标签: connector

随着科技的日新月异，高速影音数据传输的需求也不断进化，例如 HDMI 的规范从 HDMI 2.0 发展到 HDMI 2.1 ，传输速率由 6.0 Gbps 发展至为 12Gbps ，让影像传输的效率更上一层楼；又如 USB 3.2 Gen 2 的最大传输速度为 10 Gbps ，为了让速度快上加快， USB-IF 协会已推出 USB 4 Gen3 让传输速度跃升至双通道 40Gbps. 然而，当用户在追求绝佳传输质量与实时性的那一刻，线材的稳定性和优劣必然会直接影响到使用者体验；举例来说，当使用者将未认证的线缆插上设备后，常会发生装置无反应的情况。 一. 阻抗不匹配 (Impedance NOT Matching) 阻抗匹配（ Impedance Matching ）是指为了使信号功率能从信号源（ source ）到负载（ load ）得到最有效的传递，让信号在传递过程中尽可能不发生反射现象。 Issue ：阻抗不匹配若发生时，会形成反射、能量无法传递，不仅降低效率还会产生震荡、辐射、干扰等不良影响。 二. 串音干扰 (Crosstalk) 两条信号线之间的耦合干扰现象，可分为近端及远程干扰。 Issue ：串音干扰发生时，会影响信号完整性。 三 . 频域的衰减 (Attenuation) 高频信号由 A 传递至 B ，于传输过程中产生的信号损失以及各种损耗成分的总和。 Issue ：频域的衰减发生时，会造成信号传导不良，降低效率等不良影响。 四 . 反射损失 (Return Loss) 高频信号由 A 传递至 B ，于传输过程中产生的信号损失以及各种损耗成分的总和。 Issue ：频域的衰减发生时，会造成信号传导不良，降低效率等不良影响。 五 . 衰减串音比 ACR (Attenuation to Crosstalk Ratio) 远程串音与衰减的差值。 Issue ：当 ACR 发生时，即代表 Crosstalk 与 Insertion Loss 可能也有相应的问题发生，造成信号完整性可能有所影响及讯号效率降低的不良情况产生。 高频治具解决方案应用于实际案例 我们以测试验证和实际上遇到的案例提供客制化高频治具解决方案，可逐一对应，让您的产品无论从开发初期到上市都能保有良好的质量。以下为百佳泰在高频治具设计上所搜集的一些案例： Example 1 : 待测物 pin 脚与治具板连接处，接触面所造成的阻抗不匹配（ Impedance not Matching ） : 解决方案 ：减少待测物 pin 脚与治具板连接处，因电容效应过大而造成阻抗偏低的影响。 Example 2: 客户连接器加工方式所造成的 Insertion Loss 影响 解决方案 ：改善加工方式，减少 Insertion Loss 。 Example 3: 同一平面，相邻太近的 Trace ，造成 Crosstalk 的现象 解决方案 ：相邻的 Differential pair 采不同层面的走线方式，减少信号太近造成的串音干扰。同时利用贯穿孔（ via ），缩短信号的 Return Path 。 Example 4: HDMI ACR Test Failed 解决方案 ：由于 ACR 是测试 远程串音与衰减的差异值，藉由减少 Crosstalk & Insertion Loss 来让 ACR test 更容易通过。 高频常见问题与改善方案案例分享 为协助您的产品从开发初期到上市都能拥有良好的质量，百佳泰搜集了实际测试中最常发生问题的以下三个 Potential Risks ，以此作为分享 : n Impedance not matching 阻抗不匹配 n Attenuation 衰减 n Crosstalk 串音干扰 案例 1 ： A 公司的 HDMI 2.1 Receptacle Connector 测试时， Receptacle 端的 CLK Trace 阻抗就算为 95. 809Ω ，但 Insertion Loss 表现不见得为佳。 Impedance: 95.809Ω （ 改善前 ） : Insertion Loss （ 改善前 ）： 解决方案 ： 连接器加工方式所造成的 Insertion Loss 影响，重新检视 Receptacle 端的焊接问题 ， 即有所改善 ， 所谓眼见不一定为凭 ， 即为此例。 Insertion Loss （ 改善后 ） : 案例 2 ： B 公司的 USB3.0 Type A Receptacle Connector 其 D+ & D- pin SMD pad 面积大，焊接时更要注意阻抗匹配的问题，否则容易造成接触面 Impedance 偏低的状况发生。 解决方案 ： 此例的焊锡量要少，并确保 connector pin 与 PCB pad 平贴，才能减低 connector pin 与 PCB pad 接触面阻抗不匹配的情况发生。 改善后 ： 案例 3 ： C 公司的 TBT3 的 Receptacl e C onnector 其 RX2_P & RX2_N IRL(Integrated Return Loss) 在标准附近未过， PCB 阻抗设计或是 connector 内部设计都有可能是原因之一。 解决方案 ： 经过比对确认 ， 此案例虽然 Trace 设计阻抗为 50Ω ，但实际状况下阻抗却不见得会落在 50Ω 左右，故设计时可提高 PCB 设计阻抗以避免此风险。 改善后 ： 案例 4 ： D 公司的 Type A Receptacle connector 设计为 pin 脚为深入铁壳内的设计 ， 测试过后此设计会造成 Near End Crosstalk(SS ： TX/RX) 超过协会规范 (3.6mV) 而F ail 。 解决方案 ： 经过验证，其问题点为铁壳内部的 GND 所造成，加强内外部铁壳与 PCB GND 连接其信号完整性才会提高而通过规范。 改善后 ： 3.5948mV 案例 5 ： E 公司的 HDMI 2.1 Receptacle Connector 为 Dip 孔设计型式 ， 因其本身连接器设计之故 ， 测试时会有 CLK Insertion Loss Fail 的情况发生。 Insertion Loss FAIL （ 改善前 ） : 解决方案 ： 调整 Dip 孔与 GND 距离 ， 使其 Impedance 升高或降低 ， 再观察 Insertion Loss 变化 ， 此案为降低阻抗即能有所改善。 Insertion Loss Pass （ 改善 后 ） ： 高频治具的开发设计，俨然已成为连接器、线缆验证不可或缺的一环。 通过以上所举例出的的案例，都显示出高频设计上的一些不能轻忽的要点，从设计规划、治具焊接、再到加工方式，每一步的操作都会影响到高频性能。尤以焊接部分为例，轻则影响信号表现，重则阻抗不匹配或是 IL 以及 RL 不佳而使高频信号失真，这是在高频版设计上所不能轻忽的。

