A method and fixture for tinning a single QFN frame product.

Abstract

This invention discloses a method and fixture for tinning a single QFN frame product. The method includes fixing the single QFN frame product onto the fixture's clamp for tinning; removing the fixture for cleaning after tinning; and then observing the product. By fixing the single QFN frame product onto the clamp, each pin of the single QFN frame product is made conductive. Then, the assembled fixture is installed in the tinning tank, simulating the state of the entire product line in the tinning tank, ultimately completing the tinning process for the single product. This solves the problem of non-conductive pins after the product is cut into individual pieces, preventing tinning and electroplating. It perfectly simulates the pin connectivity state of the QFN frame product before it is cut into individual pieces, thus achieving a normal tinning process. The tin layer effect after the process is consistent with the appearance and thickness of the entire tin-plated product line, meeting the product tinning process requirements and effectively improving the production line yield and product reliability.

Description

Technical Field

[0001] This invention relates to the field of packaging technology, specifically to a method and fixture for tinning a single QFN frame product. Background Technology

[0002] Currently, after some high-value QFN products are cut into individual finished products, it has been found that the appearance of the tin layer of some finished products is abnormal, resulting in a low yield rate. At present, there is no effective way to solve the yield loss caused by the abnormal appearance of finished products. Summary of the Invention

[0003] This invention provides a method and fixture for tinning a single QFN frame product, with the aim of solving the aforementioned problems in the background art.

[0004] The technical solution provided by this invention is as follows:

[0005] The first aspect of this invention provides a method for tinning a single QFN frame-type product, comprising the following steps:

[0006] A fixture is provided, and the cut single target products are loaded into the fixture. Each fixture contains 2n target products. After loading, the fixture is placed in the tin plating tank of the tin plating equipment for tin plating operation.

[0007] After tinning is completed, the fixture is removed and transferred to the cleaning tank of the tinning equipment to remove residual chemicals;

[0008] After cleaning, the fixture is removed, and the tin-plated target product is taken out of the fixture. The tin plating of each pin of the target product is observed and confirmed. Once it is confirmed that there are no errors, the tin plating process of a single target product is completed.

[0009] Where n is a positive integer ≥ 1, and the target product is a QFN framework product.

[0010] Furthermore, before placing the fixture in the tin plating bath of the tin plating equipment for tin plating operation after loading is completed, the process further includes:

[0011] The conductive pins of the fixture are energized, so that every pin of all target products within the fixture is conductive.

[0012] Furthermore, each fixture contains six of the target products.

[0013] A second aspect of the present invention provides a fixture applied to a method for single-chip tinning of the aforementioned QFN frame-type products, comprising:

[0014] Fixture frame, clamps, and conductive pins;

[0015] The clamps are symmetrically arranged on both sides of the fixture frame in the horizontal direction, and the conductive pins are connected to the fixture frame at intervals;

[0016] The clamp has a square structure, and a mounting groove is provided on the surface of the clamp. Screws that penetrate the mounting groove are provided on adjacent sides of the clamp. The target product is placed in the mounting groove, and the screws are used to fasten the target product.

[0017] The number of fixtures is 2n, where n is a positive integer ≥ 1.

[0018] Furthermore, conductive pads are provided between the target product, the side wall of the mounting groove, and the screw.

[0019] Furthermore, the number of clamps is 6, and the 6 clamps are equally spaced on both sides of the fixture frame.

[0020] Furthermore, the conductive pins are symmetrically arranged at both ends of the fixture frame.

[0021] Furthermore, prior to the tinning process, the conductive pin is made conductive to every pin of all target products.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention provides a method and fixture for tinning single QFN frame products. The fixture uses conductive pads and screws to fix the single QFN frame product onto a jig, ensuring conductivity at each pin. The entire fixture is then installed in a tinning bath, simulating the state of the entire product line within the bath, ultimately completing the tinning process for each single product. This solves the problem of non-conductive pins after the product is cut into individual pieces, preventing tinning and electroplating. It perfectly simulates the pin connectivity of the QFN frame product before cutting, thus enabling a normal tinning process. The resulting tin layer has the same appearance and thickness as the entire tin-plated product line, meeting the requirements of the tinning process and effectively improving the yield rate of the production line and the reliability of the products. Attached Figure Description

[0024] Figure 1 A flowchart illustrating the method for tinning a single QFN frame-type product provided by this invention;

[0025] Figure 2 This is a schematic diagram of the structure of the fixture provided by the present invention;

[0026] Figure 3 This is a schematic diagram of the tin plating principle mentioned in this invention.

