Carrier for holding electronic components during visual inspection, visual inspection device and inspection method

Abstract

The present invention relates to a carrier for holding electronic components during visual inspection, comprising: a base structure holding suction cups with gripping outer ends for gripping and holding electronic components, which suction cups are attached to the base structure on their opposite base outer ends. Also is provided a background structure at least partially covering the sides of the suction cups. The invention also relates to a visual inspection device comprising such a carrier and an optical camera directed towards the carrier as well as a method for visual inspection of electronic components.

Description

[0001] Carrier for holding electronic components during visual inspection, visual inspection device and inspection method

[0002] The present invention relates to a carrier for holding electronic components during visual inspection, having a base structure carrying at least one suction cup with a gripping outer end defining a contact surface for gripping and holding an electronic component. The invention also relates to a visual inspection device comprising such a carrier and to method for visual inspection of electronic components.

[0003] Electronic components are used on a huge scale and can for instance be formed by diodes (for example, light emitting diodes or LEDs), transistors, integrated circuits (IC / chips), chip-based sensors for detecting force, pressure, fingerprint, light and images, and chip-based actuators (MEMS; microelectromechanical systems) and / or other types of passive or active electronic components.

[0004] During the process of manufacturing electronic components, the components are usually manufactured in larger units (assemblies) of joined electronic components which units subsequently are divided into smaller units of one or several individual electronic components. Typically the electronic components are initially mounted on a carrier, also referred to as a substrate, for instance formed by, but not limited to, a wafer, a lead frame, or a (printed circuit) board. The subsequent dividing of the electronic components in smaller or individual units is also referred to as separating, singulating or individualizing the electronic components. The separation into smaller units of for instance individualised electronic components may be realized by means of various types of machining processes, such as sawing, punching, liquid cutting and / or laser cutting. After separating all the electronic components from a complete carrier the electronic components may be sorted by a sorter; differentiating selected (e.g. ejecting rejected) components from other (e.g. approved) components. The individualised electronic components may then be further processed.

[0005] As the electronic components undergo a continuous reduction of scale, the production requirements set for the precision of the electronic components are also becoming stricter. The difficulty in meeting these strict requirements lies amongst others in being able to arrange packages with a precision and accuracy which only differ from the desired specifications on micron level (pm) in respect of form. Furthermore a visual control of the dimensional and functional accuracy is of importance as the electronic components must often fit future installation situations, also situations for instance wherein the sides of the electronic component must remain clear of pollutions like for instance encapsulating material for arranging electronic connections, heat exchange and / or as sensor surface.

[0006] As thus the conditions of, especially the sides of, the electronic components must be accurately dimensioned during the production of the electronic components the individual electronic components are normally subjected to a visual inspection whereby the electronic components during visual inspection are held - on a certain distance of each other - by a carrier allowing visual access to the sides of the individual electronic components. Normally the electronic components are held by a carrier comprising a base structure carrying at least one, but preferably plural, suction cups, each cup having a gripping outer end defining a contact surface for gripping and holding an individual electronic component enabling a visual inspection of - amongst others - the sides of the electronic components.

[0007] The present invention has for its object to provide alternative means and methods to enhance the quality and accuracy of the visual inspection of electronic components.

