TOPOGRAPHY-BASED DEPOSITION HEIGHT ADJUSTMENT

Abstract

A method for mounting a component (100) on a workpiece (106), the method comprising obtaining information regarding a surface topography of at least one of a mounting surface (102) of the component and a local surface (108) of the workpiece onto which the component is to be mounted. The method further comprises forming a plurality of deposits (110) of a viscous medium on at least one of the mounting and local surfaces, wherein each of the plurality of deposits has a height (/½, /½, h3) based on the obtained information, and is formed by individually applying at least one droplet (234) of the viscous medium (232) using non-contact dispensing. The method further comprises placing the component on the substrate, such that the plurality of deposits of viscous medium forms a connection between the component and the workpiece.

Claims

1. A method for mounting a component on a workpiece, the method comprising: obtaining information regarding a surface topography of a first surface of said component and a local surface of said workpiece onto which said component is to be mounted; forming a plurality of deposits of a viscous medium on at least one of said first surface and said local surface, wherein each of the plurality of deposits has a height based on the obtained information, and is formed by applying at least one droplet of the viscous medium using non-contact dispensing; and placing the component on the substrate, such that said plurality of deposits of viscous medium forms a connection between said component and said workpiece.

2. The method of claim 1, wherein said obtaining information comprises performing surface measurements on at least one of said first surface and said local surface.

3. The method of claim 1, wherein said obtaining information comprises retrieving information of a surface topography of at least one of said first surface and said local surface from a storage unit.

4. The method of claim 1, wherein the forming of the plurality of deposits is followed by applying further viscous medium to at least one of said plurality of deposits using non-contact dispensing.

5. The method of claim 4, wherein said obtaining information comprises, while forming the plurality of deposits, performing measurements of the at least one of the first surface and the local surface on which said plurality of deposits are formed.

6. The method of claim 1, further comprising: after placing said component on the workpiece, applying energy to the deposits, component and/or the workpiece to process said deposits; wherein said information regarding a surface topography comprises information regarding a predicted change in topography of at least one of said first surface and said local surface resulting from the application of energy.

7. The method of claim 1, wherein said non-contact dispensing includes jet printing or laser induced forward transfer, LIFT.

8. The method of claim 1, wherein said component is an electrical component.

9. The method of claim 8, wherein said viscous medium comprises an electrically conductive material.

10. A system for depositing a viscous medium, said system comprising: a non-contact dispensing device arranged for applying droplets of a viscous medium onto a first surface of a component to be mounted on a workpiece or a local surface (108) of said workpiece onto which said component is to be mounted; and a control unit adapted to: obtain information regarding a surface topography of said first surface and said local surface of said workpiece; determine, based on said information, heights h.sub.1; h.sub.2; h.sub.3 of a plurality of deposits of a viscous medium that is to be formed on at least one of said first surface and said local surface, such that said plurality of deposits forms a connection between said component and said workpiece upon placing said component on the workpiece; and cause the non-contact dispensing device to form each of the plurality of deposits of viscous medium by applying at least one droplet of the viscous medium using non-contact dispensing.

11. The system of claim 10, wherein said control unit is in communicative contact with a storage unit comprising information regarding a surface topography of at least one of a first surface of an component and a local surface of a workpiece.

12. The system of claim 10, wherein said non-contact dispensing device is selected from a jet printing device and a LIFT device.

13. The system of claim 10, further comprising a surface measurement device configured to perform measurements of at least one of said first surface and said local surface.

14. The system of claim 13, wherein said surface measurement device is arranged to perform measurements of said at least one of said first surface and said local surface while said non-contact dispensing device applies droplets of the viscous medium onto said at least one of said mounting surface and said local surface.