[0027] The attached figures are labeled as follows:

[0028] 1- Fixture frame, 2- Clamp, 3- Mounting slot, 4- Conductive pin, 5- Screw, 6- Conductive pad. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is intended merely to illustrate selected embodiments of this application and is not intended to limit the scope of protection claimed by this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0032] See Figure 1 This invention provides a method for tinning a single QFN frame-type product, comprising the following steps:

[0033] Step S1: Provide a fixture, load the cut single target product into the fixture, each fixture contains 2n target products, after loading, place the fixture in the tin plating tank of the tin plating equipment for tin plating operation.

[0034] Step S2: After tinning is completed, the fixture is removed and transferred to the cleaning tank of the tinning equipment to remove residual chemicals.

[0035] Step S3: After cleaning, remove the fixture and take out the tin-plated target product from the fixture. Observe and confirm the tin plating of each pin of the target product. After confirming that there are no errors, the tin plating process of a single target product is completed.

[0036] Where n is a positive integer ≥ 1, and the target product is a single QFN frame product.

[0037] Optionally, in step S1, before placing the fixture in the tin plating bath of the tin plating equipment for tin plating after loading, the process further includes:

[0038] The conductive pins of the fixture are energized, so that every pin of all target products within the fixture is conductive.

[0039] Optionally, each fixture may contain 6 of the target products.

[0040] Electroplating refers to the process of depositing a metal or alloy layer on the surface of a conductive material, such as a metal, by means of an electrolytic reaction in a solution using an external direct current.

[0041] Taking copper sulfate plating bath as an example (e.g.) Figure 3 (as shown)

[0042] Copper sulfate plating baths mainly consist of copper sulfate, sulfuric acid, and water, and may also contain other additives. Copper sulfate is the source of copper ions (Cu2+). When dissolved in water, it dissociates into copper ions, which are then reduced (gain electrons) at the cathode (workpiece) and deposited as metallic copper. This deposition process is affected by the conditions of the plating bath, such as copper ion concentration, pH, temperature, agitation, current, and additives.

[0043] The main reaction at the cathode is Cu. 2+ (aq) + 2e- → Cu(s)

[0044] During electroplating, the concentration of copper ions in the bath decreases due to consumption, affecting the deposition process. This problem can be solved in two ways: 1. Add copper sulfate to the bath; 2. Use copper as the anode. Adding copper sulfate is more complicated, requiring analysis and calculations. Using copper as the anode is simpler. The primary function of the anode is as a conductor, connecting the circuit. However, copper as the anode also has another function: oxidation (losing electrons) to dissolve into copper ions, replenishing the consumed copper ions.

[0045] The main reaction at the anode is: Cu(s) → Cu 2+ (aq)+2e-

[0046] Since the entire plating solution mainly consists of water, side reactions such as water electrolysis will also occur, producing hydrogen (at the cathode) and oxygen (at the anode).

[0047] Cathode side reaction: 2H3O+(aq)+2e-→H2(g)+2H2O(l)

[0048] Anode side reaction: 6H₂O(l) → O₂(g) + 4H₃O⁺(aq) + 4e⁻

[0049] As a result, a layer of metallic copper is coated on the surface of the workpiece. This is a typical mechanism of plating bath, but the actual situation is much more complex. Autocatalytic plating and immersion plating are also mentioned.

[0050] Because QFN frame products are not conductive after being cut into individual pieces, it is impossible to complete the tin plating process again. This invention has independently developed and designed a complete set of special fixtures for tin plating of individual products.

[0051] Fixtures such as Figure 2 As shown, the method for tinning a single QFN frame product as described above includes a fixture frame 1, a clamp 2, and conductive pins 4. The clamp 2 is symmetrically arranged on both sides of the fixture frame 1 in the horizontal direction, and the conductive pins 4 are connected to the fixture frame 1 at intervals.

[0052] The clamp 2 has a square structure and a mounting groove 3 is provided on its surface. Screws 5 that penetrate the mounting groove are provided on adjacent sides of the clamp 2. A single QFN frame product is placed in the mounting groove 3, and the screws 5 are used to fasten the single QFN frame product.

[0053] The number of clamps 2 is 2n, where n is a positive integer ≥ 1.

