An SMT tin paste printing process

Abstract

The application discloses a kind of SMT tin paste printing processes, belong to SMT tin paste printing technical field, comprising: substrate is pasted in the lower of brush tin fixture, tin paste is printed into pad on substrate by the aperture on brush tin fixture, at least part aperture eccentricity is set in corresponding substrate pad;Electronic component is pasted to the tin paste of substrate, and the electronic component of eccentric printing tin paste is pasted on the side opposite to the offset direction of aperture on tin paste;Substrate is reflow soldered after electronic component pasting is completed, and the surface camber of tin paste is larger, so when electronic component is pasted on one side of tin paste, its one end will be padded to a certain height, and staff can control the mounting position of electronic component according to need, avoid collision with adjacent electronic component, tin paste melts on substrate pad when welding, and the position of electronic component on substrate pad is pulled to be correct, to ensure that welding element does not occur offset, to avoid bad welding.

Description

Technical Field

[0001] This invention belongs to the field of SMT solder paste printing technology, and specifically relates to an SMT solder paste printing process. Background Technology

[0002] With the rapid development of SIP (system-in-package) technology, higher requirements have been placed on the size of packaged devices. To meet the trend of miniaturization and micro-miniaturization of SIP modules, system-in-package requires smaller spacing and higher density in device layout to reduce the overall size of the SIP module. However, the reduction in the spacing between electronic components poses a significant challenge to SMT (Surface Mount Technology). Specifically, during SMT placement, adjacent components are prone to collisions, leading to defects such as missing components, broken components, etc.; after SMT reflow, component misalignment is likely to occur, resulting in short circuits or component collisions and contact defects. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an SMT solder paste printing process that allows for subjective control of the offset direction of electronic components before and after soldering, thereby avoiding poor placement or soldering and improving soldering yield.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] An SMT solder paste printing process includes: placing a substrate under a soldering fixture; printing solder paste onto pads on the substrate through openings in the soldering fixture, wherein at least a portion of the openings are eccentrically positioned on the corresponding substrate pads; mounting electronic components onto the solder paste on the substrate, wherein the electronic components mounted on the eccentrically printed solder paste are located on the side of the solder paste opposite to the offset direction of the openings; and reflow soldering the substrate after the electronic components have been mounted.

[0006] Furthermore, the openings corresponding to the two adjacent substrate pads are located on opposite sides.

[0007] Furthermore, the electronic components are mounted on the opposite sides of the solder paste.

[0008] Furthermore, adjacent substrate pads are disposed at the center of the substrate.

[0009] Furthermore, the opening corresponding to the substrate pad located at the outermost edge of the substrate is located on the side of the substrate pad closer to the edge of the substrate.

[0010] Furthermore, the electronic components are mounted on the side of the solder paste closest to the center of the substrate.

[0011] Furthermore, the electronic component has component pads on its bottom, and the component pads are attached to the solder paste.

[0012] Furthermore, the soldering fixture is a stencil.

[0013] After adopting the above technical solution, the beneficial effects of the present invention are:

[0014] The SMT solder paste printing process of this invention includes: placing a substrate under a soldering fixture, printing solder paste onto pads on the substrate through openings in the soldering fixture, with at least some openings eccentrically positioned on the corresponding substrate pads; mounting electronic components onto the solder paste on the substrate, with the electronic components mounted on the eccentrically printed solder paste located on the side of the solder paste opposite to the offset direction of the openings; and reflow soldering the substrate after the electronic components have been mounted. The solder paste printed by this method has a large surface curvature, so when an electronic component is mounted on one side of the solder paste, one end is raised to a certain height. The operator can control the mounting position of the electronic component as needed to avoid collisions with adjacent electronic components. During soldering, the solder paste melts on the substrate pads, straightening the position of the electronic component on the substrate pads, ensuring that the soldered component does not shift and avoiding poor soldering. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of solder paste printing in the SMT solder paste printing process of this invention;

[0016] Figure 2 This is a schematic diagram of two adjacent electronic components mounted together.

[0017] Figure 3 This is a schematic diagram of electronic component mounting on the edge of a substrate;

[0018] Figure 4 This is a schematic diagram of the completed soldering state in the SMT solder paste printing process;

[0019] In the diagram, 1-substrate, 2-substrate pads, 3-stencil, 4-solder paste, 5-electronic components, 6-component pads. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] The directions mentioned in this manual are based on the attached diagrams and represent only relative positions, not absolute positions.

