Dual-nozzle soldering / desoldering tool for hot gas rework station of ball matrix components

Abstract

The invention relates to a soldering / desoldering tool (200) intended to be removably mounted on a movable arm of a hot gas rework station for BGA components, said tool (200) comprising a support plate (210) intended to be fixed on said arm and a first tubular guide nozzle (220) extending perpendicularly to said plate from and along the peripheral perimeter of a first corresponding window provided in said plate; said tool also comprising at least a second tubular guide nozzle (230) extending perpendicularly to said plate from and along the peripheral perimeter of a second corresponding window provided in said plate, said nozzles being capable, in the configuration mounted on said tool on said arm, of ensuring the simultaneous guidance of two streams of heating gas to two respective said BGA components arranged close to each other on a printed circuit board.Figure to be published with the abbreviation: Fig. 3.

Description

Title of the invention: Dual-nozzle soldering / desoldering tool for hot gas rework station of ball matrix components. Technical field

[0001] The present invention relates to the field of hot gas rework stations for ball matrix (BGA) electronic components.

[0002] It relates in particular to a double nozzle welding / desoldering tool for such a hot gas rework station. Previous technique

[0003] Surface-mount devices, commonly referred to by the acronym SMD (for "Surface Mounted Device"), are at the heart of technological evolution in the field of electronics.

[0004] Unlike traditional through-hole components commonly referred to by the acronym THD (for "Through-Hole Devices"), SMDs are directly mounted and soldered onto the surface of printed circuit boards commonly referred to by the acronym PCB (for "Printed Circuit Board").

[0005] This mounting method offers several advantages, including increased mounting density, better electrical performance due to shorter signal paths, and compatibility with automated production processes, which reduces manufacturing costs.

[0006] Among the different forms of SMD, components with a ball matrix type package and commonly referred to by the acronym BGA (for "Bail Grid Array" in English) are distinguished by their ability to support a high number of connections in a small space.

[0007] The electrical connections of a BGA component are made via solder balls arranged in a grid on the underside of the package. This arrangement ensures better electrical performance thanks to short and direct connections, reducing inductance and parasitic resistance. It also allows for better heat dissipation, which is crucial for high-power and high-frequency components.

[0008] Furthermore, solder balls, being less likely to deform or break compared to the legs of traditional components, increase the reliability of electrical connections, particularly in environments subject to mechanical and thermal stresses.

[0009] However, BGA components have certain drawbacks. For example, replacing such a defective BGA component on a PCB requires the use of a hot gas BGA rework station (or "BGA Rework Station" in English).

[0010] Such a rework station includes a support table integrating a lower heating module on which the PCB is placed, and a movable arm mounted above this table carrying a removable soldering / desoldering tool.

[0011] This welding / desoldering tool classically comprises a support plate intended to be fixed on said movable arm and a guide nozzle extending perpendicularly to said plate from and along the peripheral perimeter of a corresponding window provided in this plate.

[0012] The guide nozzle is generally in the form of a metal tube with a rectangular or square cross-section, the dimensions of which are specifically adapted to those of the BGA component to be removed.

[0013] Once the PCB is positioned on the support table, the movable arm is moved so that this guide nozzle is positioned vertically above the BGA component with its lower end located a few millimeters from the PCB.

[0014] A stream of hot gas is then blown through an upper heating module inside this nozzle which will guide it to the BGA component.

[0015] After the solder balls have been reflowed, the BGA component is drawn in by a suction pipette extending inside and along the guide nozzle. This component then detaches from the PCB and attaches itself to the lower end of this suction pipette.

[0016] Although the use of such a hot gas soldering / desoldering tool makes it possible to ensure relatively localized heating in the area of ​​the BGA component to be removed, the components located on the PCB near this area are also subjected to significant thermal stress which may lead to the reflowing of some solder joints of these components and / or their deterioration.

[0017] These risks are all the greater when several BGA components located close to each other on the same PCB must be removed successively and replaced.

[0018] In order to reduce the thermal stress of the other components located in the area concerned of the PCB, document CN 214544966 U proposes to provide an external cover surrounding the guide nozzle so as to constitute between this nozzle and this cover a thermal dissipation chamber.

[0019] Unfortunately, the effectiveness of this type of cover proves to be very limited in practice. Description of the invention

[0020] The present invention therefore aims to improve the situation.

[0021] For this purpose, it proposes a soldering / desoldering tool intended to be mounted removably on a mobile arm of a hot gas rework station for ball matrix components, said tool comprising a support plate intended to be fixed on said arm and a first tubular guide nozzle extending perpendicularly to said plate from and along the peripheral perimeter of a first corresponding window provided in this plate.

