DE102007021269A1 - Surface mount device repair soldering head and method of operation - Google Patents

Abstract

The invention relates to a repair soldering head (11) for a surface-mounted component. With this repair solder the device can be heated and removed after softening the solder contacts. According to the invention it is provided that the receiving surface (17) for the component is formed by a separating membrane (14) which forms a cavity in which a heat transfer medium (22) can be filled. This cavity also has two independent feeds for the heat transfer medium (22), so that by mixing the heat transfer medium from two supplies (25b, 25a) the desired temperature of the separation membrane can be adjusted for heat transfer to the component to be soldered or brazed. A circulation of the heat transfer medium (22) is made possible by a return (26). Furthermore, the invention relates to methods for soldering in or out of components by means of the repair soldering head according to the invention.

Description

The The invention relates to a repair soldering head for a surface mounted device. The repair soldering head has a receiving surface on the to be desoldered Component can be placed. In addition, the repair solder is provided with a heat source, which heats the receiving surface can be.

A repair soldering head of the type mentioned is, for example, in the US 4,066,204 described. The repair soldering head described there has as a receiving surface for a component to be desoldered a perforated metal plate, which can be placed on the surface of the component to be desoldered. Via a heat element, which serves as a heat source, then a quantity of heat is introduced into the device to be desoldered, resulting in a softening of the solder contacts between the device to be desoldered and the substrate. Because of the holes in the receiving plate, it is possible to seize the component to the recording. For this purpose, the repair soldering head has a vacuum connection, which opens into a cavity formed by the receiving plate. After applying a negative pressure, the repair soldering head can be lifted off the substrate, the vacuum-fixed component remaining on the repair soldering head because of the softened solder joints.

The The object of the invention is a repair soldering head indicate which is comparatively flexible to different Customize use cases.

These The object is achieved according to the invention that the receiving surface is formed by a separating membrane is, which together with a housing structure of the repair soldering on the receiving surface facing away from the separation membrane forms a cavity, wherein the cavity is two independent Inlets and a return for a fluidic Heat transfer medium as a heat source having. Under a fluidic heat transfer medium in the context of the invention is a heat transfer medium to understand which either gaseous or liquid is. It is therefore important that the heat transfer medium is flowable. This ensures advantageous that the heat is well dosed to the to be desoldered Component can be introduced. By providing two independent feeds can continue to be the introduced into the device to be desoldered heat advantageously by mixing two partial lengths of the heat transfer medium be precisely set in a certain ratio. hereby can advantageously be a thermal overload of the Slot and with intended recycling of the desoldered Attention to the component.

When Recording for the device to be desoldered comes a separation membrane used. As a result, the heat transfer medium to circulate cleanly in the cavity formed by the separation membrane, without this would contaminate the slot. The separation membrane has a certain elasticity, the It allows recording with as possible large transfer area for a heat transfer to the to be killed Set up the device. This requires a certain contact pressure.

The Separation membrane may be made of an elastomer such as silicone or of a Metal foil are produced. For the metal foil can In particular, alloys are also used which have a melting range have, which deals with the process-related working temperatures of the repair soldering head overlaps. It can the elastic behavior of the alloy in the melting range to an improvement of the elastic properties of the separation membrane be used. Examples of the latter alloys are SnPb, SnBi, SnSb, SnAg or SnIn.

The gentle way of desoldering makes advantageous the repair soldering more versatile, as well as sensitive Components can be desoldered. Especially the repair soldering can also advantageous for a subsequent insertion of a new component be used, wherein the metered circulation of the heat transfer medium a thermal overload of the einzulötenden Component is prevented.

According to one Embodiment of the invention, it is provided that the separation membrane replaceable is attached to the housing structure. This means that separation membranes held different geometry can be, which in each case on a certain to be desalted Component or group of components with similar Geometry are tailored. This facilitates the conversion the repair soldering head with changing requirements the components to be desoldered advantageous.

Furthermore, according to a particularly advantageous embodiment of the invention, the separation membrane is held in a form variable clamping. On the one hand, the form-adjustable clamping allows adaptation to separation membranes with different geometries as soon as they are replaced. Furthermore, however, a form-adjustable clamping can also be used to deform the separation membrane just used within its elasticity and so a Anpas solution to make the same membrane to different components to be desoldered. The easier adaptability of the repair soldering head to different component geometries advantageously provides a further increase in flexibility in use.

