A、焊接原理

The principle of soldering:

电源通过输出电流加热电极和工件，电极传热给工件，工件达到一定的温度时预置于焊接位置的焊锡熔化，熔化后的焊锡通过毛细作用流入焊接接缝中，与镀层发生扩散与互相溶化，冷确后形成牢固的接头。这里，加热方式、加热过程、焊接温度、保温时间、焊料与助焊剂等是影响焊接质量的重要因素。

The power supply outputs current to heat the electrode and workpiece. As the workpiece temperature climbing to a certain value, the solder is pre-placed on the joint, and then the solder is melt and flows into the gap of joint with capillary action. The tin and plating layer will diffuse and compose each other. This forms a firm joint. In the whole process, there are many factors affecting the welding quality, such as the heating mode, heating duration, welding temperature, heating preservation time, the solder and flux to be used.

考虑到整个焊接过程方便、稳定可靠，推荐采用带温度控制的热压焊加热电源。加热曲线如图1所示。

Considering the convenience and stability, the hot pressure ( reflow) welding power supply is suggested. The whole heating curve can be shown in Fig.1.

图中加热的过程包括预升温、预热温度保持（t₁－t₂），焊接升温、焊接温度保持和冷却等阶段。可以通过调节温度的上升速度V₁、V₂来保证工件的加热速度符合焊接加热规律需求，同时设置t₁－t₂、t₃－t₄的时间间隔来调节预热阶段和焊接阶段的保温时间、保证加热均匀、接头形成稳定一致，随后冷却使焊料凝固，达到最佳的焊接效果。

The heating process includes five stages: temperature first up-sloop stage, pre-heating stage, welding temperature up-sloop, welding and cooling down. These keep the heating of the workpiece smoothly by adjustment of heating speed V₁、V₂ . At the same time, we can set the time of each stage to assure the welding quality.

B、主要构成：

Composition

电源

Power supply

采用热压焊类型的直流输出的逆变电源。逆变频率1kHz。电源基本参数如下：

The inverter similar as hot pressure welding is adopted. The inverting frequency is 1 kHz. The main parameters are as following:

额定功率：4kVA 或7kVA

Rated power: 7kVA or 4kVA

负载持续率：50％

Duty cycle: 50%

各阶段温度控制范围：50－600℃

Temperature setting range: 50～600℃

温度控制误差：≤±5℃

Error of temperature: ≤±5℃

预热时间：0.1-10s

Warm-up time: 0.1-10s

焊接保温时间：0.1-10s

Heating-maintain time: 0.1-10s

升温速度：20－200℃/s

Calefactive rapidity: 20－200℃/s

温度校正设定

Temperature adjustment

电极（带热电偶测量）

Electrode (measurement with thermocuple)

电极材料拟用钛合金，并尝试采用铜合金，最后通过试验决定。电极形状尺寸依据工件设计。热电偶设在电极前端靠工件的部位。

The material of the electrode will be confirmed by the experiment. The titanium alloy or copper alloy is no bad material. The shape of electrode is designed basing on the workpiece. The thermocouple will be placed in the electrode forepart near the workpiece.

C、具备性能特点

Performance and characteristic

电源响应快，温度曲线平稳

Response rapidly, balanced temperature curve.

逆变电源时间调节分辨率可达1ms（1kHz逆变频率），相对工频交流电源的20ms（50Hz），反馈控制周期大大缩短，可以将温度控制得更加平稳、准确。直流输出也使得热效率提高，温度波动小。

The controlling cycle is 1 ms with the 1 kHz invert frequency. It is the 1/20 of industry frequency welding power supply. The control precision is improved remarkably. It supplies the chance to controlling the temperature exactly.

零件温升的影响小，焊接质量好.

The effect of the workpiece temperture rising is little, high welding quality.

升温、保温分阶段精确控制，确保工件热平衡，避免工件过热，抑制对元器件的影响，同时也保证焊接质量稳定可靠。

The warm-up stage and heating-maintaining stage is divided in the heating process. So it ensures the heating balance and avoids the over-heating. It brings the high quality product.

温度显示功能

Temperature display

焊接温度面板实时显示。考虑到热电偶检测温度与焊接节点温度存在偏差，该系统提供温度校准功能，确保实时显示较准确的焊接接头处的温度。

The temperature of welding is real time displayed. As the temperature of the point detected by the thermocouple and welding point is different, the temperature adjustment part is included in this system to assure the veracity of the welding point temperature.

电极保护

Electrode protection

针对目前所使用电极易氧化，需经常维修的状况，该方案所提供的电源有利于克服目前方法易产生过热而损伤电极的缺点，减少电极维护次数，同时也延长了电极的使用寿命。

The power supply in this project avoids the shortcoming of electrode abrasion brought by the over-heating. So it reduce the maintain time and extend the duration.