EP0903061A1 - Process for reflow soldering of circuit boards fitted with smd components - Google Patents

Process for reflow soldering of circuit boards fitted with smd components

Info

Publication number
EP0903061A1
EP0903061A1 EP97943748A EP97943748A EP0903061A1 EP 0903061 A1 EP0903061 A1 EP 0903061A1 EP 97943748 A EP97943748 A EP 97943748A EP 97943748 A EP97943748 A EP 97943748A EP 0903061 A1 EP0903061 A1 EP 0903061A1
Authority
EP
European Patent Office
Prior art keywords
circuit board
reflow soldering
components
smd components
printed circuit
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Withdrawn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
EP97943748A
Other languages
German (de)
French (fr)
Inventor
Andreas Neutel
Joachim Schmidt
Jens Sabotke
Frank-Dieter Hauschild
Ansgar Graen
Carola Baran
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP0903061A1 publication Critical patent/EP0903061A1/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Withdrawn legal-status Critical Current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
    • H05K3/303—Surface mounted components, e.g. affixing before soldering, aligning means, spacing means
    • H05K3/305—Affixing by adhesive
    • 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
    • H05K3/3415—Surface mounted components on both sides of the substrate or combined with lead-in-hole 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
    • H05K1/00—Printed circuits
    • H05K1/18—Printed circuits structurally associated with non-printed electric components
    • H05K1/181—Printed circuits structurally associated with non-printed electric components associated with surface mounted 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
    • H05K3/3457—Solder materials or compositions; Methods of application thereof
    • H05K3/3468—Applying molten solder
    • 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
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09009—Substrate related
    • H05K2201/09072—Hole or recess under component or special relationship between hole and component
    • 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
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
    • H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
    • H05K2201/10621—Components characterised by their electrical contacts
    • H05K2201/10628—Leaded surface mounted device
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/14—Related to the order of processing steps
    • H05K2203/1476—Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/15—Position of the PCB during processing
    • H05K2203/1572—Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
    • 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 is based on a method according to the type specified in the preamble of claim 1.
  • SMD Surface Mounted Device
  • a method is known from EP 0 419 065 A2 in which a printed circuit board is first printed on its first side in a solder paste printing station with soldering areas at the locations provided for the application of SMD components. Subsequently, the circuit board is provided in an adhesive station between the soldering points with an adhesive drop for fixing the SMD components and then fitted with SMD components in a pick and place device, which are placed on the soldering surfaces and the adhesive. Since the components have to be pressed into the adhesive, the exact placement of the components can be hindered by the adhesive.
  • the adhesive is cured and the circuit board is fed to a reflow soldering station, in which the solder applied to the first side is melted and the components are soldered to the circuit board.
  • the printed circuit boards are turned over with the second side facing upwards and then again printed with soldering areas and then fitted with SMD components.
  • the circuit board is again fed to a reflow soldering station.
  • both the solder on the second side and the solder on the lower first side are melted.
  • the adhesive between the SMD components located on the first side and the printed circuit board prevents the SMD components already soldered to the first side from being detached from the printed circuit board by their weight when the soldered connections are re-melted.
  • a disadvantage of the method known from EP 0 419 065 A2 is that the adhesive is applied to the printed circuit board before the first reflow soldering step, since then the molten solder paste can contract below the components fixed by the adhesive, or the components by the adhesive be pressed out of the molten solder paste. This effect, known as "settling", has the effect that there are no or only inadequate electrical connections between the SMD components and the soldered connection areas on the printed circuit board.
  • Another method known in the prior art therefore provides for the adhesive to be applied between the component and the printed circuit board only after the first reflow soldering of the SMD components.
  • the adhesive is applied in a bead-like manner in the region of the side edges of the components, so that it connects the SMD components at their edges to the printed circuit board surface.
  • Adhesive can get onto the soldering surfaces during application, which can contaminate and contaminate them. During the second reflow soldering step, the quality of the electrical connection between the SMD component and the printed circuit board is reduced by the contamination.
  • the method according to the invention for reflow soldering printed circuit boards equipped with SMD components with the characterizing feature of the main claim has the advantage that the adhesive is only applied after the first reflow soldering step and, at the same time, contamination of the soldering surfaces on the first side of the lead provided with the adhesive terplatten is avoided. This is easily achieved by injecting the adhesive after the first reflow soldering from the still freely accessible second side of the printed circuit board through openings provided in the narrow space between the component and the printed circuit board. This advantageously avoids both the settling of the SMD components and an impairment of the electrical conductivity of the solder joints between the component and the printed circuit board caused by the adhesive.
  • the method according to the invention can be carried out, for example, in an automatic production line in which the circuit boards on conveyor belts pass through the individual stations one after the other.
  • the printed circuit boards have a first and a second side opposite this, both of which are to be equipped with SMD components.
  • an opening is provided, which extends from the first side to the second side of the printed circuit board.
  • the opening can be designed, for example, as a bore with a diameter of approximately 1 mm.
  • the printed circuit board is then fed to an SMD placement device, which attaches SMD components to the soldering areas on the first side using a suction pipette.
  • the printed circuit board is fed to a reflow soldering station, in which the components applied on the first side are soldered to the connection areas.
  • the circuit board is then turned over and fed to an adhesive station.
  • a cannula which is inserted from the second side of the printed circuit board above into the openings now located above the components, is used to inject adhesive into the space between the first side of the printed circuit board and the connection side of the SMD components. In the process carried out in this way, the adhesive can be metered exactly so that it does not flow out of the space between the component and the printed circuit board.
  • the adhesive is cured behind the adhesive station in a hardening station.
  • adhesives can also be used that are cured in the reflow soldering station.
  • the Printed circuit boards are now again fed to a solder paste printing station and printed with solder paste on the connection surfaces of the upward-facing second printed circuit board side.
  • the circuit boards are then fitted with SMD components in a placement machine on the second side and again fed to a reflow soldering station. During the second reflow soldering step, the components applied to the second side are soldered to the circuit board.
  • solder of the components already soldered to the connection faces of the first side is melted again, the drops of adhesive between the component and the circuit board preventing the SMD components from detaching from the circuit board due to their weight.
  • the components are soldered to the connection areas on both sides of the printed circuit board.