[0022] According to the invention, said tool also includes at least one second tubular guide nozzle extending perpendicularly to said plate from and along the peripheral perimeter of a second corresponding window provided in said plate, said nozzles being able, in the configuration mounted on said tool on said arm, to ensure the simultaneous guidance of two streams of heating gas to two said respective ball matrix components arranged close to each other on a printed circuit board.

[0023] The soldering / desoldering tool according to the invention thus makes it possible to divide by two the number of successive heating cycles which the printed circuit board undergoes in the area of ​​implantation of two defective ball matrix components to ensure their removal and their replacement by identical functional components, so as to considerably reduce the risk of generating collateral damage on other components implanted on this board.

[0024] Furthermore, the use of such a tool makes it possible to obtain significant productivity gains by halving or almost halving the time required for an operator to remove these two defective ball matrix components and replace them.

[0025] In order to ensure homogeneous heating of the two defective components to be removed, said tubular guide nozzles advantageously have an identical rectangular or square cross-section.

[0026] In the case of two defective components arranged coplanarly on the electronic board and in order that said tubular guide nozzles come simultaneously almost into contact with these components, the latter may preferentially extend over an identical length from said plate with their lower ends which are located in the same plane parallel to this plate.

[0027] In the case of two defective components arranged at two different levels on the electronic board, and in order for said tubular guide nozzles to come into almost simultaneous contact with these components, the latter may preferentially extend over different lengths from said plate with their lower ends which are located in two parallel planes to each other and to this plate.

[0028] In order to allow the removal of defective components after desoldering, the soldering / desoldering tool according to the invention advantageously comprises two gripping devices each coupled to a corresponding tubular guide nozzle and each comprising a respective suction pipette extending inside and along this nozzle while being centered on its axis.

[0029] For reasons of ease of manufacture and cost, each said aspiration pipette is carried, near its upper end protruding through a corresponding window of the plate, by a respective support bar comprising a central portion partially covering said window and two lateral portions resting against the upper face of said plate, on either side of this window, and each being fixed to this plate.

[0030] For reasons of simplicity and convenience in both manufacture and use, the upper ends of said suction pipettes protruding through said windows of said plate are preferably fluidly connected to each other by a connecting member provided with a connector allowing the connection of a conduit connected to a vacuum pump system.

[0031] In order to ensure effective gripping of the components, each said suction pipette is provided, at its protruding lower end of a corresponding said guide nozzle, with a flexible tip intended to stick by suction against a said bead matrix component.

[0032] In order to optimize this gripping, each gripping device advantageously includes worm screw adjustment means allowing fine adjustment of the vertical positioning of its aspiration pipette with respect to a corresponding guide nozzle.

[0033] Finally, and in order to guarantee perfect centering of their tip, each said aspiration pipette includes, near its lower end, a cross-shaped centering element whose four free ends come into contact with the four internal edges of a corresponding guide nozzle. Brief description of the drawings

[0034] The description of the invention will now be continued by a detailed description of several embodiments, given below by way of illustration but not limitation, with reference to the accompanying drawings, on which: - [Fig.1] represents a top view of a printed circuit board (PCB) including two defective ball-array components (BGA) located close to each other and which must be replaced; - [Fig.2] is a three-quarter perspective top view of a known hot gas rework station intended to perform the removal and replacement of defective BGA components on PCBs; - [Fig.3] represents a three-quarter perspective view from below of a welding / desoldering tool according to a preferred embodiment of the invention for a rework station such as that of [Fig.2]; - [Fig.4] is a three-quarter perspective top view of the welding / desoldering tool of [Fig.3]; - [Fig.5] represents a cross-sectional view of the welding / desoldering tool of [Fig.3]; - [Fig. 6] is a simplified view illustrating a simultaneous desoldering operation of the two defective ball-array (BGA) components arranged on the PCB of [Fig. 1] via a hot gas rework station such as that of Fig. 2 equipped with the soldering / desoldering tool of Figures 2 to 5; and - [Fig.7] represents a side elevation view of a welding / desoldering tool according to an alternative embodiment of the invention. Description of the implementation methods

[0035] Fig. 1 represents an electronic printed circuit board or PCB 2 on which are soldered a multitude of electronic components, including in particular two ball matrix or BGA 3, 4 components arranged close to each other and which must be replaced because they are defective.

[0036] These BGA 3, 4 components are in this case identical and for example made up of two double data rate memory modules commonly referred to by the acronym DDR (for "Double Data Rate" in English).

[0037] Fig. 2 shows a hot gas rework station 100 for removing and replacing defective BGA components on a printed circuit board.

