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  • 发布时间:2019-04-30 09:35
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  • 分类:新闻资讯
  • 作者:
  • 来源:
  • 发布时间:2019-04-30 09:35
  • 访问量:6

Spring contacts hold up during shock and vibration



Test results show these versatile components are durable and stable for such harsh environments as medical and military technology.



When selecting a connector for a given application, design engineers are faced with the challenge of balancing many needs, both technically and commercially. While many connector systems can be purchased off-the-shelf or through traditional sales channels, many standard products trade performance for wider market acceptance. 



Spring contact technology delivers a diverse range of building blocks, including:



Simplifying product design through elimination of mating counterparts;


Enabling higher-density connections where needed (0.4-mm between centers is       possible from stocked components); 

能够在需要地方进行更高密度的连接 (现有组件的中心距可以为 0.4 mm);

Shortening board-to-board heights to less than 3 mm;

将板到板高度缩短到小于 3 mm;

Extending product lifetime with greater than 50,000 reliable mating cycles; 

将产品寿命延长到 50,000 次可靠配接以上;

Exceptional blind mating characteristics, allowing for simple product assembly or relaxation of critical dimensions.



In addition, correctly specified spring contacts also offer a stable, highly consistent interface, even under the harshest conditions. These characteristics are why many top defense and medical technology companies choose spring contacts and connectors for interconnections. 




How the signal ‘sees’



Differentiating what appears to be a simple electromechanical component is critical in understanding how to select the correct contact for a given application. It is useful to understand how the internal design of these contacts aids their overall performance and durability. 



When defining “stable” and “consistent” in relation to a spring contact, it’s important to consider how the signal “sees” the connection medium and how this varies between mating cycles or during changes in the external environment, such as temperature or shock. This “path of least resistance” is useful in understanding how the signal will behave. The signal will transfer along the contact at different but distinct points, which for a single-sided contact can be classified and defined as R1, R2, and R3. Total resistance can be defined as R1+R2+R3, and so forth. 

定义弹针的“稳定性”和“一致性”时,切记要考虑信号是如何“看到”连接介质的,以及在配接与配接之间或温度或冲击等外部环境变化期间信号“看到”连接介质的结果的差异。“最小电阻路径”有助于了解信号的行为。信号将沿截然不同的触点传输,对于单端触点,可分类并定义为 R1、R2 和 R3。总电阻可定义为 R1+R2+R3,依此类推。 


•R1 is influenced by several factors, including the material and condition of the target and plunger, the surface area and shape of the plunger tip, and the amount of force applied. In general, the highest bearable force should be selected to minimize contact resistance; however, spring contact force can be modified easily by changing the internal spring design and/or material, or simply changing the compressed mechanical height at which the contact finishes. This lets you balance the total force of interconnect against board thickness or reinforcement to minimize flexing. For arrays of connectors, this can be a critical factor, as in eliminating additional weight for airborne or portable applications, which is normally required with incumbent connector technology.

•R1 受几个因素的影响,包括目标和顶杆的材料和状况、顶尖的表面积和形状以及所施加的力的大小。一般而言,最大可承受力的选择应最大程度地减少接触电阻;但是,弹簧接触力可轻易地通过更改内部弹簧设计和/或材料,或者简单地更改压缩机构接触高度来更改。这使你可以在连接的总作用力和板厚度或牢固度之间找到平衡,最大程度地减小挠曲。对于连接器阵列,这是一个关键因素,如为空中应用或便携应用(通常需要责任重大的连接器技术)消除额外的重量。




FIGURE 1. Spring contacts, shown here as stand-alones and as part of connector systems, stood up to rugged vibration testing conducted by the employer of this article’s author.

图 1.弹针,此处显示的是单独使用的或作为连接器系统的一部分,经过本文作者所在公司进行的严格振动测试。


One important benefit of spring contacts is that force is generated linearly and requires significantly less printed circuit board (PCB) real estate than conventional bent-metal or plug-and-socket systems, providing more room for functional components in the finished article. 

弹针的一个重要优点是作用力是线性产生的,与传统弯曲金属或插接系统相比,只需要极少的印刷电路板 (PCB) 空间,为成品中的功能组件提供更多的空间。 


Customized tips can also be accommodated to pierce or wipe away contaminants or surface oxides, although for the majority of applications, a spherical tip provides significant surface area to satisfy the most demanding of requirement. 



