IQD用石英基产品超声波清洗印刷电路板

The use of an ultrasonic-bath is a common method of cleaning electronic components and printed circuit boards (PCBs).

This method uses ultrasound and a solvent to clean items by creating cavitation bubbles which are produced by high frequency pressure (sound) waves to agitate the cleaning liquid, forcing contamination to be removed.

Ultrasound is sound beyond the normal hearing range of humans with a typical bath operating around 40kHz although other frequency equipment is available.

Modern ultrasonic cleaning baths may have the facility to alter the bath frequency and this is useful as it may help to reduce self-resonance by sweeping the frequency up and down thus helping to alleviate damage that may be created at one specific frequency.

To date, little research on the use of ultrasonic cleaning of quartz components has been done. The only generally available background information was published by GEC-Marconi, Hirst Research Centre in England in 1992 and titled The Effects of Ultrasonic Cleaning on Device Degradation — Quartz Crystal Devices. The authors of the report are surprisingly optimistic in the tone of their conclusions, despite finding many failures even in their small sample size. Failures were found to be significantly higher in low cost high volume quartz devices. However if considering this report, it is important to recognise that quartz crystal manufacturing has changed very dramatically in the intervening years. The size, packaging and mounting structure of modern ceramic packages are not comparable to the metal can packages analysed in this report, additionally the general quality control of low cost high volume manufacturing is very different today than in 1992. 

As a general comment, crystals in the MHz range (which use AT cut quartz blanks), should survive an ultrasonic cleaned process unharmed. Although the overall frequency and specification must be taken into account because higher frequencies use thinner quartz blanks which are more susceptible to breakage than thicker lower frequency devices.

However, crystals that use ‘tuning-fork’ technology to produce low frequencies such as the common 32.768kHz watch crystals are significantly higher risk. In their application these crystals are designed to work at very low drive levels, the internal architecture of these crystals is designed to excite resonance with very low input power levels, meaning higher power levels can cause physical damage more easily than other products. The frequencies used in ultrasonic are also much closer to the resonant frequency of the quartz, further increasing the likelihood of self-resonance. 

With the above points it can be seen that the use of ultrasonic cleaning on PCB’s containing quartz products is not without risks. For low frequency crystals, in the kHz range, IQD  Crystay do not recommend the use of ultrasonic cleaning. For other crystal types we recommend that experimentation is undertaken to assess the risk before use in production. 

If you are considering using ultrasonic cleaning in your production process then we would recommend that some experimentation is undertaken working with the specific vibration frequencies and energy levels that the components will see in your cleaning equipment to prove suitability. We also recommend that the specific crystal to be used on the PCB is used in the assessment experimentation. 

The Institute for Interconnecting and Packaging Electronic Circuits (IPC) paper IPC-TM-650, titled Test to Determine Sensitivity of Electronic Components to Ultrasonic Energy, this provides a good starting point for any experimentation. 

IQD用石英基产品超声波清洗印刷电路板

使用超声波浴池是清洗电子元器件和印刷电路板（pcb）的一种常用方法。

这种方法使用超声波和溶剂来清洗物品，产生空化气泡是由高频高压（声）波产生的气泡来搅拌清洗液，迫使污染被清除。

超声波的声音超出了人类的正常听力范围，一个典型的浴缸运行约40kHz，尽管有其他频率设备。

现代超声波清洗浴可能有改变浴频率的设备，这是有用的，因为它可能有助于减少自共振扫描频率，从而帮助减轻可能在一个特定频率造成的损害。

到目前为止，关于使用超声波清洗石英组分的研究还很少。唯一普遍可用的背景信息是由英国赫斯特研究中心gec-马可尼于1992年发表的，题为《超声波清洗对器件降解的影响——石英晶体器件》。该报告的作者对他们的结论的基调令人惊讶地乐观，尽管他们在小样本量中发现了许多失败。在低成本的高容量石英器件中，故障明显更高。然而，如果考虑到这个报告，重要的是要认识到石英晶振的制造在这几年里发生了非常巨大的变化。现代陶瓷包装的尺寸、包装和安装结构无法与本报告中分析的金属罐包装相媲美，此外，目前低成本大批量制造的一般质量控制与1992年非常不同。

一般来说，在MHz范围内的晶体（使用AT切割石英空白），应该在超声波清洗过程中安然存活下来。虽然必须考虑整体频率和规格，因为更高的频率使用更薄的石英坯料，比更厚的低频率设备更容易断裂。

然而，使用“音叉”技术产生低频率的晶体，如常见的32.768kHz手表时钟晶振，其风险明显更高。在它们的应用中，这些晶体被设计为在非常低的驱动水平下工作，这些晶体的内部结构被设计为在非常低的输入功率水平下激发共振，这意味着更高的功率水平比其他产品更容易造成物理损伤。在超声波中使用的频率也更接近石英的共振频率，进一步增加了自共振的可能性。

从以上几点可以看出，对含石英PCB的产品使用超声波清洗并非没有风险。对于低频晶体，在千赫兹范围内，IQD不建议使用超声波清洗。对于其他类型的晶体，我们建议在生产中使用前进行实验以评估风险。

如果您正在考虑在生产过程中使用超声波清洗，那么我们建议进行一些实验，使用组件将在您的清洗设备中看到的特定振动频率和能级，以证明其适用性。我们还建议在评估实验中使用将在PCB上使用的特定晶体。

互联和包装电子电路研究所（IPC）论文IPC-TM-650，题为确定电子元件对超声波能量灵敏度的测试，这为任何实验提供了一个很好的起点。