[0054] Optionally, conductive pads 6 are provided between each individual QFN frame product and the side wall of the mounting groove 3 as well as the screw 5. That is, conductive pads 6 are provided around each individual QFN frame product to prevent damage caused by friction between the product and the side wall of the mounting groove 3 or the screw 5.

[0055] In this embodiment, the conductive pad 6 can be a rubber strip wrapped in tin foil.

[0056] Optionally, the number of clamps 2 is 6, and the 6 clamps 2 are equally spaced on both sides of the fixture frame 1.

[0057] Optionally, the conductive pins 4 are symmetrically arranged at both ends of the fixture frame 1.

[0058] Optionally, before the tinning process, the conductive pin 4 is made conductive with each pin of all single QFN frame products.

[0059] The specific process for using this fixture is as follows:

[0060] 1. Manually load the cut individual products (i.e. QFN frame products) into the mounting slot 3 of the above-mentioned fixture. Place rubber strips wrapped with tin foil around the product and then fix the product with two screws 5. Each fixture can load 6 products at a time. After loading, the products can be placed directly into the tin plating tank of the tin plating equipment and the tin plating operation can be carried out using the normal tin plating process parameters.

[0061] 2. After tinning is completed, remove the jig from the tinning equipment's tin plating tank and transfer it to the tinning equipment's cleaning tank to remove residual chemicals.

[0062] 3. After rinsing with clean water, remove the fixture from the tinning equipment cleaning tank, and take out the tin-plated product from the installation tank 3. Check the tin plating status of each pin of the product under a 45x microscope. After confirming that there are no errors, the tinning process of a single product can be completed.

[0063] The fixture provided by this invention uses conductive pads 6 and screws 5 to fix individual QFN frame products onto clamp 2, ensuring conductivity for each pin of the individual QFN frame product. The entire fixture is then installed in a soldering bath to simulate the state of the entire product line within the bath, ultimately completing the soldering process for each individual product. This solves the problem of non-conductive pins after the product is cut into individual pieces, preventing soldering and electroplating. It perfectly simulates the pin connectivity state of the QFN frame product before it is cut into individual pieces, thus achieving a normal soldering process. The resulting solder layer has the same appearance and thickness as the entire tin-plated product line, meeting the requirements of the product soldering process and effectively improving the yield rate of the production line and the reliability of the products.

[0064] The above description is merely the preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A jig, characterized in that, include: Fixture frame, clamps, and conductive pins; The clamps are symmetrically arranged on both sides of the fixture frame in the horizontal direction, and the conductive pins are connected to the fixture frame at intervals; The clamp has a square structure, and a mounting groove is provided on the surface of the clamp. Screws that penetrate the mounting groove are provided on adjacent sides of the clamp. The target product is placed in the mounting groove, and the screws are used to fasten the target product. The number of the fixtures is 2n, where n is a positive integer ≥ 1; The process of tinning a single QFN frame product using the aforementioned fixture includes the following steps: A fixture is provided, and the cut single target products are loaded into the fixture. Each fixture contains 2n target products. After loading, the fixture is placed in the tin plating tank of the tin plating equipment for tin plating operation. After tinning is completed, the fixture is removed and transferred to the cleaning tank of the tinning equipment to remove residual chemicals; After cleaning, the fixture is removed, and the tin-plated target product is taken out of the fixture. The tin plating of each pin of the target product is observed and confirmed. Once it is confirmed that there are no errors, the tin plating process of a single target product is completed. The target product is a QFN framework product.

2. The fixture according to claim 1, characterized in that, Before placing the fixture in the tin plating bath of the tin plating equipment for tin plating operation after loading is completed, the process also includes: The conductive pins of the fixture are energized, so that every pin of all target products within the fixture is conductive.

3. The fixture according to claim 1 or 2, characterized in that: Each fixture contains 6 of the target products.

4. The fixture according to claim 1, characterized in that: Conductive pads are provided between the target product, the side wall of the mounting groove, and the screw.

5. The fixture according to claim 4, characterized in that: The number of clamps is 6, and the 6 clamps are equally spaced on both sides of the fixture frame.

6. The fixture according to claim 4 or 5, characterized in that: The conductive pins are symmetrically arranged at both ends of the fixture frame.

7. The fixture according to claim 6, characterized in that: Before the tinning process, the conductive pin is made conductive to every pin of all target products.

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