[0008] Therefore the present invention provides a carrier for holding electronic components during visual inspection, comprising: a base structure; at least one suction cup including a gripping outer end defining a contact surface for gripping and holding an electronic component, an opposite base outer end attached to the base structure, and at least one channel extending between the gripping outer end and the base outer end; and a background structure for the at least one suction cup with a visible surface parallel to the contact surface of the suction cup, wherein the cross-sectional area of the suction cup at the contact surface is smaller than a, parallel to the contact surface, cross sectional area at distance of the contact surface; and wherein the visible surface of the background structure is optionally allocated between the contact surface of the suction cup and the base outer end of the suction cup and an opening in the visible surface of the background structure surrounds the at least one suction cup whereby the opening in the visible surface of the background structure is smaller than broader part of the suction cup at the opposite base outer end. With such a carrier a least a substantial (widening) part of the suction cup(s) is visually covered for inspection by the background structure as the background structure surrounds the suction cup(s) at an height / position such that a widening part of the suction cup(s) is hidden from view. The reason for the design of the suction cups, with a gripping smaller outer end contact surface and an opposite wider base outer end, is that the electronic components become increasingly smaller and that the suctions cups made of a flexible material (for a desired grip on the electronic components normally an elastomer / rubber is used) require a minimal stability. In case the suction cups would have a uniform cross- sectional area over their complete length that would correspond to the (relative small) contact surface the suction cups would lack a required shape stability. To overcome this problem the suction cups as often used are shaped with the wider cross sectional area at distance of the contact surface. The channel extending between the gripping outer end and the base outer end of the suction cups is for passing through a lower pressure to the contact surface and for the removal of the lower pressure afterwards. The functional side of the background structure is the visible side of the background structure being the side faced away from the base structure. It is important that the wider part of the suction cups is visually shielding the suction cups to realise the desired effect that during the inspection not the sides of the suctions cups is disturbing the visual inspection. The colour of the suction cups is difficult to change due to the mechanical properties desired while the colour of the backgrounds structure is less (or not) limited due to other functional demands which provides the advantage of having the possibility of influencing the (visual) contrast between the electronic components to be inspected and the visual background formed by the background structure. A higher contrast will enhance the quality of the visual inspection. A further advantage of the background structure according to the present invention is that due to the (higher) position of the background structure the electronic components to be inspected and the background structure are relative close to each other and are therefore close to the focal point of the inspection means (camera). This will also be supportive in enhancing the quality of the electronic components visual inspection.

[0009] It is also possible that the visible surface of the background structure is allocated between the contact surface of the suction cup and the base structure, in particular a side of the base structure facing towards the contact surface of the suction cup. This allows to further reduce the size, in particular the height, of the carrier, which is particularly beneficial in the field of processing electronic components, such as semiconductor products.

[0010] Optionally the base structure and the background structure are combined as one but the base structure and the background structure may also be two individual components.

[0011] The - normally flexible - suction cups may be detachable attached to the base structure as this allows to exchange the relative to the base structure more vulnerable suction cups after a period of use. The shape of the suction cups may vary but with an effective shape that is also easy to clean the suction cups may over at least a part of their length be tapered.

[0012] For realising that the sidewall of the suction cups is not negatively influencing the visual inspection it is desired that a least a part of the sidewalls between the contact surfaces and the base outer ends of the suctions cup is covered by the background structure. On the other hand for a good grip of the suction cups on the electronic components it is desired that the suction cups partially protrude from the visible surface of the background structure.

[0013] In a further advantageous embodiment the visible surface of the background structure is substantially flat providing an even image over a larger surface. While for an optimal visual effect at least part of the background structure may have a colour that differs from the colour of the (side of the) suction cup, preferably a colour contrasting with the colour of the suction cups. In practise a blue colour for the visible side of the background structure has led to favourable results. Yet in a specific embodiment at least part of the background structure may be illuminable or the colour may be regulated, also this additional technical feature will make it easier to visually distinguish between the electronic components and the background. Varying the colour of the visible surface of the background structure may be realised by using an electrifying a frequency sensitive material. And to even further enhance the visual distinguishment the background structure may emit a polarized light. The background structure may comprises an electrostatic discharge safe (EDS) material. The use of such material enables to prevent or at least to limit the occurrence of electrostatic discharge, which could lead to damaging the electronic components but which may also lead to lesser quality of the visual inspection.

[0014] For simplifying maintenance, cleaning and / or replacement of carrier the background structure may be detachable attached to the base structure. With this embodiment the background may also be replaced, when for instance a differently coloured background is required. This is further beneficial as the background structure may be replaced without requiring the need to also replace one or more of the suction cups. The visible surface of the background structure is typically at a distance of the base structure. This provides space between said visible surface and the base structure, in which space couplings can be provided to detachably couple the background structure to the base structure.