My father and I jokingly share that the main reason for divorce in the US has to be putting up the Christmas tree (specifically, stringing lights). Each year it is about the most painful four hours of my life. It only takes about two hours to string all the lights on our nine-foot tree, but I inevitably dedicate another two hours to replacing burned-out bulbs and identifying dangerous strands or sockets (side note: our family can't stand the flicker associated with LED bulbs).   Worst connectors ever! Christmas tree light sockets have to be the worst connector ever designed. First, they are nearly impossible to remove. The bulb base fits almost flush into the socket. There's no lip or feature to pull on—enter broken and bloodied fingernails. Plus, the retention has to be in the hundreds of pounds. I often find I need surgical tools to remove them. Second, they provide for ridiculously poor and unreliable contact. About a quarter of the bulbs that are out just make poor contact and removal/reinsertion fixes the issue. Third, they're all just different enough that they aren't interchangeable. I have a collection of bags with different types. I inevitably have to swap bulbs between base types. That's a plus—at least the bases are easy to swap. This got me to thinking, what makes a good connector? This may sound obvious, but do connector designers have guidelines or best-practices? I would recommend the following: Electrical performance. This goes without saying. Most connectors do this well, matching the electrical properties for the application. Ease of assembly. Make the connector easy to assemble (by hand or automated) with minimal special tooling. Ease of disassembly. See No. 1 above. Usually neglected because, well, most connectors don't have to be disassembled. Ease of connection/separation. Use simple locking features that make connections quick and easy. Reliability. Both electrical and mechanical... make sure it holds up to the environment. Compatibility. I realise there is a marketing component to this, but the more "open" and compatible a connector standard is, the better.   Todd Marcucci VP Research Development Good Earth Energy Conservation Inc Note: This article appeared in 2012 on The Connecting Edge, but the connector problems remain.