[0038] This type of rework station is well known to those skilled in the art and is marketed in particular by the German company FINETECH under the name Fineplacer® Coreplus.

[0039] With reference to this [Fig.2], such a rework station 100 classically comprises a horizontal platform forming a base 110 on which is mounted movably, via an air cushion system, a support table 120 whose relative position vis-à-vis this platform 110 can be precisely adjusted using micrometric screws 130.

[0040] The support table 120 includes two parallel rails 121 whose spacing is adjustable so as to allow a firm clamping of an electronic printed circuit board (or PCB) 140 between these two rails 121.

[0041] This support table 120 also incorporates a first, non-visible, lower heating module arranged beneath the rails 121, enabling preheating from below of a localized area of ​​the board 140 or its entire surface. This lower heating module uses heating elements such as electric resistors, hot air blowers, or infrared emitters distributed over the surface of the support table 120.

[0042] Such a rework station 100 further comprises an arm 150 extending above the platform 110 and mounted pivotally relative to the latter about a transverse horizontal axis. This arm 150 incorporates a second, non-visible, upper forced convection heating module and has at its distal end a head 151 on which a soldering tool / soldering 160 can be removably mounted, including a guide nozzle 161 for selectively heating a defective BGA component 141 present on the board 140 until the reflow temperature of these solder balls is reached.

[0043] This upper heating module includes heating elements such as electric resistances or infrared emitters through which air or an inert gas such as an air / nitrogen mixture is pulsed by a blower or fan through a blower mouth opening at the inlet opening of this nozzle 161.

[0044] The soldering / desoldering arm 150 is mobile between a raised rest position illustrated by [Fig.2] and a lowered position in which the guide nozzle 161 is positioned vertically above the defective BGA component 141 to be removed from the board 140 and so that its lower end is located a few millimeters from the PCB 140.

[0045] Such a rework station 100 may also include an observation device 170 surmounting the platform 110 and allowing an operator to precisely adjust the position of the card 140 on the support table 120 so as to ensure that the guide nozzle 161 comes perfectly centered on the defective BGA component 141 when the articulated arm 150 is lowered.

[0046] Figures 3 to 5 represent a soldering / desoldering tool according to a preferred embodiment of the invention 200 intended to be removably mounted on the support head 151 of the mobile arm 150 of a hot gas rework station such as 100, so as to allow the simultaneous removal of the two defective ball matrix components 3, 4 present on the PCB 2 of [Fig.1], and subsequently the simultaneous installation on this board 2 of two functional replacement BGA components.

[0047] In the following description, when certain constituent elements of tool 200 are described with absolute position qualifiers (such as the terms "front", "rear", "up", "down", "left", "right", etc.), relative position (such as the terms "above", "below", "superior", "inferior", etc.) or orientation (such as the terms "vertical", "horizontal", etc.), reference will be made to the service position of this tool 200 which it takes in its configuration mounted on the arm 150 of the recovery station 100 after the lowering of this arm 150.

[0048] With reference to figures 3 and 4, the welding / desoldering tool 200 comprises a horizontal support plate 210 in the central part of which two windows 211, 212 are provided.

[0049] This tool 200 also includes two tubular guide nozzles 220, 230 extending perpendicularly to this support plate 210 and below it, each from the peripheral perimeter of a corresponding window 211, 212.

[0050] The support plate 210 advantageously has the shape of a regular polygon (that is, a polygon whose edges are all the same length and whose internal angles are all equal). Such a shape makes it possible to position the tool 200 in several predetermined angular positions by bracing it with one of its edges against a shoulder provided on the head 151 of the arm 150.

[0051] In this case and as illustrated by figures 3 and 4, this support plate 210 is in the form of a regular hexagon, which allows it to be fixedly mounted on the arm 150 according to six predetermined angular indexing positions spaced 60° apart.

[0052] The support plate 210 also has several peripheral circular indentations 213, each located near one of its edges and symmetrically opposite each other in pairs with respect to the center of this plate 210.

[0053] Two of these opposing impressions 213 are intended to cooperate with locking pins not shown provided on the head 151 of the arm 150 so as to ensure the locking of the tool 200 in the chosen position.

[0054] To ensure their durability and resistance to the high temperatures they are subjected to, the support plate 210 and the nozzles 220, 230 are preferably made of a metallic material such as stainless steel or anodized aluminum. Each nozzle 220, 230 is then attached to the support plate 210 by welding, for example, via a weld bead along the upper peripheral circumference of the nozzle 220, 230, or by means of a plurality of spot electric welds (SEWs) distributed along this peripheral circumference.

