible to use radiation of wavelength 3.43 m, corresponding to the presence of carbon-hydrogen bonds. This radiation, separated by the blade 13 from the laser light scattered by the region where brazing takes place, is focused on the pyrometer by an optical system 16. A pyrometer which is suitable for this temperature measurement is the MODLINE type pyrometer , series. 3400, from IRCON; an electronic computer 17, such as a microprocessor, provided with software for managing and controlling the laser emission as well as the oscillating movements of the mirrors and those of the support 1, as described below , via interfaces 18 (for the laser) and 19 (for the motors 7 and 8). The interface 18 also serves as an interface between the pyrometer 14 and the laser 9, for modulating the power of the laser beam, as described below.

Avec l'appareil de la Fig. 1, on réalise une carte de circuits électroniques du type représenté à la Fig. 2, où seules certaines pistes de circuits im¬ primés portées par le substrat 2 ont été indiquées dans un but de clarté. Sur le substrat doivent être fixés par brasage : de petits éléments passifs 20 tels que des résistances miniaturisées à deux pôles 20A ; des éléments passifs plus grands tels que des résistances 21 de forme allongée comportant deux pattes de connexion d'extrémité 22 en saillie, ou un condensateur 23 à deux pattes de connexion 24 en sail¬ lie juxtaposées ; des boîtiers électroniques complexes de forme rectangulaire comportant sur deux côtés opposés (boîtiers 25, 26, 27) ou sur les quatre côtés (boîtier 28) une série de broches de connexion très rapprochées les unes des autres. Pour les boîtiers 25 et 26, les broches 29 ne font pratiquement pas saillie en vue en plan, alors que les broches 30 des boîtiers 27 et 28 font nettement saillie ; un connecteur marginal dit de bord de carte 31 présentant plusieurs pattes de connexion 32 en saillie importante le long d'un bord du substrat.With the apparatus of FIG. 1, an electronic circuit board of the type shown in FIG. 2, where only certain tracks of im¬ primed circuits carried by the substrate 2 have been indicated for the sake of clarity. On the substrate must be fixed by brazing: small passive elements 20 such as two-pole miniaturized resistors 20A; larger passive elements such as resistors 21 of elongated shape comprising two projecting end connection lugs 22, or a capacitor 23 with two connection lugs 24 in juxtaposed sail¬ lie; complex rectangular electronic boxes with two opposite sides (boxes 25, 26, 27) or on the four sides (box 28) a series of connection pins very close to each other. For the boxes 25 and 26, the pins 29 practically do not project in plan view, while the pins 30 of the boxes 27 and 28 project clearly; a so-called card edge connector 31 having a plurality of connection tabs 32 projecting substantially along one edge of the substrate.

De façon classique, chaque broche ou analogue aboutit sur un plot d'une piste de circuit définie sur le substrat. Le plot peut être préétamé (technique de refusiαn) ou revêtu de crème à braser.Conventionally, each pin or the like ends up on a pad of a circuit track defined on the substrate. The pad can be pre-tinned (refusiαn technique) or coated with solder cream.

Pour réaliser une telle carte, on commence par définir un certain nombre de régions du substrat ayant une forme appropriée, en général rectangulaire, et dont chacune est entièrement située au voisinage immédiat d'une série de broches de connexion à fixer par brasage. Ces régions sont de trois types :To make such a card, one begins by defining a certain number of regions of the substrate having an appropriate shape, generally rectangular, and each of which is entirely located in the immediate vicinity of a series of connection pins to be fixed by soldering. These regions are of three types:

( 1 ) Des régions 33 recouvrant complètement un ou plusieurs composants, lorsque ces derniers sont très petits et peuvent être chauffés sans dommage. Dans l'exemple représenté, il s'agit de régions recou¬ vrant une ou plusieurs résistances 20.(1) Regions 33 completely covering one or more components, when the latter are very small and can be heated without damage. In the example shown, these are regions covering one or more resistors 20.

(2) Des régions 34 immédiatement adjacentes à un bord d'un composant muni de broches 29 qui, en plan, ne font pratiquement pas saillie, comme c'est le cas pour les boîtiers 25 et 26, et(2) Regions 34 immediately adjacent to an edge of a component provided with pins 29 which, in plan, practically do not protrude, as is the case for housings 25 and 26, and

(3) Des régions 35 longeant un bord d'un composant et dans lesquelles pénètrent nettement une broche en saillie ou une série de broches juxtaposées en saillie (composants 21-, 23, 27, 28 et 31).(3) Regions 35 running along an edge of a component and into which a projecting pin or a series of juxtaposed projecting pins clearly penetrate (components 21-, 23, 27, 28 and 31).