Especially It is advantageous if the form-adjustable clamping consists of a variety of movable fixing pins that the Hold the edge of the separation membrane.

So For example, it is advantageous if the form variable Clamping consists of a plurality of movable fixing pins, which hold the edge of the separation membrane. At these fixation pins suitable mold elements are provided, which are in the edge of the separation membrane engage and fix them in a certain position. Should the shape of the separating membrane can be changed so can the fixing pins are adjusted, thereby adapting the shape the separation membrane to another type of components to be eroded can be done. The flexible use of the Repair soldering is thereby advantageously improved.

A Another possibility is that the separation membrane is rectangular, with two opposite edges with constant distance to each other and the other two edges with variable distance to each other in the clamping are held. This advantageously creates a separation membrane, which adapt to the widely used right angle components leaves. It is about the two edges with variable distance advantageous also the format of easily set to be desoldered components. The heat transfer can always be advantageous on the largest possible proportion of area be extended to be killed of the component.

According to one particular embodiment of the invention, it is provided that the Separating membrane has a vacuum connection with the receiving surface communicated. About the vacuum connection can be advantageous a negative pressure between the separation membrane and the device constructed which leads to adhesion of the component to the receiving surface leads. This ensures that the repair solder Also as a handling tool for the einzulötende or component to be eroded can be used. This facilitates use of the repair solder, with the soldering or desoldering of components in a single operation can be done.

Furthermore, the invention relates to a method for desoldering a surface-mounted component. In this method, a repair solder is placed with a receiving surface on the component to be desoldered, heated the receiving surface by a heat source until softened solder contacts between the device and the surface and then lifted the device from the surface of the substrate component. Such a method is known from the beginning US 4,066,204 known.

Generally The use of such a method is also known for insertion of components. This is a surface mountable component Soldered by a repair soldering head with a receiving surface on the einzuhötende Component is fixed, the device with the repair soldering on the surface of the intended installation location (ie on the substrate member) is placed and the receiving surface heated by a heat source until solder deposits between the component and the surface soften and become solder contacts form.

It Now there is a desire, the method of the type mentioned as possible flexible and gentle for the auszulötenden To apply components.

This object is achieved in that the heat source is a fluid heat transfer medium is used, which is kept in two subsets with different temperatures. In this case, the receiving surface is formed by a separation membrane, which forms a cavity together with a housing structure of the repair soldering on the receiving surface facing away from the side of the separation membrane. To heat the receiving surface suitable proportions are introduced into cavities via two independent feeds from the subsets of the heat transfer medium to set a required temperature and the heat transfer medium returned by a return. By the use of a fluidic heat transfer medium, ie a gas or preferably a liquid, the advantages already mentioned are achieved. In particular, separation membranes of different geometry can be attached to the repair soldering head without endangering reliable heat transfer via the fluidic heat transfer medium. Because the heat transfer medium can easily adapt to the different geometries of the separation membrane. In this way, however, a greater flexibility for the method is achieved, as can be done by using different separation membranes or separation membranes with variable geometry adaptability to different auszulötende or components. At the same time, the process is advantageously also gentler, since the heat transfer medium regardless of the geometry of the separation membrane to egg ner uniform heat transfer without thermal stress peaks can be used.

According to one Embodiment of this invention is provided that for the setting of the required temperature profile a time profile is taken into account. The required temperature profile aims at this ultimately to the setting required for desoldering Temperature at which the solder contacts soften. This can advantageously to be sure that a thermal overload due to too rapid warming of the on or off Component can be avoided. The time profile can be, for example provide a linear heating of the device. there can the creation of the profile depending on heating components are determined from experience. Another possibility is that component or the surface of the substrate on which the device is located should be soldered or soldered with a temperature monitor to provide. Here, for example, a temperature sensor use find, with the help of a control or regulation of the temperature behavior the heating element can be generated.