15. A storage medium comprising instructions which, when carried out by a control unit of a system for depositing a viscous medium, will bring a control unit of the system to: obtain information regarding a surface topography of at least one of a first surface of a component and a local surface of a workpiece onto which said component is to be mounted; and determine, based on said information, heights of a plurality of deposits of a viscous medium that is to be deposited on at least one of said first surface and said local surface, such that said plurality of deposits forms a connection between said component and said workpiece upon placing said component on the workpiece; and will bring a non-contact dispensing device of the system to form the plurality of deposits, based on the determined heights, on at least one of said first surface and said local surface by applying at least one droplet of the viscous medium using non-contact dispensing.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0095] Exemplifying embodiments will now be described in more detail, with reference to the following appended drawings:

[0096] FIG. 1 is an illustration of a component and a workpiece, in accordance with some embodiments;

[0097] FIG. 2 is a cross-section of a component and a local surface of a workpiece, in accordance with some embodiments;

[0098] FIG. 3 is an illustration of a local surface of a workpiece on which a plurality of deposits has been formed, in accordance with some embodiments;

[0099] FIG. 4 is a cross-section of a component and a local surface of a workpiece, in accordance with some embodiments;

[0100] FIG. 5 is an illustration of a local surface of a workpiece on which a plurality of deposits has been formed, in accordance with some embodiments;

[0101] FIGS. 6a-c are illustrations of a component mounted on a local surface of a workpiece, in accordance with some embodiments;

[0102] FIG. 7 is a further illustration of a component mounted on a local surface of a workpiece, in accordance with some embodiments;

[0103] FIG. 8 is a schematic illustration of a system for depositing a viscous medium, in accordance with some embodiments;

[0104] FIG. 9 is a schematic illustration of a system for depositing a viscous medium, in accordance with some embodiments.

[0105] As illustrated in the figures, the sizes of the elements and regions may be exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of the embodiments. Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION

[0106] Exemplifying embodiments will now be described more fully hereinafter with reference to the accompanying drawings in which currently preferred embodiments are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0107] With reference to FIG. 1, a component 100 and a workpiece 106, in accordance with some embodiments, will be described.

[0108] FIG. 1 shows a component 100 about to be mounted on a local surface 108 of a workpiece 106. The component 100 has a first surface 102 comprising a plurality of contact pads 104. The contact pads 104 are arranged in a grid pattern on the first surface 102, although not all pads 104 are visible in FIG. 1. For example, the component 100 may comprise a ball grid array (BGA).

[0109] The component 100 is warped such that the corners of the component 100 are slightly curved away from the workpiece 106. This warpage has been exaggerated for illustrative purposes.

[0110] On the workpiece 106, a plurality of deposits 110 of a viscous medium has been formed on the local surface 108. These deposits 110 are formed in positions matching the positions of the contact pads 104 of the component 100. When the component 100 is mounted on the local surface 108 of the workpiece 106, the deposits 110 line up with the contact pads 104. After mounting, the viscous medium of the deposits 110 holds the component 100 in place. However, as the component 100 is warped, the first surface 102 is not parallel with the local surface 108. The deposits 110 depicted in FIG. 1 are all of the same height, thus, since the distance between the first surface 102 of the component 100 and the local surface 108 of the workpiece 106 varies, not all deposits 110 may reach its corresponding contact pad 104. Gaps may therefore be formed between a deposit 110 and its corresponding contact pad 104, which may result in the component 100 not being properly held in place. In embodiments in which the component 100 is electric or optical, the deposits 110 of viscous medium may have the purpose of conveying electrical or optical signals between the component 100 and the workpiece 106. In such embodiments, a gap between the deposit 110 and the contact pad 104 or contact point may lead to functionality issues.

[0111] It will be appreciated that not all components have contact pads 104 extending from the first surface 102 as illustrated in FIG. 1. Some components have other types of contact points, and other components may not have specific contact points at all.

[0112] Further, in FIG. 1 and some following examples, only the component 100 is curved/warped. It will, however, be appreciated that the workpiece 106 and specifically the local surface 108 thereof, may also be warped. In some situations, both the component and the workpiece may be warped/curved, and in other situations only the component or only the workpiece may be warped. Further, the first surface of the component and/or local surface of the workpiece may comprise structures including for example holes, ridges, bumps or valleys.