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)
  • Combinations Of Printed Boards (AREA)

Abstract

This invention concerns a process for reflow soldering of circuit boards fitted SMD components in which SMD components are placed on soldering surfaces of the first side of a circuit board and soldered to the circuit board in a first reflow soldering step. Subsequently the circuit board is turned with the first side underneath and SMD components are placed on soldering surfaces of the upward-facing second side, which are soldered to the circuit board in a subsequent reflow soldering step. The SMD components on the first side of the circuit board are firmly cemented to the circuit board before the second reflow soldering step on the first side. It is proposed that after the first reflow soldering step a cement be injected from the second side of the circuit board through holes which pass through the circuit board and correspond to the components soldered to the first side of the board into the space between the components and circuit board.

Description

Verfahren zum Reflowlöten von mit SMP-Bauelementen bestückten LeiterplattenProcess for reflow soldering of printed circuit boards with SMP components
Stand der TechnikState of the art
Die Erfindung geht von einem Verfahren nach der im Oberbegriff des Anspruchs 1 angegebenen Gattung aus.The invention is based on a method according to the type specified in the preamble of claim 1.
Derartige Verfahren sind bereits seit längerem bekannt und werden in der Leiterplattenfertigung eingesetzt, um Leiterplatten beidseitig mit SMD-Bauelementen (SMD = Surface Moun- ted Device) im Reflowlötverfahren zu verlöten. So ist beispielsweise aus der EP 0 419 065 A2 ein Verfahren bekannt, bei dem eine Leiterplatte zunächst auf ihrer ersten Seite in einer Lötpastendruckstation an den zur Aufbringung von SMD- Bauelementen vorgesehenen Stellen mit Lötflächen bedruckt wird. Anschließend wird die Leiterplatte in einer Kleberstation zwischen den Lötstellen mit einem Klebertropfen zur Fi- xierung der SMD-Bauelemente versehen und danach in einem Bestücker mit SMD-Bauelementen bestückt, die auf die Lötflächen und den Kleber aufgesetzt werden. Da die Bauelemente in den Kleber eingedrückt werden müssen, kann das genaue Aufsetzen der Bauelemente durch den Kleber behindert werden. Nach dem Bestücken wird der Kleber ausgehärtet und die Leiterplatte einer Reflowlötstation zugeführt, in der das auf die erste Seite aufgebrachte Lot aufgeschmolzen wird und die Bauelemente mit der Leiterplatte verlötet werden. Nach dem ersten Reflowlötschritt werden die Leiterplatten mit der zweiten Seite nach oben gewendet und nun erneut mit Lötflächen bedruckt und anschließend mit SMD-Bauelementen bestückt. Nach der Bestückung der zweiten Seite wird die Lei- terplatte erneut einer Reflowlötstation zugeführt . Während des zweiten Reflowlötschrittes wird sowohl das Lot auf der zweiten Seite als auch das Lot auf der unten liegenden ersten Seite aufgeschmolzen. Dabei verhindert der Kleber zwischen den auf der ersten Seite befindlichen SMD-Bauelementen und der Leiterplatte, daß die bereits mit der ersten Seite verlöteten SMD-Bauelemente beim erneuten Aufschmelzen der Lötverbindungen durch ihre Gewichtskraft von der Leiterplatte abgelöst werden. Nachteilig bei dem aus der EP 0 419 065 A2 bekannten Verfahren ist, daß der Kleber vor dem ersten Reflowlötschritt auf die Leiterplatte aufgebracht wird, da sich dann die geschmolzene Lotpaste unterhalb der durch den Kleber fixierten Bauelemente zusammenziehen kann, bzw. die Bauelemente durch den Kleber aus der geschmolzenen Lotpaste herausgedrückt werden. Dieser als „Settling" bekannte Effekt bewirkt, daß keine oder nur unzureichende elektrische Verbindungen zwischen den SMD-Bauelementen und den beloteten Anschlußflächen auf der Leiterplatte entstehen.Such methods have long been known and are used in printed circuit board production in order to solder printed circuit boards on both sides with SMD components (SMD = Surface Mounted Device) using the reflow soldering method. For example, a method is known from EP 0 419 065 A2 in which a printed circuit board is first printed on its first side in a solder paste printing station with