A Another embodiment of the invention provides that the separation membrane having a vacuum port communicating with the receptacle, wherein the device by applying a vacuum to the vacuum port fixed on the receiving surface and after softening the Lot contacts is lifted off the surface. By providing a vacuum connection can be advantageous, the device very easy to fix on the receiving surface. there moreover, it is also a relative one Gentle handling of the component possible because of mechanical Handling devices can be dispensed with. The vacuum connection makes it advantageous also the Elastizi ity of the separation membrane to use, because by the elastic separation membrane a tight closure ensured between the receiving surface and the device can be.

For the method of brazing results in an advantageous Development of the invention in that after fixing the Component on the receiving surface and before softening the solder contacts the distance of the repair soldering of the Surface under construction of tensile stresses in the separation membrane is enlarged. This will cause biasing produced in the separation membrane, which softens the solder contacts to a relaxation of the separation membrane under magnification the distance of the component to be desoldered from the surface to lead. This can be advantageously avoided that by a contact pressure of the repair soldering on the element to be desoldered this first on the Surface is pressed, wherein the softening solder material would distribute. By the immediate lifting of the component will be an unnecessary pollution of the surface With solder material largely avoided, so that the installation location after the removal of the device can be easily freed from Lotresten can.

Further Details of the invention are described below with reference to the drawing described. Same or corresponding drawing elements are in the individual figures, each with the same reference numerals provided and will only be explained several times, as There are differences between the individual figures. Show it

1 An embodiment of the repair soldering head according to the invention in a schematic cross section,

2 a view into the cavity of the repair soldering according to 1 .

3 and 4 2 shows a schematic cross section and a plan view of another embodiment of the repair soldering head according to the invention,

5 a temperature profile for the operation of the repair soldering head according to the invention and

6 to 8th Selected steps of desoldering as an embodiment of the inventive method.

A repair soldering head 11 according to 1 consists of a housing structure 12 , which may be connected, for example, in a manner not shown to the gripper arm of a placement machine. The housing structure has movable guide pins 13 on, which serve, a separation membrane 14 at the edge 15 to fix. To seal against the environment is still an elastic cuff 16 intended. The separation membrane 14 has an in 1 downward receiving surface 17 on, at a non-illustrated component, which preferably offers a flat surface for this purpose, can be attached. That component can through a vacuum connection 18 , for this purpose with a vacuum pump 19 is connected to the receiving surface 17 be fixed. For this purpose forms part of the separation membrane 14 a suction cup 20 out.

The separation membrane 14 forms together with a cuff 16 and the housing structure a cavity 21 in which a heat transfer medium, for example oil 22 , can be filled. Since the cavity is closed off from the environment, As a result, contamination of the component to be handled and the installation location (substrate, not shown) is avoided.

For generating defined temperature conditions in the cavity 21 can the oil 22 by independent feeds 23a . 23b in the cavity 21 be pumped. There are two pumps for this purpose 24a . 24b available, the oil from two reservoirs 25a . 25b pump. The temperature of the reservoir 25a . 25b Reserved oil is different (for example, room temperature and 200 ° C). By controlling the volume flows of both oils, therefore, a mixing ratio in the cavity 21 be generated with predictable temperature. This allows a predetermined heating state of a on the receiving surface 17 generate fixed component.

To maintain a cycle, the oil becomes 22 over a return 26 by means of a pump 27 into the reservoirs 25a . 25b pumped back. It is about heat exchangers 28a . 28b the temperature prevailing in the reservoirs set again. Accordingly, this either a cooling or heating of the returning oil is necessary.

In 2 is shown as by means of the guide pins 13 an expansion of the diameter of the separation membrane 14 can be done. The pins are mounted radially movable for this purpose in a manner not shown, so that a radial moving apart of their end points to a widening of the edge 15 the separation membrane 14 leads. It can also be seen that in the center of the separation membrane 14 arranged vacuum connection 18 from the elastic deformation of the membrane 14 unaffected. As material for the separation membrane 14 For example, HTV silicone rubber can be used since components made of this material in the stabilized form can have a temperature resistance of up to 300 ° C. A separating membrane of silicone rubber therefore meets the requirements of the application. In addition to a temperature resistance against the introduced heat transfer medium, a chemical resistance to the heat transfer medium is still necessary. For the deformability, a sufficient elasticity must be present. Finally, a sufficient thermal conductivity is required so that the temperature of the heat transfer medium can be transferred to the device.