[0113] With reference to FIGS. 2 and 3, analysis of the topography of the first surface 102 of the component 100a, and formation of deposits 110a-c on the workpiece 106, in accordance with some embodiments, will be described.

[0114] FIG. 2 is an illustration of a component 100a. The component 100a of FIG. 2 may be equivalent to the component 100 described above with reference to FIG. 1. FIG. 3 is an illustration of a section of a workpiece 106 comprising the local surface 108. A plurality of deposits 110a-c of a viscous medium has been formed on the local surface 108.

[0115] In the example illustrated in FIG. 2, the first surface 102 is curved, information regarding the topography of the first surface 102 may thus comprise information about the curvature of the first surface 102. The local surface 108 of the workpiece 106 in FIG. 3 is flat (not warped), information regarding the topography of the local surface 108 may thus comprise information that the local surface 108 is flat.

[0116] The information regarding the topography of the first surface 102 may further comprise information about the contact pads 104, 104a and their positions. The information regarding the topography of the first surface 102 may for example describe how the first surface differs from a plane P. The information may include a topography map, or measurements of specific positions.

[0117] In FIG. 3, a plurality of deposits 110a-c have been formed on the local surface 108 by application of droplets of viscous medium using non-contact dispensing. The deposits are formed in positions which are to be aligned with the contact pads 104 when the component 100a is mounted on the workpiece 106. Each of the deposits 110a-c has a height h.sub.1, h.sub.2, h.sub.3 which is based on the information regarding the surface topography of the first surface 102. In some embodiments, the heights of the deposits may be based on surface topographies of both the first surface 102 and the local surface 108. In other embodiments, one of the surfaces may be assumed to be flat (planar/non-curved).

[0118] In FIG. 2, the plane P extends from the lowest point of the middle contact pad 104b. Due to the warpage of the component 100a, the outermost contact pads 104a are separated a distance p.sub.1 from the plane P. The height h.sub.1 of the deposits 110a which are positioned to align with the outermost contact pads 104a must therefore be higher than the height h.sub.2 of the center deposit 110b in order to be in contact with contact pad 104a upon mounting of the component 100a on the workpiece 106. In the present example, the center deposit 110b may have been formed by application at least one droplet of the viscous medium using non-contact dispensing. The center deposit 110b may for example have a standard height/volume, or a minimal accepted height/volume. Each of the other deposits 110a, 110c may have been formed by non-contact dispensing of a single droplet having a larger volume adapted to provide a height such that the resulting deposit forms a connection between the workpiece and the respective contact pad. Alternatively, each of the other deposits 110a, 110c may have been formed by non-contact dispensing of more than one droplet, such that the resulting deposit forms a connection between the workpiece and the respective contact pad.

[0119] With reference to FIG. 4, identification of first portions 112 and second portions 114, in accordance with some embodiments, will be described. With reference to FIG. 5, formation of deposits 110a-c on the workpiece 106, in accordance with some embodiments, will be described.

[0120] FIG. 4 is an illustration of a component 100 and a section of a workpiece 106 comprising the local surface 108 onto which the component 100 is to be mounted. The component 100 and the workpiece 106 of FIG. 4 may be equivalent to the component 100, 100a and the workpiece 106, 106a described above with reference to FIGS. 1-3, except in that in this example there are no contact pads 104 on the first surface 102 of the component 100a. It will however be appreciated that the methods described with reference to FIGS. 4 and 5 are applicable for components including contact pads (or other structures) as well.

[0121] FIG. 5 is an illustration of a section of a workpiece 106 comprising the local surface 108. A plurality of deposits 110a-c of a viscous medium has been formed on the local surface 108.

[0122] As in FIGS. 2 and 3, the first surface 102 is curved and the local surface 108 of the workpiece 106 is flat (not warped). When data regarding the surfaces 102, 108 have been obtained, it is possible to predict and analyze a future distance variation between the first surface 102 and the local surface 108 when the component 100 is mounted on the workpiece 106.

[0123] The distance d between the first surface 102 and the local surface 108 varies in FIG. 2. Two first portions 112 have been identified in which the distance is larger than the average distance d.sub.a. A second portion 114 has also been identified, in which the distance is smaller than the average distance d.sub.a.