Today's fiber-optic connectors have the amazing mechanical precision that allows low-loss mated pairs, especially considering that single-mode fiber has an optical core of about 9 microns in diameter. Two of these cores, from opposing fibers, must be aligned with almost-perfect mechanical precision to affect the least amount of optical loss.   Positive contact and angled polish keep losses and reflections to a minimum. Of course, this small core size means that the slightest speck of dust on the single-mode core can introduce disastrously high levels of loss, so absolute cleanliness (cleaning the end faces of the connector ferrules) is a must every time a connection is made.     It was not always this good. Quite a few years ago, optical fiber networking was becoming mainstream in the LAN arena. At that time, 50/125, 100/140, and later, 62.5/125 (core and cladding diameter in microns), multimode optical fiber sizes were the short-distance LAN choices. The large diameter core allowed optical launch using LEDs, rather than more costly and finicky lasers.   The 906 SMA optical connector was one of the first popular optical connectors, but it had a few annoyances. For example, a "Delrin sleeve" (hollow plastic cylinder) was required to mechanically align the ferrules of a mated pair, precisely enough that the loss should remain under 3 dB. Being detachable, these Delrin sleeves had a habit of falling on the floor and rolling under anything that prevented someone from ever finding them again.   Compared to today's connectors, with losses of a fraction of a dB, this 3dB loss spec was atrocious. But it was a fact of life, and we had to live with it.   One day, our lab technician was setting up the optical portion of our corporate network and ran into difficulty. He came to me for help because he was getting unexplained bit errors over all the optical links. We had just started manufacturing an Ethernet 10Base-T and FOIRL (Fiber Optic Inter Repeater Link) hub, but he was trying to use Cabletron optical transceivers at the desktop ends. Plus, he had set up an optical patch panel that added an extra mated pair per patch cord.   I had designed the optical cards for our own product. In spite of much complaining from production, I insisted on tweaks to ensure that the green "Link Good" indicator LED would not turn on unless the incoming optical signal level was sufficient to ensure a bit error rate of better than 10 -9 . This was a requirement of the FOIRL Specification.   The Cabletron folks did not want expensive tweaks, so they designed their gear with a "Link Good" indicator LED that turned on with the slightest optical input -- never mind that it was so weak that the bit error rate made the link unusable -- thus, their gear was not FOIRL compliant.   Our lab technician was fooled by the Cabletron desktop transceivers "Link Good" LEDs. I showed him, with my optical power meter, that the link was not good, and that the Cabletron LEDs were lying to him. Then I told him the only solution was to rearrange his patch panel to eliminate one of the two optical couplings -- use cord and splice bushing only, rather than splice bushing to patch cords to another splice bushing. This eliminated 2 dB to 3 dB of loss and the links worked.   Note: 3 dB of optical loss is equivalent to 6 dB of electrical loss.   Glen Chenier Engineer

The No. 1 cause for divorce in the US has to be putting up the Christmas tree (specifically, stringing lights). Well, that's just a joke between my father and me. Each year it is about the most painful four hours of my life. It only takes about two hours to string all the lights on our nine-foot tree, but I inevitably dedicate another two hours to replacing burned-out bulbs and identifying dangerous strands or sockets (side note: our family can't stand the flicker associated with LED bulbs).   Worst connectors ever! Christmas tree light sockets have to be the worst connector ever designed. First, they are nearly impossible to remove. The bulb base fits almost flush into the socket. There's no lip or feature to pull on—enter broken and bloodied fingernails. Plus, the retention has to be in the hundreds of pounds. I often find I need surgical tools to remove them. Second, they provide for ridiculously poor and unreliable contact. About a quarter of the bulbs that are out just make poor contact and removal/reinsertion fixes the issue. Third, they're all just different enough that they aren't interchangeable. I have a collection of bags with different types. I inevitably have to swap bulbs between base types. That's a plus—at least the bases are easy to swap. This got me to thinking, what makes a good connector? This may sound obvious, but do connector designers have guidelines or best-practices? I would recommend the following: Electrical performance. This goes without saying. Most connectors do this well, matching the electrical properties for the application. Ease of assembly. Make the connector easy to assemble (by hand or automated) with minimal special tooling. Ease of disassembly. See No. 1 above. Usually neglected because, well, most connectors don't have to be disassembled. Ease of connection/separation. Use simple locking features that make connections quick and easy. Reliability. Both electrical and mechanical... make sure it holds up to the environment. Compatibility. I realise there is a marketing component to this, but the more "open" and compatible a connector standard is, the better. We've all had dealings with questionable connectors. Maybe it was at a previous job or on a previous project. We've all used a connector at one point or another that made us think "What was that engineer thinking?" What are some of your "worst connector ever" experiences, and what additional best-practices do you think there should be? Todd Marcucci VP Research Development Good Earth Energy Conservation Inc Note: This article appeared in 2012 on The Connecting Edge, but the connector problems remain.  