soldering areas at the locations provided for the application of SMD components. Subsequently, the circuit board is provided in an adhesive station between the soldering points with an adhesive drop for fixing the SMD components and then fitted with SMD components in a pick and place device, which are placed on the soldering surfaces and the adhesive. Since the components have to be pressed into the adhesive, the exact placement of the components can be hindered by the adhesive. After the assembly, the adhesive is cured and the circuit board is fed to a reflow soldering station, in which the solder applied to the first side is melted and the components are soldered to the circuit board. After this In the first reflow soldering step, the printed circuit boards are turned over with the second side facing upwards and then again printed with soldering areas and then fitted with SMD components. After equipping the second side, the circuit board is again fed to a reflow soldering station. During the second reflow soldering step, both the solder on the second side and the solder on the lower first side are melted. The adhesive between the SMD components located on the first side and the printed circuit board prevents the SMD components already soldered to the first side from being detached from the printed circuit board by their weight when the soldered connections are re-melted. A disadvantage of the method known from EP 0 419 065 A2 is that the adhesive is applied to the printed circuit board before the first reflow soldering step, since then the molten solder paste can contract below the components fixed by the adhesive, or the components by the adhesive be pressed out of the molten solder paste. This effect, known as "settling", has the effect that there are no or only inadequate electrical connections between the SMD components and the soldered connection areas on the printed circuit board.
Ein anderes im Stand der Technik bekanntes Verfahren sieht deshalb vor, den Kleber erst nach dem ersten Reflowlöten der SMD-Bauelemente zwischen Bauelement und Leiterplatte aufzutragen. Bei diesem Verfahren wird der Kleber im Bereich der Seitenränder der Bauelemente wulstartig aufgetragen, so daß er die SMD-Bauelemente an deren Rändern mit der Leiterplat- tenoberflache verbindet. Nachteilig hierbei ist, daß derAnother method known in the prior art therefore provides for the adhesive to be applied between the component and the printed circuit board only after the first reflow soldering of the SMD components. In this method, the adhesive is applied in a bead-like manner in the region of the side edges of the components, so that it connects the SMD components at their edges to the printed circuit board surface. The disadvantage here is that the
Kleber beim Auftragen auf die Lötflächen gelangen kann und diese dadurch verschmutzt und verunreinigt werden. Bei dem anschließend durchgeführten zweiten Reflowlötschritt wird die Qualität der elektrischen Verbindung zwischen SMD-Bau- element und Leiterplatte durch die Verunreinigung vermindert . Vorteile der ErfindungAdhesive can get onto the soldering surfaces during application, which can contaminate and contaminate them. During the second reflow soldering step, the quality of the electrical connection between the SMD component and the printed circuit board is reduced by the contamination. Advantages of the invention
Das erfindungsgemäße Verfahren zum Reflowlöten von mit SMD- Bauelementen bestückten Leiterplatten mit dem kennzeichnenden Merkmal des Hauptanspruchs hat demgegenüber den Vorteil, daß der Kleber erst nach dem ersten Reflowlötschritt aufgetragen wird und gleichzeitig eine Verschmutzung der Lötflächen auf der mit dem Kleber versehenen ersten Seite der Lei- terplatten vermieden wird. Dies wird auf einfache Weise dadurch erreicht, daß der Kleber nach dem ersten Reflowlöten von der noch frei zugänglichen zweiten Seite der Leiterplatte aus durch eine dafür vorgesehene Öffnungen in den schmalen Zwischenraum zwischen Bauelement und Leiterplatte einge- spritzt wird. Hierdurch wird vorteilhaft sowohl das Settling der SMD-Bauelemente als auch eine durch den Kleber verursachte Beeinträchtigung der elektrischen Leitfähigkeit der Lötstellen