Limiting jig for QFN (Quad Flat No-lead) post-baking
By designing a limiting jig for QFN post-baking and using a combination of grooves and positioning pins, the problems of warping and uneven thickness of QFN products during the baking process were solved, stable pressing of the substrate was achieved, wear was reduced, and glue contamination was avoided.
Patent Information
- Application Number
- CN202422398833.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2034-09-30
AI Technical Summary
In the existing technology, QFN products are prone to warping and uneven thickness during the baking process, especially for special products with lids, and traditional pressing methods cannot meet their pressing requirements.
A limiting fixture for QFN post-baking was designed, including a pressing block, a cover plate and a pressing head. The pressing block is provided with a groove and a positioning pin. The depth of the groove is equal to the thickness of the substrate. The positioning pin is used to fix the substrate. The cover plate is provided with a clearance hole, which is positioned by a guide post to ensure the stability and uniform pressing of the substrate.
It effectively avoids the uneven thickness of the substrate during the baking process, reduces the wear caused by substrate slippage, and prevents the glue squeezed out of the hollow cover from contaminating the cover. The operation is light and convenient.
Smart Images
Figure CN223347758U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to integrated circuit board processing technology, and in particular to a limiting fixture for QFN post-baking. Background Art
[0002] Post-baking of the integrated circuit QFN (Quad Flat No-lead Package) is a necessary process after QFN molding. Post-baking generally has two functions. On the one hand, the thermosetting resin fully cross-links at high temperature, so that the resin completes chemical cross-linking. On the other hand, since the QFN is a large-area plastic-encapsulated resin body before being divided, in the case of large areas, due to the inclusion of other materials in the package body, simply performing high-temperature cross-linking without restriction will cause severe warping of the plastic package body, which will have a serious impact on the next printing and cutting processes.
[0003] In order to reduce the degree of warping of the plastic-encapsulated body, the QFN substrate after plastic encapsulation is usually pressed together with a flat steel pressing block and a pressing head under high-temperature baking. This pressing method is simple and effective and can minimize the warping and deformation of the QFN product.
[0004] However, for some special products, such as those requiring lids, the substrate is first plastic-encapsulated and then pre-cut to a certain depth. After pre-cutting, the required lid is applied with glue and then placed directly on the pre-molded substrate, which has been bonded and pre-molded. A pressing plate and a pressing block are then placed and baked. Traditional flat pressing plates and pressing blocks can result in uneven thickness after pressing and baking, and are therefore unable to meet the pressing requirements of pre-cut, glued, and lid-applied QFN products. Utility Model Content
[0005] In order to overcome the above-mentioned defects, the present application provides a limiting fixture for QFN post-baking, which is lightweight and easy to operate. It uses a sunken groove to place the substrate, effectively avoiding the occurrence of uneven thickness of the substrate during the baking process.
[0006] The technical solution adopted by this application to solve its technical problems is:
[0007] A limiting jig for QFN post-baking includes a pressing block, a cover plate and a pressing head. The pressing block includes a front side and a back side arranged opposite to each other, a first clearance hole is provided on the front side, and a groove is provided on the back side. The groove is used to place a substrate, and the depth of the groove is equal to the thickness of the substrate. A hollow cover is fixedly pressed on the substrate, and a pin hole is provided on the substrate. A positioning pin is fixedly installed in the groove. The positioning pin passes through the pin hole and is inserted into the first clearance hole. The cover plate is covered on the back side, and the pressing head is pressed on the cover plate.
[0008] Optionally, a plurality of the pressing blocks are stacked on each other, and the cover plate is pressed onto the pressing block on the top layer. The cover plate is provided with a second clearance hole, and the positioning pin is inserted into the second clearance hole.
[0009] Optionally, the first clearance hole and the second clearance hole are both blind holes.
[0010] Optionally, the pressure block, the cover plate and the pressure head are positioned by guide pillars, a first guide pillar hole is opened on the pressure block, a second guide pillar hole is opened on the cover plate, and a third guide pillar hole is opened on the pressure head, and the guide pillars are sequentially inserted into the first guide pillar hole, the second guide pillar hole and the third guide pillar hole.
[0011] Optionally, the first guide post hole, the second guide post hole and the third guide post hole are all through holes.
[0012] Optionally, a notch is provided on the edge of the pressing block, the notch is located in the groove, and a plurality of parallel arranged clearance grooves are provided on the cover plate.
[0013] Optionally, the clearance groove is along the width direction of the cover plate, and the clearance groove runs through the entire width direction of the cover plate.
[0014] Optionally, a fixing groove is provided in the groove, and the positioning pin is fixedly installed in the fixing groove.
[0015] Optionally, the pressing block is an aluminum alloy pressing block, and the weight of the pressing head is 4-8 kg.