[0124] In the example illustrated in FIG. 5, a plurality of deposits 110a-c have been formed on the local surface 108. The heights of all deposits 110a-c are not equal. In particular, the deposits 110a formed in the first regions 112 have a height h.sub.1 which is larger than the average height h.sub.a of the deposits 110a-c. the deposit 110b which is formed in the second region 114 has a height h.sub.2 which is smaller than the average height h.sub.a of the deposits 110a-c. The remaining two deposits 110c, which are formed outside of the first regions 112 and the second region 114, have heights coinciding with the average height h.sub.a of the deposits.

[0125] The analysis of the distance may be performed in different ways. As an example, the average distance d.sub.a may be calculated. After this, first portions 112 in which the distance is larger than the average distance d.sub.a may be identified, and (optionally) second portions 114 in which the distance is smaller than the average distance d.sub.a may be identified. Based on this, the step of forming the deposits may be adapted such that (at least some) deposits 110a in the first regions 112 have a height h.sub.1 which is larger than an average height h.sub.a of the plurality of deposits 110a-c. Further, (optionally) at least some deposits 110c formed in second portions 114 may have a height h.sub.2 which is smaller than the average height h.sub.a of the deposits 110a-c.

[0126] Often, the positions of the deposits are predetermined to match contact points of the component 100 and/or the workpiece 106. Thus, as a further example, the distance d at each predetermined position of a deposit (or at least a subset of the predetermined positions of a deposit) may be analyzed. From this analysis, regions 112, 114 in which the distance is larger or smaller than an average may be determined, and the heights of the deposits adapted accordingly. Alternatively, a compensation factor may be calculated for each analyzed position (in other words for each deposit in an analyzed position) based on the analysis of the distance at the position. Thus, each deposit in an analyzed position may receive a height adapted to the specific distance in that position. If both surfaces 102, 108 were perfectly flat, the compensation factor for each analyzed deposit would be 1, since all the deposits would have the same size, and a nominal volume or an initial estimate of volume (and height) based e.g. on the size of the contact points/pad or the distance in between the contact points may be used.

[0127] Information regarding the surface topography of the surfaces 102, 108 may not only comprise information about the current topography of the surfaces. As previously mentioned, the analyzed distance is the distance between the first surface 102 and the local surface 108 upon mounting of the component 100 on the workpiece 106. In certain embodiments, mounting the component may comprise applying energy, for example heat or radiation (such as light), directly to the deposits or to the component and the workpiece, in order to further secure the component in place. Depending on the viscous medium used, light may for example be applied to the deposits in order to cure (harden) the deposits, or heat may be applied to melt/reflow the viscous material of the deposits. The application of energy may induce a further deformation of the component 100, 100a and/or the workpiece 106. This further deformation caused by the energy application often follows certain patterns, meaning that the further deformation may be predicted. The information regarding the surface topography of the surfaces 102, 108 may further comprise information regarding the predicted topography change, so that the heights of the deposits 110a-c may be adapted to compensate the predicted topography change.

[0128] With reference to FIGS. 6a-c, mounting of a component 100a-c onto a local surface 108 of a workpiece 106a-c will be described.

[0129] FIGS. 6a-c are illustrations of a component 100a-c mounted on a local surface 108 of a workpiece 106a-c.

[0130] The component 100a and the workpiece 106a of FIG. 6a may be equivalent to the components 100, 100a and workpieces 106 described above with references to the preceding figures.

[0131] The component 100a has a plurality of contact pads 104 on its first surface 102, like in FIGS. 1 and 2. A plurality of deposits 110 have been formed on the local surface 108 in positions aligned with the positions of the contact pads 104. Like in FIGS. 3 and 5, the heights of the deposits 110 have been adapted based on the surface topographies of the first surface and the second surface, and/or on the variations in distance between the first surface 102 and the local surface 108 caused by the warpage/curvature of the component 100a. Each deposit 110 thus forms a connection (ensures contact) between the workpiece 106 and its respective contact pad 104.