[0022] like Figure 1As shown, an SMT solder paste printing process includes the following steps: Step 1: Placing a substrate 1 under a soldering fixture, and printing solder paste 4 onto pads 2 on the substrate 1 through openings in the soldering fixture, with at least some openings eccentrically positioned on the corresponding substrate pads 2; Step 2: Mounting electronic components 5 onto the solder paste 4 on the substrate 1, with the electronic components 5 mounted on the eccentrically printed solder paste 4 located on the side of the solder paste 4 opposite to the offset direction of the openings; Step 3: Reflow soldering the substrate 1 after mounting the electronic components 5. In Step 2, one end of the electronic component 5 is raised to a certain height during mounting, causing that end to move outwards and avoid collisions with adjacent electronic components 5 at that end. In Step 3, during soldering, the position of the electronic component 5 on the substrate pads 2 is pulled straight by the surface tension of the solder paste 4, ensuring that the soldered component does not shift and avoiding soldering defects. Specifically, in Step 1, the soldering fixture is a stencil 3. In step three, the electronic component 5 has a component pad 6 at its bottom, and the component pad 6 of the electronic component 5 is attached to the solder paste 4.

[0023] like Figure 2 As shown, in step two, the openings corresponding to the two adjacent electronic components 5 are located on the side closer to each other, while the electronic components 5 are mounted on the side farther apart from each other on the solder paste 4. Because the spacing between the two adjacent electronic components 5 is small, the height of the solder paste itself can be used to raise the height of the adjacent electronic components 5 during placement, thereby avoiding contact between adjacent electronic components 5, resulting in defective placement such as component knocking, missing components, or component breakage.

[0024] like Figure 3 As shown in the figure, the left side of substrate 1 is the edge. In step two, the opening corresponding to the electronic component 5 located at the outermost edge of substrate 1 is set on the side of substrate pad 2 near the edge of substrate 1. Electronic component 5 is mounted on the side of solder paste 4 near the center of substrate 1. After soldering, electronic component 5 will not deviate from the edge of substrate 1, avoiding affecting processes such as cutting the edge of substrate 1.

[0025] Among them, the electronic components 5 with small adjacent spacing are arranged at the center of the substrate 1, which can avoid the situation where increasing the distance between adjacent electronic components 5 and moving away from the edge of the substrate 1 cannot be taken into account.

[0026] like Figure 4 As shown, in step three, during soldering, solder paste 4 melts on the substrate pad 2, pulling the electronic component 5 to the correct position on the substrate pad 2, so that the position of the electronic component 5 does not shift, avoiding short circuits or component collisions and other defects.

[0027] The SMT solder paste printing process of this invention involves setting the openings on the stencil corresponding to the substrate pads off-center. Electronic components are mounted on one side of the solder paste at the openings, and the mounting direction of the electronic components is opposite to the offset direction of the openings. This allows one end of the electronic component to be lifted outwards during mounting, avoiding collisions with adjacent electronic components at that end. During soldering, the electronic components are straightened, thereby achieving subjective control over the offset direction of the electronic components before and after soldering, avoiding poor placement or soldering, and improving soldering yield.

[0028] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the described embodiments are merely some, not all, of the present invention. These are merely illustrative examples, and the scope of protection of the present invention is defined by the claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention and without any inventive effort, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An SMT solder paste printing process, characterized in that, include: The substrate is placed below the soldering fixture, and solder paste is printed onto the pads on the substrate through the openings on the soldering fixture. The openings are eccentrically located on two adjacent substrate pads, and the openings corresponding to the two adjacent substrate pads are located on the side that is close to each other. Two adjacent electronic components are mounted on the solder paste of the substrate. The electronic components mounted on the eccentrically printed solder paste are located on the side of the solder paste opposite to the offset direction of the opening. The two adjacent electronic components are mounted on the side of the solder paste that is far away from each other. When two adjacent electronic components are mounted, the ends that are close to each other are raised to a certain height, so that the ends are moved away from the outside. After the electronic components are mounted, the substrate is reflow soldered, and the position of the electronic components on the substrate pads is pulled straight by the surface tension of the solder paste.

2. The SMT solder paste printing process according to claim 1, characterized in that, The adjacent substrate pads are located at the center of the substrate.

3. The SMT solder paste printing process according to claim 1, characterized in that, The opening corresponding to the substrate pad located at the outermost edge of the substrate is located on the side of the substrate pad closer to the edge of the substrate.

4. The SMT solder paste printing process according to claim 3, characterized in that, The electronic components are mounted on the side of the solder paste closest to the center of the substrate.

5. The SMT solder paste printing process according to claim 1, characterized in that, The electronic component has component pads on its bottom, and the component pads are attached to the solder paste.

6. The SMT solder paste printing process according to any one of claims 1 to 5, characterized in that, The soldering fixture is a steel mesh.

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