[0015] As for a good grip on the electronic components but also providing substantial structural stability the contact surface of the suction cup may protrudes [0,0 - 10] mm, preferably [0,1 - 2.5] mm, more preferably [0,1 - 0.5] mm, most preferably [0,1 - 0.3] mm, from the visible surface of the background structure ranges. Preferably a carrier comprises a plurality of suction cups, preferably with a distance between closest suction cups, from center point to center point of [1 - 250] mm, preferably [2.5 - 100] mm, more preferably [5 - 50] mm. Typically, the visible surface of the background structure is wider than the distance between adjacent suction cups. Such a background structure can optimally achieve its desired effect to enhance visual inspection by covering said distance between the suction cups.

[0016] A further advantageous embodiment also enables to vary the mutual distance of the suction cups by a displacement drive. This not only allows visual inspection but also makes is possible to simultaneously change the pitch between the plural electronic components, e.g. to fit the demands of a subsequent processing step.

[0017] The background structure may be embodied as a single structure but alternatively the individual suction cups may be provided with individual background structures. The present invention also provides comprising a carrier according to the present invention and at least one optical camera directed towards the at least one suction cup for inspecting at least one electronic component held by the carrier. The carrier and the optical camera may be built together on a mutual frame. With such a visual inspection device the advantages as listed above in reference to the carrier according to the present invention may be realised as well, these advantages are here included by reference in relation to the visual inspection device according to the present invention.

[0018] The invention also provides a method for visual inspection of electronic components with a visual inspection device according to the present invention comprising the method steps: attaching at least one electronic component to the suction cup of the carrier, visual inspecting the at least one electronic component held by the carrier, and processing the perceived images whereby a distinction is made between the electronic component and the background structure. With this method the quality of visual inspection will be enhanced as explained in relation to the carrier according to the present invention, which advantages are also here incorporated by reference. In an advantageous embodiment of the present visual inspection method for an enhanced contrast during inspection the colour of the background structure may changed to a colour that is different from the colour(s) of the electronic component to be visual inspected. An even more preferable the colour of the background may actively changed dependent on the inspection results of prior inspection cycles, thus resulting in a feed-back process control..

[0019] The present invention will be further elucidated on the basis of the non-limitative exemplary embodiments shown in the following figures. Herein shows: figure 1 a perspective view on a visual inspection device comprising a carrier and an optical camera directed towards the carrier; figure 2 a cross-section through a part of a carrier according to the present invention; and figure 3 a cross-section through a part of the carrier shown in figure 2 holding electronic components to be inspected. Figure 1 shows a carrier 1 for electronic components and a visual camera 2 directed towards suction cups 3 that are dimensioned for holding electronic components to be inspected by the camera 2. The carrier 1 has a base structure 4 that holds the suctions cups 3 so that an underpressure may be guided to contact surfaces 5 of the suction cups 3.

[0020] In figure 2 a cross-section through a part of a carrier 11 is shown of which base structure 14 detachable hold flexible suction cups 13 that are pushed on protrusions 16 that are part of the base structure 14. The suction cups 13 have on one gripping outer end 17 side contact surfaces 15 for contacting the electronic components to be held (see figure 3) and on the opposite side the suction cups 13 have base outer ends 18 (the base outer ends 18 are pushed over the protrusions 16). Through the suction cups 13 run channels 19 for providing and raising an underpressure at the gripping outer ends 17. Clearly visible is that the cross-section of the suction cups 13 at the gripping outer ends 17, ending in the contact surfaces 15, is smaller than the cross-section of the suction cups 13 at the base outer ends 18.

[0021] Between the suction cups 13 an background structure 20 is proved that has a visible surface 21 that is positioned between the contact surfaces 15 of the suction cups 13 and the base outer ends 18 of the suction cups 13. In the background structure 20 (here embodied as a plate) are openings 22 that surround the suction cups 13 such that the openings 22 in the visible surface 21 of the background structure 20 are smaller than the wider base outer ends 18 of the suction cups 13. The visible surface 21 of the background structure 20 is parallel with the contact surfaces 15 of the suction cups 13. Also visible in this figure 2 is that the background structure 20 is with couplings 23 detachably coupled to the base structure 14.