Le logiciel de commande du calculateur 17 est adapté pour que le faisceau laser soit dirigé successivement sur chacune des régions 33 à 35 et, à chaque fois, balaye la région de travail grâce au mouvement d'un miroir ou des deux miroirs, à savoir un mouvement sinusoïdal ou en dents de scie rapide, dans le sens de la longueur de la région, avec une fréquence de 50 Hz à 1 kHz, et éventuellement un mouvement lent perpendiculaire au précédent.The control software of the computer 17 is adapted so that the laser beam is directed successively on each of the regions 33 to 35 and, each time, sweeps the working region by virtue of the movement of a mirror or of the two mirrors, namely a sinusoidal or sawtooth movement, in the direction of the length the region, with a frequency of 50 Hz to 1 kHz, and possibly a slow movement perpendicular to the previous one.

Pendant ce balayage, le substrat émet un rayonnement à 3,43 *m mesuré par le pyromètre, lequel "voit" directement la région de travail puisqu'il est agencé en visée reflex. Ce pyromètre possède une va¬ leur de température de consigne au moins égale à la température de fusion des produits de brasage et infé¬ rieure à la température de dégradation du substrat, et il émet vers le laser 9, via l'interface 18, un signal d'écart qui modifie la puissance du laser dans le sens tendant à annuler cet écart. La puissance du laser est ainsi asservie à la température de consigne.During this scanning, the substrate emits radiation at 3.43 * m measured by the pyrometer, which "directly" sees the working region since it is arranged in reflex view. This pyrometer has a set temperature value at least equal to the melting temperature of the soldering products and lower than the degradation temperature of the substrate, and it emits to the laser 9, via the interface 18, a deviation signal which changes the power of the laser in the direction tending to cancel this deviation. The laser power is thus controlled at the set temperature.

Pour éviter toute perte de précision de cette régulation due à la visée de parties métalliques par le pyromètre, on définit les régions 33 à 35 de façon que la surface de substrat exposée soit suffi- Opsamment importante par rapport à la surface métalli¬ que, et/ou on recouvre les pistes métalliques de cir¬ cuit imprimé, dans leurs parties non brasées, d'un vernis épargne absorbant le rayonnement laser.To avoid any loss of precision of this regulation due to the aiming of metallic parts by the pyrometer, the regions 33 to 35 are defined so that the exposed substrate surface is sufficiently large relative to the metallic surface, and / or the printed circuit cir¬ metal tracks are covered, in their non-soldered parts, with a savings varnish absorbing the laser radiation.

De cette manière, alors que les parties mé¬ talliques à braser n'absorbent que faiblement le rayonnement à 10,6 *** m, on chauffe le substrat à proximité immédiate de ces parties métalliques, et c'est le substrat qui chauffe par conduction les plots de brasage à la température de -fusion des produits de brasage. En effet, le rayonnement à 10,6/Am est bien absorbé par les substrats utilisés pour constituer les cartes électroniques (matières plastiques type Epoxy ou céramiques du type Al 0 ). Cette propriété d'ab¬ sorption élevée du substrat à la longueur d'onde des lasers, qui est considérée comme un inconvénient dans la technique classique point par point, est ainsi mise à profit dans le cadre de la présente invention.In this way, while the metal parts to be brazed absorb the radiation only slightly at 10.6 ** * m, the substrate is heated in the immediate vicinity of these metal parts, and it is the substrate which heats by conduction of the brazing pads to the temperature of -fusion of the soldering products. Indeed, the radiation at 10.6 / Am is well absorbed by the substrates used to constitute the electronic cards (plastic type Epoxy or ceramic type Al 0). This property of high absorption of the substrate at the wavelength of the lasers, which is considered to be a drawback in the conventional point-by-point technique, is thus taken advantage of in the context of the present invention.

En variante, on peut remplacer le laser CO par un laser CO ou Nd-YAG, dont les rayonnements sont également absorbés fortement par les substrats orga¬ niques. Le laser utilisé est de préférence un laser à fonctionnement continu, comme dans l'exemple décrit ci-dessus. Un laser puisé pourrait toutefois être utilisé également. Alternatively, the CO laser can be replaced by a CO or Nd-YAG laser, the radiation of which is also strongly absorbed by the organic substrates. The laser used is preferably a continuously operating laser, as in the example described above. However, a pulsed laser could also be used.