The 3 and 4 show a different design of the separation membrane. This is in 3 shown in schematic section and in 4 as a top view. The separation membrane 14 has a trough-shaped structure with a rectangular layout. Of the 3 can be seen that the opposite side walls 29 along a wall element 30 are guided and overlap with them, so that a seal comes about. On the other hand, the side walls 29 and the wall element 30 not firmly connected, so that the side wall 29 at a deformation on the wall element 30 can slide along.

The level with the oil 22 is indicated. It is located below the edge of the side wall for reasons of a reliable seal 29 , The remaining construction of the repair soldering head 11 is not shown in more detail, but may be appropriate 1 be constructed.

Of the 4 can be removed, as the adjustment mechanism for the separation membrane 14 is formed in this embodiment. Beside the wall elements 30 which are parallel to each other and at a constant distance in the repair soldering head 11 are arranged, are two more wall elements 31 provided on which the side wall 29 is attached. These wall elements 31 can be between the wall elements 30 shift, causing the separation membrane 14 an elongation undergoes and the repair solder 11 can be adapted to a component of another format.

The separation membrane ( 14 ) according to this embodiment can be formed for example by a highly flexible copper foil. The use of copper has the significant advantage that heat transfer can occur quickly due to the good thermal conductivity of copper. On the other hand, the copper foil on a sufficient elasticity, so that it can adapt well to better heat transfer to the surface of the device.

Of the 5 can be seen how, for example, a temperature profile can be created for a desoldering of a component. If the component is to be supplied, for example, to a new use after the soldering, then the specifications of the manufacturer must be observed with regard to the heating. These consist of a maximum permissible temperature T _max and a permissible heating rate δT / δt. In order to ensure the fastest possible heating of the component despite these specifications, a temperature profile is selected for the heat transfer medium, which is influenced by the specifications of the manufacturer. The temperature of the heat transfer medium is always higher by the amount .DELTA.T than the currently measured temperature of the component, so that a constant heating δT / δt is ensured. When the maximum allowable temperature T _{max of} the device is reached, the temperature of the heat transfer medium is increased by admixing cold heat transfer medium lowered the temperature of the device T _max , so that this temperature is maintained in the device. As soon as the solder joints soften, the component can be removed from the installation site. Subsequently, a further compliance with the temperature T _{max is} no longer necessary.

The 6 to 8th show selected steps of soldering a device 32 , This is with solder contacts 33 on a circuit board 34 attached. In the method step according to 6 becomes the repair soldering head 11 that according to 1 is built on the device 32 placed. The vacuum connection 18 is evacuated, so in the bell 20 a negative pressure is created, which is the separation membrane 14 on the device 32 fixed. The separation membrane has up to the clamping point in repair soldering 11 a height h.

In the method step according to 7 becomes the repair soldering head 11 raised by the amount x. It turns out that due to the elasticity of the separation membrane 14 and due to the firm concern of the separation membrane 14 on the device 32 an elongation of the separation membrane in the direction of the height h by the amount x occurs. As a result, tensile stresses are induced in the separation membrane, due to which the component 32 a tensile force Z from the circuit board 34 is subjected to. It also shows that by the elongation of the separation membrane by the amount x the suction cup 20 gets a slightly larger volume.

Of the 8th can be seen that when softening the solder contacts 33 due to the heat input through the repair soldering head 11 the impressed tensile force Z (see 7 ) to a lifting of the device 32 leads. Here, the distance of the bottom of the device 32 from the circuit board 34 increased by the amount x, so that the solder contacts 33 to the circuit board 34 be solved. This reduces the height of the suction cup back to h. Solder remains on the circuit board 35 , which must be removed in a subsequent step (not shown) of the circuit board, if the slot is to be prepared for receiving a new component. The component 32 can be removed from the plate with the repair soldering head and, for example, disposed of or reused.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 4066204 [0002, 0014]

Claims (11)