zwischen Bauelement und Leiterplatte vermieden. Für das erfindungsgemäße Verfahren ist keine wesentliche Ab- änderung der Fertigungsmaschinen und der Prozeßreihenfolge erforderlich, so daß hierfür keine zusätzlichen Kosten entstehen. Weiterhin ist vorteilhaft, daß die Bestückung der ersten Seite der Leiterplatte mit SMD-Bauelementen nicht durch den Kleber behindert wird und die SMD-Bauelemente pro- blemlos auf die Lötflächen aufgesetzt werden können.The method according to the invention for reflow soldering printed circuit boards equipped with SMD components with the characterizing feature of the main claim has the advantage that the adhesive is only applied after the first reflow soldering step and, at the same time, contamination of the soldering surfaces on the first side of the lead provided with the adhesive terplatten is avoided. This is easily achieved by injecting the adhesive after the first reflow soldering from the still freely accessible second side of the printed circuit board through openings provided in the narrow space between the component and the printed circuit board. This advantageously avoids both the settling of the SMD components and an impairment of the electrical conductivity of the solder joints between the component and the printed circuit board caused by the adhesive. For the method according to the invention, no substantial change in the production machines and the process sequence is necessary, so that there are no additional costs for this. It is also advantageous that the assembly of the first side of the circuit board with SMD components is not hindered by the adhesive and that the SMD components can be easily placed on the soldering surfaces.
Besonders vorteilhaft ist es, den Kleber nach dem Wenden der Leiterplatte mit einer in die Öffnung eingeführten Kanüle direkt in den Raum zwischen der Anschlußseite des SMD-Bau- elementes und der ersten Seite der Leiterplatte einzuspritzen, um den Kleber optimal zu dosieren.It is particularly advantageous to inject the adhesive directly into the space between the connection side of the SMD component and the first side of the circuit board with a cannula inserted into the opening in order to optimally dose the adhesive.
Beschreibung eines AusführungsbeispielsDescription of an embodiment
Das erfindungsgemäße Verfahren kann zum Beispiel in einer automatischen Fertigungslinie durchgeführt werden, in der die Leiterplatten auf Transportbändern nacheinander die einzelnen Stationen durchlaufen. Die Leiterplatten weisen eine erste und eine dieser gegenüberliegende zweite Seite auf, die beide mit SMD-Bauelementen bestückt werden sollen. An den für die Aufbringung von SMD-Bauelemente bestimmten Stellen der ersten Seite der Leiterplatte ist jeweils eine Öffnung vorgesehen, die sich ausgehend von der ersten Seite bis zur zweiten Seite der Leiterplatte erstreckt . Die Öffnung kann z.B. als Bohrung mit einem Durchmesser von etwa 1 mm ausgebildet sein. Das Verfahren beginnt damit, daß eine beidseitig mit Anschlußflächen für SMD-Bauelemente und mit den beschriebenen Öffnungen versehene Leiterplatte einer Lötpastendruckstation zugeführt wird, in der Lötpaste auf die Anschlußflächen der ersten Seite der Leiterplatte aufge- bracht wird. Anschließend wird die Leiterplatte einem SMD- Bestücker zugeführt, der mit einer Saugpipette SMD-Bauelemente auf die Lötflächen der ersten Seite aufsetzt . Nach dem Bestücken wird die Leiterplatte einer Reflowlötstation zugeführt, in der die auf der ersten Seite aufgebrachten Bauele- mente mit den Anschlußflächen verlötet werden. Anschließend wird die Leiterplatte gewendet und einer Kleberstation zugeführt. In der Kleberstation wird mit einer Kanüle, welche von der obenliegenden zweiten Seite der Leiterplatte in die nun über den Bauelementen befindlichen Öffnungen eingeführt wird, Kleber in den Raum zwischen der ersten Seite der Leiterplatte und der Anschlußseite der SMD-Bauelemente eingespritzt. Bei dem derart durchgeführten Verfahren kann der Kleber exakt dosiert werden, so daß er nicht aus dem Raum zwischen Bauelement und Leiterplatte herausfließt. Indem die Bauelemente mit einem einzelnen in der Mitte der Anschlußseite aufgebrachten Klebertropfen an der Leiterplatte festgeklebt