Lead-free tin-sprayed circuit board
By setting different slot length compensation values for horizontal and vertical PTH slots on the circuit board, the problem of inconsistent slot lengths during lead-free soldering was solved, achieving precise control of slot length and meeting design requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- RAYBEN TECH (ZHUHAI) LTD
- Filing Date
- 2025-05-20
- Publication Date
- 2026-05-01
AI Technical Summary
In the existing technology, during the lead-free soldering process, it is difficult for the lengths of the horizontal and vertical PTH slots to simultaneously meet the design requirements. The horizontal slots are too large, and the vertical slots are too small. Moreover, the existing drilling compensation methods cannot effectively solve this problem.
Horizontal and vertical PTH slots are set on the circuit board, and different slot length compensation values are assigned to them. The compensation value V1 for horizontal slots is 0.1mm, and the compensation value V2 for vertical slots is 0.175mm. The slot length deviation is controlled within 75μm by adjusting the difference in the slot length compensation values.
It achieves effective control over the length of horizontal and vertical PTH slots, ensuring that the slot length is within the set range and meets the design requirements.
Smart Images
Figure CN224192131U_ABST
Abstract
Description
Lead-free solder plating circuit boards Technical Field
[0001] This utility model relates to the field of circuit boards, specifically to a lead-free tin-plated circuit board. Background Technology
[0002] PTH (Plain Hole) slots on a circuit board connect conductive lines across different layers or are used to insert components. They are created by depositing a conductive metal, such as copper, onto the insulating hole walls of the PCB using chemical plating and electroplating methods. Typically, the surface of the PTH slots requires lead-free solder plating to protect the copper layer and improve solderability. As shown in Figure 1, a typical procedure for lead-free solder plating of PTH slots involves immersing the circuit board vertically (in the direction of gravity) into a solder bath. After the circuit board is removed from the bath, the solder within the slots is blown out using front and rear air blades.
[0003] Lead-free solder plating is a rough process, so the size of the slots after lead-free solder plating is difficult to meet design requirements, necessitating drilling compensation. In existing technology, the drilling compensation for horizontal and vertical PTH slots on the circuit board is consistent. However, the applicant found in actual production that the front and rear air knives could not fully blow out the solder at the bottom of the vertical PTH slots, while the horizontal PTH slots did not have sufficient solder accumulation. As a result, the slot length of the horizontal PTH slots was too large, and the slot length of the vertical PTH slots was too small. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the main purpose of this utility model is to provide a lead-free tin-plated circuit board that can effectively control the slot length of both horizontal and vertical PTH slots.
[0005] To achieve the above-mentioned main objectives, this utility model provides a lead-free solder plating circuit board, which has horizontal PTH slots and vertical PTH slots; wherein, the horizontal PTH slots and vertical PTH slots include insulating slots, and the walls of the insulating slots are provided with copper layers and tin layers; the horizontal PTH slots have a first slot length compensation value V1, and the vertical PTH slots have a second slot length compensation value V2, wherein the second slot length compensation value V2 is greater than the first slot length compensation value V1.
[0006] Furthermore, 0.05mm <V2-V1<0.1mm。
[0007] Furthermore, V2-V1=0.075mm.
[0008] According to a specific embodiment of the present invention, the first groove length compensation value V1 is 0.1 mm, and the second groove length compensation value V2 is 0.175 mm.
[0009] Furthermore, the tin layer thickness of the horizontal PTH slot and the vertical PTH slot is 1μm to 40μm.
[0010] The technical solution of this utility model has the following beneficial effects:
[0011] In this invention, PTH slots in different directions on the circuit board have different drilling compensations. Specifically, horizontal PTH slots have a relatively small first slot length compensation value V1, and vertical PTH slots have a relatively large second slot length compensation value V2, which can simultaneously control the slot lengths of both horizontal and vertical PTH slots within a set range.
[0012] To more clearly illustrate the purpose, technical solution, and advantages of this utility model, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description
[0013] Figure 1 is a schematic diagram of the lead-free solder plating operation process;
[0014] Figure 2 is a schematic diagram of the lead-free tin-plated circuit board in the embodiment;
[0015] Figure 3 is a schematic diagram of the structure of the lead-free solder spraying groove. Detailed Implementation
[0016] The technical solution of this utility model is described in detail below with reference to specific embodiments. However, this utility model can also be implemented in other variations based on this description. Therefore, the protection scope of this utility model is not limited to the specific embodiments disclosed below.