Claims

REVENDICATIONS 1. Procédé pour le brasage au laser de plusieurs éléments métalliques à peu près ponctuels (20. 22. 29, 30, 32) sur un substrat (2) non métalli¬ ques caractérisé en ce qu'on chauffe globalement au moyen du laser (9) une région (33 à 35) du substrat entièrement située à proximité immédiate de l'ensemble desdits éléments, jusqu'à une température prédétermi¬ née au moins égale à la température de fusion des produits de brasage et inférieure à la température de dégradation du substrat.CLAIMS 1. Method for the laser brazing of several approximately punctual metallic elements (20, 22, 29, 30, 32) on a non-metallic substrate (2) characterized in that one heats globally by means of the laser (9) a region (33 to 35) of the substrate entirely located in the immediate vicinity of all of said elements, up to a predetermined temperature born at least equal to the melting temperature of the brazing products and lower than the temperature of degradation of the substrate. 2. Procédé suivant la revendication 1, ca¬ ractérisée en ce que ladite région (33 à 35) contient une partie au moins desdits éléments métalliques (20, 22, 29. " 32) .2. Method according to claim 1, ca¬ acterized in that said region (33 to 35) contains at least part of said metal elements (20, 22, 29. " 32). 3. Procédé suivant l'une des revendications 1 et 2, caractérisé en ce qu'on effectue le chauffage En balayant ladite région (33 à 35) avec le faisceau laser, de telle manière que l'ensemble de la région balayée par le faisceau ait une température sensible¬ ment homogène.3. Method according to one of claims 1 and 2, characterized in that the heating is carried out By scanning said region (33 to 35) with the laser beam, so that the entire region scanned by the beam has a substantially homogeneous temperature. 4. Procédé suivant l'une quelconque des re¬ vendications 1 à 3, caractérisé en ce qu'on mesure la température de ladite région (33 à 35), et on règle la puissance du laser (9) de façon à annuler l'écart entre la température mesurée et ladite température prédéterminée.4. Method according to any one of claims 1 to 3, characterized in that the temperature of said region is measured (33 to 35), and the power of the laser (9) is adjusted so as to cancel the deviation between the measured temperature and said predetermined temperature. 5. Procédé suivant la revendication 4, ca¬ ractérisé en ce qu'on mesure la température de ladite région (33 à 35) au moyen d'un pyromètre (14) qui me¬ sure l'intensité d'un rayonnement caractéristique du substrat (2), notamment par visée reflex de ladite région, ce rayonnement caractéristique correspondant à une longueur d'onde différente de celle émise par le laser.5. Method according to claim 4, ca¬ characterized in that the temperature of said region (33 to 35) is measured by means of a pyrometer (14) which measures the intensity of a radiation characteristic of the substrate (2), in particular by reflex sighting of said region, this characteristic radiation corresponding to a wavelength different from that emitted by the laser. 6. Procédé suivant la revendication 5, ca¬ ractérisé en ce que, dans ladite région (33 à 35). l'aire dans laquelle le substrat (2) est exposé est importante par rapport à l'aire occupée par lesdits éléments métalliques (20, 22, 29. 32).6. Method according to claim 5, ca¬ acterized in that in said region (33 to 35). the area in which the substrate (2) is exposed is large compared to the area occupied by said metallic elements (20, 22, 29. 32). 7. Appareil pour le brasage au laser de plusieurs éléments métalliques, à peu près ponctuels (20, 22, 29, 30, 32)) sur un substrat (2) non métallique, caractérisé en ce qu'il comprend : un support (1) pour le substrat (2) ; un laser (9) ; des moyens (3, 4) pour défléchir le faisceau du laser ; et des moyens (7, 8, 17) de commande des moyens de deflection (3. 4) assurant un balayage par le faisceau de régions localisées (33 à 35) du substrat (2) .7. Apparatus for laser soldering of several metallic elements, roughly punctual (20, 22, 29, 30, 32)) on a non-metallic substrate (2), characterized in that it comprises: a support (1 ) for the substrate (2); a laser (9); means (3, 4) for deflecting the laser beam; and means (7, 8, 17) for controlling the deflection means (3. 4) ensuring scanning by the beam of localized regions (33 to 35) of the substrate (2). 8. Appareil suivant la revendication 7, ca¬ ractérisé en ce qu'il comprend un pyromètre (14) adap¬ té pour mesure l'intensité de l'émission par le subs¬ trat (2) d'un rayonnement caractéristique de ce subs¬ trat, et pour commander la puissance du laser (9) de façon à annuler l'écart entre la température mesurée et une température prédéterminée au moins égale à la température de fusion des produits de brasage et infé¬ rieure à la température de dégradation du substrat.8. Apparatus according to claim 7, ca¬ characterized in that it comprises a pyrometer (14) adapted for measuring the intensity of the emission by the subs¬ trat (2) of radiation characteristic of this subs ¬ trat, and to control the power of the laser (9) so as to cancel the difference between the measured temperature and a predetermined temperature at least equal to the melting temperature of the soldering products and lower than the degradation temperature of the substrate. 9. Appareil suivant la revendication 8, ca¬ ractérisé en ce que les moyens de deflection compren¬ nent au moins un miroir (3, 4), et en ce que le pyro¬ mètre (14) est interposé sur le trajet lumineux réflé¬ chi par le miroir (3, 4) et par une lame dichroïque (13) interposée sur le trajet du faisceau incident, cette lame dichroïque isolant le pyromètre de la lu¬ mière du laser diffusée par les éléments à braser.9. Apparatus according to claim 8, ca¬ characterized in that the deflection means comprise at least one mirror (3, 4), and in that the pyro¬ meter (14) is interposed on the light path reflected chi by the mirror (3, 4) and by a dichroic blade (13) interposed on the path of the incident beam, this dichroic blade isolating the pyrometer from the laser light diffused by the elements to be brazed. 10. Appareil suivant l'une quelconque des revendications 7 à 9, caractérisé en ce que le laser (9) est un laser CO ou CO ou Nd-YAG, notamment à fonctionnement continu. 10. Apparatus according to any one of claims 7 to 9, characterized in that the laser (9) is a CO or CO or Nd-YAG laser, in particular with continuous operation.
PCT/FR1990/000731 1989-10-24 1990-10-12 Method and device for laser brazing Ceased WO1991006389A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR89/13937 1989-10-24
FR8913937A FR2653367A1 (en) 1989-10-24 1989-10-24 LASER BRAZING PROCESS AND APPARATUS.