[0016] The beneficial effects of the present application are as follows: in the present application, a groove is provided on the pressing block, and the depth of the groove is designed to be equal to the thickness of the QFN substrate. The substrate is stored in the groove, which can solve the problem of uneven thickness of the substrate of the hollow cover after baking; considering the uniformity of the substrate pressing, in order to avoid displacement of the substrate when placed, a positioning pin is provided on the pressing block, and the substrate is fixed by the positioning pin, and a clearance hole is provided on the pressing block and the cover plate to accommodate the positioning pin. The jig is light and easy to operate. The substrate is placed in a sunken groove, which effectively avoids the uneven thickness of the substrate during the baking process. After pressing, neither the substrate nor the pressing block will move, reducing the wear on the substrate caused by slippage, and also preventing the glue squeezed out of the hollow cover from contaminating the cover plate. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a schematic diagram of the structure of the limiting fixture in this application;
[0018] Figure 2 This is one of the exploded views of the limiting fixture in this application;
[0019] Figure 3 This is the second exploded view of the limiting fixture in this application;
[0020] Figure 4 This is one of the structural diagrams of the briquette in this application;
[0021] Figure 5 This is the second structural diagram of the briquette in this application;
[0022] Figure 6 This is a schematic diagram of the structure of the cover plate in this application;
[0023] Figure 7 Schematic diagram of the structure of the substrate in this application;
[0024] In the figure: 10-pressing block, 11-front side, 12-back side, 13-groove, 14-locating pin, 15-first clearance hole, 16-first guide post hole, 17-notch, 20-guide post, 30-cover plate, 31-clearance groove, 32-second guide post hole, 33-second clearance hole, 40-pressing head, 41-third guide post hole, 50-base plate, 51-hollow cover, 52-pin hole. DETAILED DESCRIPTION
[0025] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described in this application are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the following drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the objects used in this way can be interchanged where appropriate so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0027] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.
[0028] Example: Figure 1-7 As shown, a limiting fixture for QFN post-baking includes a pressing block 10, a cover plate 30 and a pressing head 40. The pressing block 10 includes a front side 11 and a back side 12 arranged opposite to each other. A first clearance hole 15 is provided on the front side 11, and a groove 13 is provided on the back side 12. The groove 13 is used to place a substrate 50. The depth of the groove 13 is equal to the thickness of the substrate 50. A hollow cover 51 is fixedly pressed on the substrate 50, and a pin hole 52 is provided on the substrate 50. A positioning pin 14 is fixedly installed in the groove 13. The positioning pin 14 passes through the pin hole 52 and is inserted into the first clearance hole 15. The cover plate 30 covers the back side 12, and the pressing head 40 is pressed on the cover plate 30.
[0029] like Figure 1-3As shown, multiple pressing blocks 10 are stacked on each other, and the cover plate 30 is pressed onto the pressing block 10 on the top layer. The cover plate 30 is provided with a second clearance hole 33, and the positioning pin 14 is inserted into the second clearance hole 33. During operation, the substrate 50 is placed into the groove 13 of the pressing block 10. During the placement process, the positioning pin 14 is used to pass through the pin hole 52 on the substrate 50. Then, multiple pressing blocks 10 are stacked on each other, and the positioning pin 14 on the lower pressing block 10 is inserted into the first clearance hole 15 of the upper pressing block 10. The reverse side 12 of the pressing block 10 faces upward, and the cover plate 30 is pressed onto the pressing block 10 on the top layer. Finally, the pressing head 40 is pressed on the cover plate 30, and the positioning pin 14 on the pressing block 10 on the top layer is inserted into the second clearance hole 33 of the cover plate 30. In the present application, a groove 13 is opened on the pressing block 10, and the depth of the groove 13 is designed to be equal to the thickness of the QFN substrate 50. The substrate 50 is stored in the groove 13, which can solve the problem of uneven thickness of the substrate of the hollow cover after baking; considering the uniformity of the substrate pressing, in order to avoid displacement of the substrate when it is placed, a positioning pin 14 is set on the pressing block 10, and the positioning pin 14 is used to fix the substrate, and a clearance hole is opened on the pressing block 10 and the cover plate 30 to accommodate the positioning pin 14.
[0030] like Figure 5 and Figure 6 As shown, the first clearance hole 15 and the second clearance hole 33 are both blind holes. The depth of the first clearance hole 15 and the second clearance hole 33 is greater than the height of the positioning pin 14 protruding from the pressing block 10, so that the front surface 11 of the pressing block 10 and the cover plate 30 can avoid the positioning pin 14.
[0031] like Figure 1-3 and Figure 5-6 As shown, the pressing block 10, the cover plate 30 and the pressing head 40 are positioned by the guide pillar 20, the pressing block 10 is provided with a first guide pillar hole 16, the cover plate 30 is provided with a second guide pillar hole 32, and the pressing head 40 is provided with a third guide pillar hole 41, and the guide pillar 20 is sequentially inserted into the first guide pillar hole 16, the second guide pillar hole 32 and the third guide pillar hole 41.