•R2 is the point of signal transfer between plunger and barrel. To ensure the signal avoids the long, thin, variable path that is the spring, mechanical systems referred to as bias are used. These systems reliably hold the plunger in contact against the internal barrel wall, providing a constant, sliding, low-resistance connection. The bias system ensures the resistance remains stable and consistent, irrespective of height, shock, or vibration. Several systems of bias exist. 

•R2 是顶针与套壳体之间的信号传输点。为了确保信号避免长而薄的可变路径(弹簧、机械系统),使用了偏置。这些系统可靠地将触弹针内的顶针固定到壳体内壁,提供恒定、滑动、低电阻的连接。偏置系统确保电阻保持稳定一致,不受高度、冲击或振动的影响。有几种偏置系统。 


In addition to bias, the manufacturing technique and plating of the barrel itself influences R2 over the lifetime of the contact. Deep drawn parts offer the ability to pre-plate the internal working faces with gold, while also work-polishing and hardening the wall to optimize product lifetime. Conversely, machined parts allow for flange-like mounting features, but are more challenging to internally plate. 

除了偏置以外,壳体本身的制造技术和镀层也会在弹针的整个使用寿命期限内影响 R2。深冲部件提供了对内部工作面镀金的能力,还可以在工作时抛光和硬化壳壁以延长产品寿命。相反地,机制部件允许法兰安装功能,但是内部镀层更有挑战性。


FIGURE 2. These reliable connector systems all use spring contacts.

图 2. 这些可靠的连接器系统全部使用弹针。



The bias-ball system is the most aggressive, providing a highly consistent connection between the plunger and barrel by compressing a ball against an angled plunger. With this system, contact lifetime is approximately 50,000 cycles, after which internal wear creates a less-stable connection. 

偏置球系统最有积极性,通过将球压到一个倾斜的顶杆,在顶针和客体之间提供极其一致的连接。通过这个系统,弹针的使用寿命约为 50,000 次,之后内部磨损将降低连接的稳定性。 


Bias-plunger and bias-spring systems are less aggressive, and subsequently deliver a less consistent, yet still acceptable, connection between plunger and barrel. Both systems use the spring or plunger instability against its counterpart to create the bias effect. The lifetime of such a system typically is 100,000 cycles maximum. 

偏置顶针和偏置弹簧系统的积极性较低,因而在顶杆和套筒之间提供一致性较低但仍可接受的连接。两种系统都使用弹簧或顶针相对于其配对体的不稳定性来形成偏置效果。此类系统的使用寿命通常最大为 100,000 次。


FIGURE 3. The eccentric bias system, which uses a contact with a backdrilled plunger, exhibits this typical resistance stability over multiple mating cycles.

图 3. 偏心系统,使用后钻孔顶针,显示多次配接时的典型电阻稳定性。


Patented technology called eccentric or E-bias uses a contact with a backdrilled plunger, maximizing possible stroke length and increasing the contact area between barrel and plunger to minimize signal loss. The backdrilled hole can be offset or angular to the spring’s natural center line and exploits the spring’s natural tendency to straighten, generating a sound side loading between plunger and barrel at all times. The benefit of such a system is stable low loss, coupled with a minimum 100,000-cycle lifetime. 

专利技术“偏心”或 E-bias 使用一个具有后钻孔顶针的触点,最大程度地增加冲击长度,增大套客体和顶针之间的面积,从而最大程度地减少信号损失。后钻孔可以偏离弹簧自然中心线,或与中心线呈一个角度,利用弹簧的自然趋势伸直,在顶针和客体之间始终形成一个可观的侧作用力。此类系统的优点是稳定的低损失,使用寿命至少可达 100,000 次。 


•R3 resistance is the point of transfer between the barrel and PCB. This figure is often negligible for many designs, but is influenced by board-termination technique. Standard surface-mount technology or through-hole techniques provide adequate performance. 

•R3 电阻是套客体与 PCB 之间的传输点。对于很多设计,这个数字通常可以忽略不计,但它受电路板终端技术的影响。标准表面贴装技术或通孔技术提供足够的性能。



Shock treatment


Performance under shock and vibration is often critical in performance applications. To better understand how spring contacts operate during such conditions, we have carried out extensive product testing on key bias types. The objective of the test process was to examine how the signal-path loss varied after exposure to different levels of vibration, and if discontinuities could be forced through long-term fretting wear or by unbiasing the spring contact with excessive shock. 