werden, wird eine Verunreinigung der an den Seitenrändern angeordneten Lötflächen vermieden. Falls erforderlich wird der Kleber hinter der Kleberstation in einer Här- testation ausgehärtet. Es können aber auch Kleber verwandt werden, die in der Reflowlötstation ausgehärtet werden. Die Leiterplatten werden nun erneut einer Lotpastendruckstation zugeführt und auf den Anschlußflächen der nach oben weisenden zweiten Leiterplattenseite mit Lötpaste bedruckt . Anschließend werden die Leiterplatten in einem Bestücker auf der zweiten Seite mit SMD-Bauelementen bestückt und erneut einer Reflowlötstation zugeführt. Während des nun durchgeführten zweiten Reflowlotschrittes werden die auf die zweite Seite aufgebrachten Bauelemente mit der Leiterplatte verlötet . Dabei wird das Lot der bereits mit den Anschlußflächen der ersten Seite verlöteten Bauelemente erneut aufgeschmolzen, wobei die Klebertropfen zwischen Bauelement und Leiterplatte verhindern, daß sich die SMD-Bauelemente bedingt durch ihre Gewichtskraft von der Leiterplatte ablösen. Nach der Durchführung des zweiten Reflowlotschrittes sind die Bauelemente mit den Anschlußflächen auf beiden Seiten der Leiterplatte verlötet. The method according to the invention can be carried out, for example, in an automatic production line in which the circuit boards on conveyor belts pass through the individual stations one after the other. The printed circuit boards have a first and a second side opposite this, both of which are to be equipped with SMD components. At the locations on the first side of the printed circuit board intended for the application of SMD components, an opening is provided, which extends from the first side to the second side of the printed circuit board. The opening can be designed, for example, as a bore with a diameter of approximately 1 mm. The process begins with a printed circuit board provided on both sides with connection surfaces for SMD components and with the openings described being fed to a solder paste printing station, in which solder paste is applied to the connection surfaces on the first side of the circuit board. The printed circuit board is then fed to an SMD placement device, which attaches SMD components to the soldering areas on the first side using a suction pipette. After assembly, the printed circuit board is fed to a reflow soldering station, in which the components applied on the first side are soldered to the connection areas. The circuit board is then turned over and fed to an adhesive station. In the adhesive station, a cannula, which is inserted from the second side of the printed circuit board above into the openings now located above the components, is used to inject adhesive into the space between the first side of the printed circuit board and the connection side of the SMD components. In the process carried out in this way, the adhesive can be metered exactly so that it does not flow out of the space between the component and the printed circuit board. By gluing the components to the circuit board with a single drop of adhesive applied in the middle of the connection side, contamination of the soldering surfaces arranged on the side edges is avoided. If necessary, the adhesive is cured behind the adhesive station in a hardening station. However, adhesives can also be used that are cured in the reflow soldering station. The Printed circuit boards are now again fed to a solder paste printing station and printed with solder paste on the connection surfaces of the upward-facing second printed circuit board side. The circuit boards are then fitted with SMD components in a placement machine on the second side and again fed to a reflow soldering station. During the second reflow soldering step, the components applied to the second side are soldered to the circuit board. The solder of the components already soldered to the connection faces of the first side is melted again, the drops of adhesive between the component and the circuit board preventing the SMD components from detaching from the circuit board due to their weight. After the second reflow soldering step has been carried out, the components are soldered to the connection areas on both sides of the printed circuit board.