Publications (1)

Publication Number Publication Date
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999026753A1 (en) * 1997-11-20 1999-06-03 Pac Tech - Packaging Technologies Gmbh Method and device for thermally bonding connecting surfaces of two substrates
EP1110654A1 (en) * 1999-10-21 2001-06-27 Leister Process Technologies Method and apparatus for selective heating of components
WO2018158077A1 (en) * 2017-02-28 2018-09-07 Pac Tech - Packaging Technologies Gmbh Method and laser assembly for melting a solder material deposit by means of laser energy

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10213577B3 (en) * 2002-03-26 2004-02-19 Siemens Ag Process for simultaneous laser beam soldering

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0223066A1 (en) * 1985-11-11 1987-05-27 Siemens Nixdorf Informationssysteme Aktiengesellschaft Device for soldering electronic components on a printed-circuit board
DE3701013A1 (en) * 1987-01-15 1988-07-28 Messerschmitt Boelkow Blohm METHOD FOR MICROLOETING

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0223066A1 (en) * 1985-11-11 1987-05-27 Siemens Nixdorf Informationssysteme Aktiengesellschaft Device for soldering electronic components on a printed-circuit board
DE3701013A1 (en) * 1987-01-15 1988-07-28 Messerschmitt Boelkow Blohm METHOD FOR MICROLOETING

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Design Engineering, juin 1987, (London, GB), "Sensor-based laser scanner links solder joint integrity to production line performance", pages 25-28 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999026753A1 (en) * 1997-11-20 1999-06-03 Pac Tech - Packaging Technologies Gmbh Method and device for thermally bonding connecting surfaces of two substrates
US6394158B1 (en) 1997-11-20 2002-05-28 Pac Tech Packaging Technologies Gmbh Method and device for thermally bonding connecting surfaces of two substrates
EP1283085A1 (en) * 1997-11-20 2003-02-12 Pac Tech - Packaging Technologies GmbH Method and apparatus for thermal assembling of connecting areas of two substrates
EP1110654A1 (en) * 1999-10-21 2001-06-27 Leister Process Technologies Method and apparatus for selective heating of components
WO2018158077A1 (en) * 2017-02-28 2018-09-07 Pac Tech - Packaging Technologies Gmbh Method and laser assembly for melting a solder material deposit by means of laser energy
CN109070267A (en) * 2017-02-28 2018-12-21 派克泰克封装技术有限公司 For the method and laser equipment by means of laser energy fusing solder deposits
JP2019517922A (en) * 2017-02-28 2019-06-27 パック テック−パッケージング テクノロジーズ ゲーエムベーハー Method and laser configuration for melting solder material deposits by laser energy
TWI702999B (en) * 2017-02-28 2020-09-01 德商派克科技-包裝科技有限公司 Method and laser arrangement for fusing a solder material deposit by means of laser energy
CN109070267B (en) * 2017-02-28 2022-04-29 派克泰克封装技术有限公司 Method and laser device for melting solder deposits by means of laser energy
US11554434B2 (en) 2017-02-28 2023-01-17 PAC Tech—Packaging Technologies GmbH Method and laser arrangement for fusing a solder material deposit by means of laser energy

Also Published As

Publication number Publication date
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FR2653367A1 (en) 1991-04-26

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