Typically, medical devices are not supposed to smoke. You don't have to be the United States' Surgeon General to realise this. Early in my career, I was a newly hired engineer at a large medical device company. The first week my manager, Bernie, gave me full responsibility for supporting an existing product. I'll call it the Smoko-2. In my first week, I was invited to a "tear-down" session on the Smoko-2. The meeting started out great—the lead mechanical engineer praised the design, which used just one exposed screw to hold together the case and circuit boards. Things are looking rosy. People are smiling. Even the young ladies who assembled the units on the production line are smiling. Bernie himself isn't sweating and fidgeting as much as usual. Life was good. Then things turn ugly. One of the more experienced women on the repair line says, "Oh yeah, but we do get back some Smokos with melted and smoldering power cords." You could see the enthusiasm leak out of the room. I look around and the other engineers and managers look as bewildered as I am. Nice how they spring this on us at a very public meeting! There wasn't much sparkle or eye contact after that bombshell and the meeting quickly winds down. Bernie's forehead is glistening. He's playing the imaginary drums with two pencils. The discussion peters out to random monosyllables and the group quickly disperses, with some of us on the engineering team slinking away quietly as if hoping we're invisible. As the new engineer, I get the hairy eyeball from Bernie, and I don't need any further impetus. I go to pull the main Smoko-2.pdf drawing, and I see the problem right away. "Hmm, how did this ever happen?" I ask myself. The design required 9V at up to 2 amps be sent through a connector with 15 pins rated only at 1.5 amps each. So no problem, right? Since only 9 pins are needed for data, the designer allocated the remaining pins as follows: three to carry plus, three to carry minus. That is absolutely okay, in the theoretical plane. Plenty of current capability, 4.5 amps theoretical, 2 amps actual, a huge safety margin you think, sitting on your theoretical cloud. But in reality, this decision is a disaster waiting to happen. The connector mostly relies on gravity, the weight of the device on its charging stand, to make firm contact. And it expects the connector pins to be clean and perfectly straight and the device and base to be exactly perpendicular. None of these situations happen in the real world. Emergency rooms can be hectic, devices are not always carefully set down perpendicular into their chargers, and bits of crud and cleaning fluids can get into things. All it takes is a speck of a foreign object to interfere, and then we have 2 amps trying to go through not three pins, but maybe just two or even one. Push 2 amps through a 1.5 amp contact, maybe add a little smudge of medical salve or a speck of bandage cotton, and we have Smoke City, Utah. Bad show. At $880 for each Smoko-2, customers would expect it to not smolder. In an ideal world we would just redesign the whole thing—but that would be a huge deal—there is a real shortage of off-the-shelf connectors with nine or so data lines plus two heftier power lines. We might have to get a custom connector designed, new cases and charging stands and circuit boards and user guides made up, plus FDA clinical trials, easily a quarter-million dollar and year-long project. And we'd have to recall all the devices in use, a many-million-dollar hit. And the nice people on the production line will not be smiling at me in the future as they'd have to increase their build rate 20-fold to replace all the units out in the field. And poor me, I've been here two weeks and I have to tell my manager that "my" device needs a couple of million dollars in bandaging. I was downcast for several days, even considering going back to my first job, shoveling coal into a greenhouse boiler. While dirtier, it was nice warm work, and even if the worst happened and the boiler exploded, it wouldn't hurt as much as having to run through the view-graphs in front of the managers, especially the bar chart showing $2M of unplanned expenditures on my project. When a boiler explosion starts sounding like a good thing, you know you're in a pretty dark place. Fortunately, our dog Beau came to the rescue. He needs frequent walks to empty his output queue, if you know what I mean. During one of these long walks when I had plenty of time to think, an idea popped into my mind. No, not a perfect solution, but keeping with the medical genre, a band-aid, inexpensive, and just good enough to work. As luck would have it, there was just enough room inside the power connector to put a simple CMOS Schmitt-trigger to sense power abnormalities and a flip-flop to shut down the power. Another Schmitt-trigger could be coerced to act like an astable pulse generator, trying to turn on the flip-flop every few seconds to retry the power-on situation. Not a perfect solution, but one good enough to prevent major smoldering and a multi-million dollar recall. Bernie gave his go-ahead, I got to keep my job, C. Everett Koop stopped appearing in my dreams, I got a good job review six months later, and lived happily ever after. Well, until the next debacle. This story was submitted by George Gonzalez for Frankenstein's Fix, a design contest hosted by EE Times (US). George Gonzalez is by day, officially, a Software Guru, using his ancient degree in Computer Science, plus 35 years of experience, stirring up commercially useful mixtures of C, Delphi, Python, and assembly language. While his father and brother are both accomplished EE's, George just attacks hardware with some general principles learned at the school of hard knocks (and with safety glasses). At home George fawns over and repairs old tube radios from the 30s thru the 60s. At work, when there is no software to do, he is occasionally allowed to use his instincts to keep somewhat less ancient (designed in 1995) products in production.