[0132] Placing the component on the workpiece, or mounting the component 100a onto the workpiece, may comprise bringing the component 100a and the workpiece 106c together, and aligning the first surface 102 with the local surface 108. Thus, each contact pads 104 may be aligned with a corresponding deposit 110. The viscous medium of the deposits 110 may keep the component 100 in place.

[0133] FIG. 6b illustrates a component 100b mounted on a local surface 108 of a workpiece 106b. The example shown in FIG. 6b may be equivalent to the example shown in FIG. 6a, except in that the component 100b is not warped/curved while the workpiece 106b is warped/curved, and that the component 100b has no contact pads.

[0134] More specifically, the workpiece 106b is curved such that an end portion 113 of the local surface 108 is curved towards the component 100b. Thus, the distance between the component 100b and the workpiece 106b is smaller in the end portion 113, while the distance is substantially the same for the rest of the local surface 108. The deposit 110b formed in the end portion 113 has a height h.sub.2 based on the topography of the first surface and the local surface 108. The height h.sub.2 of the deposit 110b formed in the end portion 113 is therefore lower than the height h.sub.1 of the other deposits 110a. The height h.sub.2 is smaller than the average height h.sub.a, while the other deposits 110a have the same height h.sub.1 which is larger than the average height h.sub.a.

[0135] FIG. 6c illustrates a warped/curved component 100c mounted on a local surface 108 of a curved/warped workpiece 106c. A plurality of deposits 110 has been formed on the first surface 102 of the component 100c before mounting of the component 100c on the workpiece 106c. Each of the deposits 110 has an individual height based on (adapted to) the topographies of the first surface and the local surface and/or based on the distance between the first surface 102 and the local surface 108 at the position at which the individual deposit is formed.

[0136] In other embodiments, deposits may be formed on both the first surface and the local surface before mounting. The deposits may be formed in corresponding positions on the surfaces, such that they line up upon mounting of the component on the workpiece. Alternatively, the deposits may be formed in complementary positions.

[0137] With reference to FIG. 7, further steps of mounting a component 100 on a workpiece 100 will be described.

[0138] FIG. 7 shows the same example as illustrated in FIG. 6a, except in this figure, the contact pads 104 have partially sunk into the deposits 110. The viscous material of the deposits 110 may allow that the deposits 110 become deformed after initial placement/mounting of the component 100a. For example, the deformation may take place due to gravity acting on the component 100a, or to an external force applied on the component 100a and/or the workpiece 106a during mounting of the component 100a. In some embodiments, after bringing the component 100a and the workpiece 106a together to form an assembly, heat, light, or other form of energy may be applied to the assembly (comprising the component 100a and the workpiece 106a).

[0139] In some embodiments, a controlled application of heat may cause the deposits 110 to reflow, or melt. Such a decrease in viscosity (caused by the application of heat) may allow a larger contact surface between the deposits and the contact pads 104 or points on the component 100a and the workpiece 106a. This decrease in viscosity may for example cause partial sinking of the contact pads into the deposits, as shown in FIG. 7. When the viscous material cools, it may harden to form more robust joints.

[0140] For example, in embodiments comprising electronic components and in which the viscous medium comprises solder paste, a controlled application of heat, light or other form of energy may cause the solder paste to reflow and form permanent solder joints

[0141] Alternatively, a controlled application of light or other form of energy may be performed to cure (harden) the viscous material of the deposits 110, thereby securing the component 100, 100a to the workpiece 106.

[0142] With reference to FIGS. 8 and 9, a system 220, in accordance with some embodiments, will be described.

[0143] FIG. 8 is a block diagram of a (depositing) system 220 for depositing a viscous medium. The depositing system 220 comprises a non-contact dispensing (depositing) device 222, which is arranged for depositing a viscous medium onto a surface, such as a first surface 102 of a component 100 or a local surface 108 of a workpiece 106, as described above with reference to FIGS. 1-7.

[0144] FIG. 9 is a schematic illustration of parts of a system 220 for depositing a viscous medium, illustrated during the deposition of a viscous medium onto a workpiece 106.