Repair soldering head ( 11 ) for a surface-mounted component ( 32 ) - with a receiving surface ( 17 ) on the component to be desoldered ( 32 ) and - with a heat source, with which the receiving surface ( 17 ), characterized in that - the receiving surface ( 17 ) through a separating membrane ( 14 ), which together with a housing structure ( 12 ) of the repair soldering head ( 11 ) on the receiving surface facing away from the side of the separation membrane a cavity ( 21 ) where - the cavity ( 21 ) two independent feeds ( 23a . 23b ) and a return ( 26 ) for a fluidic heat transfer medium ( 22 ) as a heat source. Repair soldering head ( 11 ) according to claim 1, characterized in that the separating membrane ( 14 ) replaceable on the housing structure ( 12 ) is attached. Repair soldering head ( 11 ) according to claim 1 or 2, characterized in that the separating membrane ( 14 ) is held in a form variable clamping. Repair soldering head ( 11 ) according to claim 3, characterized in that the form-variable clamping of a plurality of movable guide pins ( 13 ), which surrounds the edge of the separation membrane ( 14 ) hold. Repair soldering head ( 11 ) according to claim 3, characterized in that the separating membrane ( 14 ) is rectangular, wherein two opposite edges are kept at a constant distance from each other and the other two edges with a variable distance from each other in the clamping. Repair soldering head ( 11 ) according to one of the preceding claims, characterized in that the separating membrane ( 14 ) a vacuum connection ( 18 ), which is connected to the receiving surface ( 17 ) communicates. Method for desoldering a surface-mounted component ( 32 ), in which - a repair soldering head ( 11 ) with a receiving surface ( 17 ) on the component to be desoldered ( 32 ), - the receiving surface ( 17 ) is heated by a heat source until solder contacts ( 33 ) between the component ( 32 ) and the surface soften and - the device ( 32 ) is lifted off the surface, characterized in that - as the heat source, a fluidic heat transfer medium ( 22 ) is used, which is kept in two subsets with different temperatures, and - the receiving surface ( 17 ) through a separating membrane ( 14 ), which together with a housing structure ( 12 ) of the repair soldering head ( 11 ) on the receiving surface ( 17 ) facing away from the separation membrane ( 14 ) a cavity ( 21 ), wherein for heating the receiving surface ( 17 ) - via two independent feeds ( 23a . 23b ) of the subsets of the heat transfer medium ( 22 ) to set a required temperature suitable proportions in the cavity ( 21 ) and - the heat transfer medium ( 22 ) by a return ( 26 ) again the cavity ( 21 ) leaves. Method for inserting a surface-mountable component ( 32 ), in which - a repair soldering head ( 11 ) with a receiving surface ( 17 ) on the building element to be killed ( 32 ), - the component ( 32 ) with the repair soldering head ( 11 ) is placed on the surface of the intended installation location and - the receiving surface ( 17 ) is heated by a heat source until solder deposits between the component ( 32 ) and the surface soften and form solder contacts, characterized in that - as a heat source, a fluidic heat transfer medium ( 22 ) is used, which is kept in two subsets with different temperatures, and - the receiving surface ( 17 ) through a separating membrane ( 14 ), which together with a housing structure ( 12 ) of the repair soldering head ( 11 ) on the receiving surface ( 17 ) facing away from the separation membrane ( 14 ) a cavity ( 21 ), wherein for heating the receiving surface ( 17 ) - via two independent feeds ( 23a . 23b ) of the subsets of the heat transfer medium ( 22 ) to set a required temperature suitable proportions in the cavity ( 21 ) and - the heat transfer medium ( 22 ) by a return ( 26 ) again the cavity ( 21 ) leaves. Method according to claim 7 or 8, characterized that for setting the required temperature profile a time profile is taken into account. Process according to Claim 9, characterized in that the separating membrane ( 14 ) a vacuum connection ( 18 ), which with the Aufnahmeflä che ( 17 ) communicates with the device ( 32 ) by applying a vacuum to the vacuum connection ( 18 ) is fixed on the receiving surface and lifted after softening the solder contacts from the surface. Method for desoldering according to claim 10, characterized in that after the fixing of the component ( 32 ) on the receiving surface and before softening the solder contacts the distance of the repair soldering head ( 11 ) from the surface with the formation of tensile stresses in the separation membrane ( 14 ) is increased.