[0055] Advantageously produced by forming / welding or by extrusion, the two nozzles 220, 230 preferably have an identical rectangular cross-section or square and whose dimensions correspond to those of the two defective BGA components 3, 4 to be removed from PCB 2.

[0056] The spacing between the nozzles 220, 230 and their relative orientation (here, at 90° to each other) are also predetermined so that the latter can be arranged simultaneously in line with these two BGA components 3, 4 as illustrated by [Fig.6].

[0057] In order that their respective lower ends come into position simultaneously almost in contact with the PCB 2 when the arm 150 is moved into its lowered position, these two nozzles 220, 230 extend over an identical length from the plate 210 with their lower ends which are located in the same plane parallel to this plate 210.

[0058] The tool 200 further comprises two gripping devices each coupled to a corresponding nozzle 220, 230.

[0059] As illustrated by [Fig.5], each gripping device comprises a respective suction pipette 221, 231 extending inside along this nozzle 220, 230 while being centered on its axis.

[0060] With reference to Figures 4 and 5, each aspiration pipette 221, 231 is carried, near its upper end protruding through a corresponding window 211, 212 of the plate 210, by a respective support bar 222, 232 comprising a central portion 222A, 232A partially covering said window 211, 212 and two lateral portions 222B, 232B resting against the upper face of the plate 210, on either side of this window 211, 212, and each being fixed by screwing to this plate 210 via a respective screw V whose head is visible on [Fig.3].

[0061] Still with reference to this [Fig.5], the upper ends of these suction pipettes 231, 241 are fluidly connected to each other by a connecting member 250 provided with a female connector 251 allowing the connection of a conduit not shown connected to a vacuum pump system.

[0062] As can be seen in Figures 3 and 5, each suction pipette 221, 231 is further provided at its lower protruding end of a corresponding nozzle 220, 230 of a flexible tip 221 A, 231 A, conventionally made of silicone or of an elastomeric material such as rubber, and intended to stick by suction against a corresponding defective BGA component 3, 4 after the melting of the solder balls so as to allow its removal when the arm 150 returns to its raised position.

[0063] The gripping device associated with each nozzle 220, 230 may further include worm screw adjustment means R allowing fine adjustment of the vertical positioning of its suction pipette 221, 231 vis-à-vis this nozzle 220, 230, so as to ensure good gripping of the BGA component 3, 4 by its tip 221 A, 231 A.

[0064] Advantageously and with reference to Figures 3 and 5, each aspiration pipette 221, 231 may also include, near its lower end, a cross-shaped centering member 221 B, 231B whose four free ends come into contact with the four internal edges of the corresponding nozzle 220, 230 so as to guarantee perfect centering of the tip 221A, 231A of this pipette 221, 231 with respect to the lower end of this nozzle 220, 230.

[0065] We will now describe the process of simultaneous removal of the two defective B GA components 3, 4 implanted on the PCB 2 by means of a rework station such as 100, equipped with a soldering / desoldering tool 200 according to the invention mounted on its arm 150.

[0066] To do this, the PCB 2 is first loaded onto the support table 120, held clamped between the two rails 121. This support table 120 is then finely positioned vis-à-vis the platform 110 via the air cushion system and the micrometric screws 130 as well as with the help of the observation device 170, so as to ensure that the nozzles 220, 230 will align perfectly vertically with these two BGA components 3, 4 when the arm 150 is lowered against this PCB 2.

[0067] This arm 150 is then tilted towards its lowered position so that the two nozzles 220, 230 come to be positioned simultaneously in line with the two BGA components 3, 4 with their lower ends which are almost in contact with the PCB 2 as illustrated by [Fig.6].

[0068] A preheating of the PCB 2 is then carried out via the lower heating module before two streams of hot gas are blown via the upper heating module into the nozzles 220, 230 so that the latter guide this hot gas to the BGA components 3, 4.

[0069] The rework station 100 then follows a preprogrammed heating profile allowing the solder balls of these BGA components 3, 4 to reach their reflow temperature.

[0070] After the remelting of these solder balls, the vacuum pump system is activated and the arm 150 is lowered very slightly so that the soft tips 221 A, 231A of the suction pipettes 221, 231 come to stick simultaneously on these BGA components 3, 4.

[0071] The arm 150 can then be raised, which leads to the removal of the BGA components 3, 4 from the PCB 2 (the latter remaining stuck to the flexible tips 221 A, 231A of the suction pipettes 221, 231).

[0072] Tool 200 can also be used to simultaneously solder two replacement functional BGA components onto PCB 2.

[0073] Figure 7 represents a welding / desoldering tool 200' according to an alternative embodiment of the invention. In the following and in Figure 7, the same reference numerals have been used for elements identical to tool 200, and a prime number has been added for similar elements.