Claims

Ansprüche Expectations
1. Verfahren zum Reflowlöten von mit SMD-Bauelementen bestückten Leiterplatten, bei dem SMD-Bauelemente auf Lötflächen der ersten Seite einer Leiterplatte aufgesetzt werden und in einem ersten Reflowlötschritt mit der Leiterplatte verlötet werden, die Leiterplatte danach mit der ersten Sei- te nach unten gewendet wird und SMD-Bauelemente auf Lötflächen der nun obenliegenden zweiten Seite aufgesetzt werden, die in einem sich daran anschließenden zweiten Reflowlötschritt mit der Leiterplatte verlötet werden, wobei die SMD- Bauelemente auf der ersten Seite vor dem zweiten Reflowlöt- schritt an der ersten Seite der Leiterplatte festgeklebt werden, dadurch gekennzeichnet, daß nach dem ersten Reflowlötschritt ein Kleber von der zweiten Seite der Leiterplatte aus durch jeweils eine Öffnung, welche am Ort der auf die ersten Seite aufgelöteten Bauelemente vorgesehen ist und sich von der ersten Seite bis zur zweiten Seite der Leiterplatte erstreckt, in den Raum zwischen Bauelement und der ersten Seite eingespritzt wird.1. Method for reflow soldering of printed circuit boards equipped with SMD components, in which SMD components are placed on soldering areas of the first side of a printed circuit board and are soldered to the printed circuit board in a first reflow soldering step, the printed circuit board then turned over with the first side down and SMD components are placed on soldering surfaces of the second side, which is now on top, which are then soldered to the circuit board in a second reflow soldering step, the SMD components on the first side before the second reflow soldering step on the first side of the circuit board be glued, characterized in that after the first reflow soldering step an adhesive from the second side of the circuit board through an opening, which is provided at the location of the components soldered onto the first side and extends from the first side to the second side of the circuit board , in the space between building elements t and the first side is injected.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Kleber nach dem Wenden der Leiterplatte mit einer in die Öffnung eingeführten Kanüle direkt in den Raum zwischen der Anschlußseite des SMD-Bauelementes und der ersten Seite der Leiterplatte eingespritzt wird. 2. The method according to claim 1, characterized in that the adhesive is injected after turning the circuit board with a cannula inserted into the opening directly into the space between the connection side of the SMD component and the first side of the circuit board.
EP97943748A 1996-12-13 1997-09-09 Process for reflow soldering of circuit boards fitted with smd components Withdrawn EP0903061A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19651862A DE19651862A1 (en) 1996-12-13 1996-12-13 Process for reflow soldering of printed circuit boards with SMD components
DE19651862 1996-12-13
PCT/DE1997/001997 WO1998026638A1 (en) 1996-12-13 1997-09-09 Process for reflow soldering of circuit boards fitted with smd components

Publications (1)

Publication Number Publication Date
EP0903061A1 true EP0903061A1 (en) 1999-03-24

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EP97943748A Withdrawn EP0903061A1 (en) 1996-12-13 1997-09-09 Process for reflow soldering of circuit boards fitted with smd components

Country Status (8)

Country Link
EP (1) EP0903061A1 (en)
JP (1) JP2000507750A (en)
KR (1) KR19990082161A (en)
CN (1) CN1209942A (en)
CZ (1) CZ251398A3 (en)
DE (1) DE19651862A1 (en)
TW (1) TW383535B (en)
WO (1) WO1998026638A1 (en)

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CN101827501A (en) * 2010-03-31 2010-09-08 伟创力电子科技（上海）有限公司 Through-hole backflow welding technology and relevant template and jig

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CN100455167C (en) * 2005-02-04 2009-01-21 厦门顶尖电子有限公司 Printing-head electromagnet fixing method and device
NL2003341A (en) 2008-08-22 2010-03-10 Asml Netherlands Bv Lithographic apparatus and device manufacturing method.
DE102013002597B3 (en) * 2013-02-14 2014-07-31 Rosenberger Hochfrequenztechnik Gmbh & Co. Kg Method for two-sided assembly of a printed circuit board
AT515446B1 (en) * 2014-03-07 2019-12-15 Zkw Group Gmbh Structuring the solder mask of printed circuit boards to improve the soldering results
DE102018110752A1 (en) * 2018-05-04 2019-11-07 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH Method for producing a connection contact

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN101827501A (en) * 2010-03-31 2010-09-08 伟创力电子科技（上海）有限公司 Through-hole backflow welding technology and relevant template and jig
CN101827501B (en) * 2010-03-31 2012-01-04 伟创力电子科技（上海）有限公司 Through-hole backflow welding technology and relevant template and jig

Also Published As

Publication number Publication date
DE19651862A1 (en) 1998-06-18
CN1209942A (en) 1999-03-03
KR19990082161A (en) 1999-11-25
TW383535B (en) 2000-03-01
WO1998026638A1 (en) 1998-06-18
JP2000507750A (en) 2000-06-20
CZ251398A3 (en) 1999-02-17

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