[0017] As shown in Figure 2, the lead-free solder plating circuit board 1 of this embodiment has horizontal PTH slots 21 and vertical PTH slots 22; the orientation descriptions of "horizontal" and "vertical" refer to the posture of the circuit board 1 during the lead-free solder plating process. As shown in Figure 3, both the horizontal PTH slots 21 and the vertical PTH slots 22 include insulating slots 20a, and the walls of the insulating slots 20a are provided with a copper layer 20b and a tin layer 20c. The thickness of the copper layer 20b is 15μm to 40μm (e.g., 20μm or 25μm), and the thickness of the tin layer 20c is 1μm to 40μm.
[0018] In the prior art, the drilling compensation for both the horizontal PTH slot 21 and the vertical PTH slot 22 is 0.15mm. Because the front and rear air knives cannot fully blow out the solder at the bottom of the vertical PTH slot 22, and the horizontal PTH slot 21 does not have solder, the result is that the slot length of the horizontal PTH slot 21 is too large and the slot length of the vertical PTH slot 22 is too small.
[0019] To address the aforementioned issues, in this embodiment, the horizontal PTH slot 21 and the vertical PTH slot 22 are configured with different slot length compensation values: the horizontal PTH slot 21 has a first slot length compensation value V1, and the vertical PTH slot 22 has a second slot length compensation value V2, wherein the second slot length compensation value V2 is greater than the first slot length compensation value V1. Specifically, the first slot length compensation value V1 is set to 0.1 mm, and the second slot length compensation value V2 is set to 0.175 mm. By applying different slot length compensations to the horizontal PTH slot 21 and the vertical PTH slot 22, the deviation of their actual slot lengths from the standard slot length can be controlled within 75 μm.
[0020] Specifically, the slot length compensation value is the difference between the drilled slot length of the insulating slot 20a and the standard slot length of the finished PTH slot. For example, if the standard slot length of the transverse PTH slot 21 is 5.1 mm, then the drilled slot length of the insulating slot 20a is 5.2 mm, that is, the first slot length compensation value V1 is 0.1 mm.
[0021] In this invention, the method for manufacturing the PTH slot includes the following steps:
[0022] First, insulating slots 20a are drilled in the circuit board. Then, a copper layer 20b is deposited on the wall of the insulating slots using chemical plating and electroplating methods. Finally, lead-free tin plating is performed on the surface of the copper layer 20b to obtain a tin layer 20c. During lead-free tin plating, the circuit board 1 is immersed in the tin bath with its surface perpendicular to the horizontal direction. At this time, the length direction of the horizontal PTH slot 21 is parallel to the horizontal direction, and the length direction of the vertical PTH slot 22 is parallel to the vertical direction.
[0023] Although the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the present invention. Any person skilled in the art may make some modifications or variations without departing from the scope of the present invention; that is, all equivalent changes made in accordance with the present invention should be covered by the protection scope of the present invention.
Claims
1. A lead-free solder plating circuit board, comprising horizontal PTH slots and vertical PTH slots, characterized in that: The horizontal PTH slot and the vertical PTH slot include insulating slots, the walls of which are provided with a copper layer and a tin layer; the horizontal PTH slot has a first slot length compensation value V1, and the vertical PTH slot has a second slot length compensation value V2, the second slot length compensation value V2 being greater than the first slot length compensation value V1.
2. The lead-free tin-plated circuit board according to claim 1, characterized in that: 0.05mm <V2-V1<0.1mm。 3. The lead-free tin-plated circuit board according to claim 2, characterized in that: V2-V1=0.075mm.
4. The lead-free tin-plated circuit board according to claim 1, characterized in that: The first groove length compensation value V1 is 0.1 mm, and the second groove length compensation value V2 is 0.175 mm.
5. The lead-free tin-plated circuit board according to claim 1, characterized in that: The tin layer thickness of the horizontal PTH slot and the vertical PTH slot is 1μm to 40μm.