[0022] Figure 3 shows the cross-section through the part of a carrier 11 as also illustrated in figure 2 but now in the situation that the carriers 11 holds electronic components 24. In the channels 19 running through the suction cups 13 there will be an underpressure now. A camera 25 looking to the sides 26 of the electronic components 25 will now have a background that is provided by the visible surface 21 of the background structure 20 in stead of the side of the suction cups 13. This makes a visual inspection by the camera 25 more reliable then when the background structure 20 was lacking.

Claims

Claims1 . Carrier for holding electronic components during visual inspection, comprising:- a base structure;- at least one suction cup including a gripping outer end defining a contact surface for gripping and holding an electronic component, an opposite base outer end attached to the base structure, and at least one channel extending between the gripping outer end and the base outer end; and- a background structure for the at least one suction cup with a visible surface parallel to the contact surface of the suction cup; wherein the cross-sectional area of the suction cup at the contact surface is smaller than a, parallel to the contact surface, cross sectional area at distance of the contact surface; and wherein the visible surface of the background structure is allocated between the contact surface of the suction cup and the base outer end of the suction cup and an opening in the visible surface of the background structure surrounds the at least one suction cup whereby the opening in the visible surface of the background structure is smaller than broader part of the suction cup at the opposite base outer end.

2. Carrier according to claim 1 , characterized in that the at least one suction cup is detachable attached to the base structure.

3. Carrier according to claim 1 or 2, characterized in that the at least one suction cup over at least a part of its length is tapered.

4. Carrier according any of the preceding claims, characterized in that a part of the sidewall between the contact surface and the base outer end of the at least on suction cup is covered by the background structure.

5. Carrier according to any of the preceding claims, characterized in that the at least one suction cup partially protrudes from the visible surface of the background structure.

6. Carrier according to any of the preceding claims, characterized in that the visible surface of the background structure is substantially flat.

7. Carrier according to any of the preceding claims, characterized in that at least part of the background structure is illuminable, preferably the background structure emits a polarized light.

8. Carrier according to any of the preceding claims, characterized in that the colour of the visible surface of the background structure is variable, for instance by electrifying a frequency sensitive material.

9. Carrier according to any of the preceding claims, characterized in that the background structure is detachable attached to the base structure.

10. Carrier according to any of the preceding claims, characterized in that the contact surface of the suction cup protrudes [0,0 - 10] mm, preferably [0,1 - 2.5] mm, more preferably [0,1 - 0.5] mm, most preferably [0,1 - 0.3] mm, from the visible surface of the background structure ranges.11 . Carrier according to any of the preceding claims, characterized in that the carrier comprises a plurality of suction cups, preferably with a distance between closest suction cups, from center point to center point, is [1 - 250] mm, preferably [2.5 - 100] mm, more preferably [5 - 50] mm.

12. Carrier according to 11 , characterized in that suction cups are mutually displaceable by displacement drive.

13. Carrier according to claim 11 or 12, characterized in that individual suction cups are provided with individual background structures.

14. Visual inspection device comprising a carrier according to any of the claims 1 - 13 and at least one optical camera directed towards the at least one suction cup for inspecting at least one electronic component held by the carrier.

15. Method for visual inspection of electronic components with a visual inspection device according to claim 14, comprising the method steps attaching at least one electronic component to the suction cup of the carrier, visual inspecting the at least one electronic component held by the carrier, and processing the perceived images whereby a distinction is made between the electronic component and the background structure.

16. Inspection method according to claim 15, using a carrier according to any of the claims 1 - 13, whereby the colour of the background structure is changed to a colour that is different from the colour(s) of the electronic component to be visual inspected.

17. Inspection method according to claim 16, whereby the colour of the background is actively changed dependent on the inspection results of prior inspection cycles.

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