FIGURE 4. This cross-section of a typical spring contact shows its basic elements, all of which have an effect on the contact’s performance.

图 4. 典型弹针的剖面图显示了其基本元件,所有元件都会影响触点的性能。


Testing was conducted in accordance with EIA 364, with the product resistance measured initially and at each subsequent change in vibration, as follows: 

测试根据 EIA 364 进行,最初量得的产品电阻和以后振动中每次改变时量得的电阻如下:


Mechanical shock: 58 Gs, 11 milliseconds, 1⁄2 sine wave, 3 blows/direction/axis, 3 axis; 

机械冲击:58 Gs,11 毫秒,1⁄2 正弦波,3 击/方向/轴,3 轴;

Initial vibration: 3.1 Gs RMS to EIA 364 Procedure 28

初阶振动:3.1 Gs RMS,符合 EIA 364 程序 28

Power spectral density 0.02; 

功率谱密度 0.02;

50 to 500 Hz; 

50 至 500 Hz;

1 hour/axis, 3 axis;

1 小时/轴,3 轴;

Secondary vibration: 5.35 Gs RMS to EIA 364 Procedure 28

二阶振动:5.35 Gs RMS,符合 EIA 364 程序 28

Power spectral density 0.02;

功率谱密度 0.02;

50 to 2000 Hz; 

50 至 2000 Hz;

1 hour/axis, 3 axis;

1 小时/轴,3 轴;

Tertiary vibration stage: 7.56 Gs RMS to EIA 364 Procedure 28

三阶振动:7.56 Gs RMS,符合 EIA 364 程序 28

Power spectral density 0.04; 

功率谱密度 0.04;

50 to 2000 Hz; 

50 至 2000 Hz;

1 hour/axis, 3 axis;

1 小时/轴,3 轴;

Final vibration stage: 9.26 Gs RMS to EIA 364 Procedure 28

最后一阶振动:9.26 Gs RMS,符合 EIA 364 程序 28

Power spectral density 0.06; 

功率谱密度 0.06;

50 to 2000 Hz; 

50 至 2000 Hz;

1 hour/axis, 3 axis.

1 小时/轴,3 轴。


The results of this testing process demonstrate how any bias system improves contact performance, but an eccentric bias enables a reduction in piece-part count while retaining stability. 



FIGURE 5. This sample random vibration profile at 9.26G root mean square (RMS) on the Y axis shows stable performance.

图 5. 本示例在 Y 轴上随机进行振动,在 9.26G 均方根 (RMS) 处显示稳定性能。


Biased battery contacts offer exceptional stability during the most severe of shock conditions. 



The force needed to create a disconnect can be calculated using the following formula: 



Force = mass χ acceleration.

作用力 = 质量 χ 加速度。 



因此: Acceleration = force ÷ mass

   加速度 = 作用力 ÷ 质量 

where force is the spring force at rated stroke, and mass is the mass of the plunger. 



FIGURE 6. Within a spring contact system, the points of transfer are where the tip meets the target, where the barrel and plunger meet, and where the barrel meets the printed circuit board.

图 6. 在一个弹簧触弹针系统中,传输点是顶针与目标相接触的地方、客体与顶针相接触的地方以及套客体与印刷电路板相接触的地方。


For a typical bias ball spring contact: 


Force = 65.2g, mass = 0.01587g, and acceleration = 65.2 ÷ 0.01587, or 4108. 

作用力 = 65.2g,质量 = 0.01587g,加速度 = 65.2 ÷ 0.01587(即 4108)。


FIGURE 7. The eccentric bias system, a patented system shown on the far left, is fundamentally different from other bias systems, including ball, plunger, and spring.

图 7. 最左侧的偏心系统是一种专利系统,与其他偏置系统有根本性的不同,包括球、顶杆和弹簧。


To achieve disconnection, the contact must be exposed to well in excess of 4000 G shock. 

要实现连接中断,触点必须受到 4000 G 以上的冲击.



Spring into action 


Spring contacts in all form factors can be quickly engineered into highly reliable connector systems, including cabled, coaxial, surface-mount, and double-sided varieties. 



FIGURE 8. This is the classical shock profile derived from the EIA 364 Procedure 28, which is a vibration test.

图 8. 这是一个来自 EIA 364 程序 28 (振动测试) 的经典冲击曲线。


Spring contacts can be a useful tool in your design toolbox, exhibiting durability, stability, and the adaptability to meet many interconnect challenges. 



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