[0074] The tool 200' is similar to the tool 200 described previously, except that the two nozzles 220', 230' extend over different lengths from the plate 210 with their lower ends which are located in two planes parallel to each other and to this plate 210.

[0075] It is understood that such a tool 200' will make it possible to ensure the removal or installation of BGA components located at different levels on the same PCB.

[0076] According to other embodiments not shown, the tool guide nozzles according to the invention could have sections of different dimensions corresponding to those of BGA components of also different sizes.

[0077] In order for the reflowing of the solder balls of the BGA components to occur simultaneously, such a configuration would however require the provision of two separate upper heating modules controlled according to two different heating profiles.

[0078] According to yet other unrepresented embodiments, the welding / desoldering tool could comprise a number of nozzles greater than two and for example equal to three or four.

[0079] Generally, the number and dimensions of these nozzles will be dictated by the location and size of the BGA components to be replaced as well as by the dimensions of the blower mouth integrated into the arm 150.

[0080] Finally, it should be noted that the present invention is not limited to the embodiments described and represented, but also encompasses all variants of execution within the reach of a person skilled in the art.

Claims

Demands

1. Soldering / desoldering tool (200; 200') intended to be removably mounted on a movable arm (150) of a hot gas rework station (100) for ball matrix components (3, 4), said tool (200; 200') comprising a support plate (210) intended to be fixed on said arm (150) and a first tubular guide nozzle (220; 220') extending perpendicularly to said plate (210) from and along the peripheral perimeter of a first corresponding window (211) provided in said plate (210); characterized in that said tool (200; 200') also comprises at least one second tubular guide nozzle (230; 230') extending perpendicularly to said plate (210) from and along the peripheral perimeter of a second corresponding window (212) formed in said plate (210), said nozzles (220, 230; 220', 230') being suitable, in the mounted configuration of said tool (200;200') on said arm (150), to ensure the simultaneous guidance of two heating gas flows to two respective ball matrix components (3, 4) arranged close to each other on a printed circuit board (2).;

2. Welding / desoldering tool (200; 200') according to claim 1, characterized in that said tubular guide nozzles (220, 230; 220', 230') have an identical rectangular or square cross-section.

3. Welding / desoldering tool (200) according to any one of claims 1 or 2, characterized in that said tubular guide nozzles (220, 230) extend over an identical length from said plate (210) with their lower ends which are located in the same plane parallel to this plate (210).

4. Welding / desoldering tool (200') according to any one of claims 1 or 2, characterized in that said tubular guide nozzles (220', 230') extend over different lengths from said plate (210) with their lower ends which are located in two planes parallel to each other and to this plate (210).

5. Welding / desoldering tool (200; 200') according to any one of claims 1 to 4, characterized in that it comprises two gripping devices each coupled to a corresponding tubular guide nozzle (220, 230; 220', 230') and each comprising a respective aspiration pipette (221, 231) extending inside and along this nozzle (220, 230; 220', 230') being centered on its

6. axis. Welding / desoldering tool (200; 200') according to claim 5, characterized in that each said suction pipette (221, 231) is carried, near its upper end projecting through a corresponding window (211, 212) of the plate (210), by a respective support bar (222, 232) comprising a central portion (222A, 232A) partially covering said window (211, 212) and two lateral portions (222B, 232B) resting against the upper face of said plate (210), on either side of this window (211, 212), and each being fixed to this plate (210).

7. Welding / desoldering tool (200; 200') according to any one of claims 5 or 6, characterized in that the upper ends of said suction pipettes (221, 231) protruding through said windows (211, 212) of said plate (210) are fluidly connected to each other by a connecting member (250) provided with a connector (251) allowing the connection of a conduit connected to a vacuum pump system.

8. Welding / desoldering tool (200; 200') according to any one of claims 5 to 7, characterized in that each said suction pipette (221, 231) is provided, at its lower end projecting from a corresponding said guide nozzle (220, 230), with a flexible tip (221 A, 231 A) intended to stick by suction against a said ball matrix component (3, 4).

9. Welding / desoldering tool (200; 200') according to any one of claims 5 to 8, characterized in that each gripping device includes worm gear adjustment means (R) allowing fine adjustment of the vertical positioning of its suction pipette (221, 231) vis-à-vis a corresponding guide nozzle (220, 230).

10. Welding / desoldering tool (200; 200') according to any one of claims 5 to 9 depending on claim 2, characterized in that each said suction pipette (221, 231) comprises, near its lower end, a cross-shaped centering member (221B, 23IB) whose four free ends come into contact with the four internal edges of a corresponding guide nozzle (220, 230).

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