[0145] The depositing system further comprises a control unit 224. The control unit 224 may be internal to the non-contact dispensing 220. In other embodiments, the control unit 224 may be an external control unit, such as a processor, computer etc., in communicative contact with the non-contact dispensing 220.

[0146] The control unit 224 is configured to obtain information about surface topographies of a first surface of a component to be mounted on the workpiece and/or a local surface of the workpiece 106 on which the component is to be mounted. This information may for example be retrieved from a storage unit 226 in communicative contact with the control unit 224.

[0147] Alternatively, the depositing system may be configured to perform measurements of the first and/or local surface using measurement device 230.

[0148] The control unit 224 may further be adapted to use the obtained information to analyze how the surface topographies will affect the distance between the first surface of the component and the local surface of the workpiece 106. For example, this analysis may be performed as described above with reference to the preceding figures.

[0149] For example, the control unit 224 may be adapted to identify at least one first portion (such as first portion 112 in FIGS. 4 and 5) of the first or local surface in which the distance between these surfaces upon mounting will be larger than an average distance between the first surface and the local surface.

[0150] The control unit 224 is further adapted to determine heights of the deposits 110 to be formed on the workpiece 106 based on the information regarding surface topography. Heights of the deposits may be adapted to the predicted distance between the first surface and the local surface upon mounting. A deposit formed in a first portion, where the distance will be larger than the average distance, may thus have a height/volume larger than an average height/volume of the plurality of deposits.

[0151] The control unit 224 is further configured to cause the non-contact dispensing device 222 to form each of the deposits of viscous medium by applying ay least one droplet of the viscous medium onto the local surface of the workpiece 110 or the first surface of the component, using non-contact dispensing. For example, the control unit may send instructions to a non-contact dispensing device controller (not depicted) which may control operation of the non-contact dispensing device 222. Alternatively, the control unit 224 may directly control operation of the non-contact dispensing device 222. The system 220 may comprise a second depositing device 228. The second depositing device may be configured to deposit a plurality of deposits of medium of a substantially same height viscous onto a first surface of a component or a local surface of a workpiece. The non-contact dispensing 222 may then be configured to adapt a height of at least one of the plurality of deposits, e.g. by applying additional viscous medium to a deposit and/or by removing viscous medium from a deposit.

[0152] FIG. 9 shows an example of a non-contact dispensing device 222 arranged for applying droplets 234 of a viscous medium 232 onto a local surface 108 of a workpiece 106. The workpiece 106 may be equivalent to the workpiece 106a, illustrated in FIGS. 3, 5 and 6, adapted to receive the curved component 100a.

[0153] In the illustrated example, the non-contact dispensing device 222 is a jetting device, illustrated by a jetting nozzle comprising a volume of viscous medium 232. The jetting device 222 is shooting (jetting) individual droplets 234 onto the local surface 108 to build a deposit 110b. In this example, a plurality of droplets is applied to form the deposit 110b. In other embodiments, the size/volume of each individual jetted droplet may be adapted such that only one droplet is used to form each deposit 110a-c.

[0154] The jetting head has, prior to the illustrated moment, travelled over the workpiece 106, and formed a first deposit 110a having a first height h.sub.1, and a second deposit 110c having a second lower height h.sub.3.

[0155] The system 220 further comprises a measurement device 230, which is arranged and configured to perform measurements of the local surface 108. For example, the measurement device 230 may travel, e.g. together with the jetting head 222, over the local surface 108, performing measurements of the surface. In the illustrated example, the measurement device 230 is measuring a distance to the second deposit 110c. Repeated measurements may be used to determine a (new, updated) surface topography of the surface, and/or to measure the actual heights of the deposits 110a, 110c. Based on measurements made by the measurement device 230, further viscous medium may be applied, by the non-contact dispensing device 222, to one or more deposits 110a-c.

[0156] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0157] For example, the plurality of deposits may be formed on both the first surface of the component and on the local surface of the workpiece.

[0158] Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements.

[0159] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.