[0032] The first guide post hole 16, the second guide post hole 32, and the third guide post hole 41 are all through holes. The guide post 20 is used to align the pressing block 10, the cover plate 30, and the pressing head 40, ensuring that they are in a straight line when the substrate is pressed down, preventing the pressing block 10 from moving during operation, and thus ensuring that the substrate 50 will not be damaged by sliding.
[0033] like Figure 4-7 As shown, a notch 17 is provided on the edge of the pressing block 10 , and the notch 17 is located in the groove 13 . A plurality of parallelly arranged clearance grooves 31 are provided on the cover plate 30 .
[0034] The clearance groove 31 runs along the width of the cover plate 30 and extends through the entire width of the cover plate 30. Slots are provided on both sides of the pressing block 10 to facilitate product placement and save time. The clearance groove 31 is provided on the cover plate 30 so that when the pressing head 40 is placed, glue squeezed out of the hollow cover 51 due to the impact force can flow out through the clearance groove 31, thereby preventing contamination of the cover plate 30.
[0035] The groove 13 is provided with a fixing groove, and the positioning pin 14 is fixedly installed in the fixing groove. Optionally, four fixing grooves are provided on the groove 13, and a positioning pin 14 is installed in each fixing groove. The four positioning pins 14 are used to position the substrate 50, thereby improving the stability of the substrate 50.
[0036] The pressing block 10 is an aluminum alloy pressing block, and the pressing head 40 weighs 4-8 kg. The pressing block 10 is made of aluminum alloy material and a hardening process. The thickness of the pressing block 10 is about 20 mm, so the pressing block 10 is light and easy to handle. The fixture is lightweight and easy to operate. The substrate is placed in a sunken groove, which effectively avoids uneven thickness of the substrate during the baking process. After pressing, neither the substrate nor the pressing block will move, reducing wear on the substrate due to slippage. It also prevents glue squeezed out of the hollow cover from contaminating the cover plate.
[0037] It should be noted that those skilled in the art may make a number of modifications and improvements without departing from the concept of this application, and these modifications and improvements are all within the scope of protection of this application. Therefore, the scope of protection of this patent application shall be based on the appended claims.
Claims
1. A QFN post-baking limiting fixture, characterized by: The invention comprises a pressing block (10), a cover plate (30) and a pressing head (40), wherein the pressing block (10) comprises a front side (11) and a back side (12) arranged opposite to each other, a first clearance hole (15) is provided on the front side (11), a groove (13) is provided on the back side (12), a substrate (50) is placed in the groove (13), the depth of the groove (13) is equal to the thickness of the substrate (50), a hollow cover (51) is fixedly pressed on the substrate (50), a pin hole (52) is provided on the substrate (50), a positioning pin (14) is fixedly installed in the groove (13), the positioning pin (14) passes through the pin hole (52), and the positioning pin (14) is inserted into the first clearance hole (15), the cover plate (30) covers the back side (12), and the pressing head (40) is pressed on the cover plate (30).
2. The QFN post-baking limiting fixture according to claim 1, characterized in that: The plurality of pressing blocks (10) are stacked on each other, and the cover plate (30) is pressed onto the uppermost pressing block (10). The cover plate (30) is provided with a second clearance hole (33), and the positioning pin (14) is inserted into the second clearance hole (33).
3. The QFN post-baking limiting fixture according to claim 2, characterized in that: The first clearance hole (15) and the second clearance hole (33) are both blind holes.
4. The QFN post-baking limiting fixture according to claim 1, characterized in that: The pressing block (10), the cover plate (30) and the pressing head (40) are positioned by means of a guide post (20); a first guide post hole (16) is provided on the pressing block (10), a second guide post hole (32) is provided on the cover plate (30), and a third guide post hole (41) is provided on the pressing head (40); and the guide post (20) is sequentially inserted into the first guide post hole (16), the second guide post hole (32) and the third guide post hole (41).
5. The QFN post-baking limiting fixture according to claim 4, characterized in that: The first guide post hole (16), the second guide post hole (32) and the third guide post hole (41) are all through holes.
6. The QFN post-baking limiting fixture according to claim 1, characterized in that: A notch (17) is provided on the edge of the pressing block (10), and the notch (17) is located in the groove (13). A plurality of parallel arranged clearance grooves (31) are provided on the cover plate (30).
7. The QFN post-baking limiting fixture according to claim 6, characterized in that: The paving groove (31) is along the width direction of the cover plate (30), and the paving groove (31) runs through the entire width direction of the cover plate (30).
8. The QFN post-baking limiting fixture according to claim 1, characterized in that: A fixing groove is provided in the groove (13), and the positioning pin (14) is fixedly installed in the fixing groove.
9. The QFN post-baking limiting jig according to claim 1, characterized in that: The pressing block (10) is an aluminum alloy pressing block, and the weight of the pressing head (40) is 4-8 kg.