选择合适的导热材料
根据您的应用程序，您可能希望使用一种类型的 TIM 而不是另一种类型的 TIM，以帮助提高性能。有些是刚性的，有些是灵活的。一些 TIM 是实心的，而其他 TIM 可以在相之间变化。有多种热界面材料类型可用于改善表面之间的传热，但规范正确的类型至关重要。
Learn more about they types of Thermal Interface Materials below:
热界面材料类型列表：
填隙料
Gap fillers are a popular interface material type. Gap fillers are elastomeric sheets, typically made from silicone, that contain specialized thermal filler material to increase the overall thermal conductivity of the material. These materials come with a wide range of options, so it’s fairly easy to find a suitable gap filler for a specific application. Gap fillers are typically cut to standard device sizes or customized shapes for specific applications.
广泛的间隙填充材料选择
Gap fillers are probably the most diverse major thermal interface material type. All gap fillers have a base elastomer and a thermal filler mixed in, which include silicone and silicone-free materials. These are just a fraction of options available when selecting a gap filler. Within the same elastomer and filler mix, there are multiple sheet thicknesses, tacky or adhesive options for each side of the sheet, reinforcement materials like fiberglass, and carrier options for protecting the material before application. Some materials can electrically isolate hot devices. Other gap fillers have the ability to absorb electromagnetic interference (EMI). Between all of these options, you could have a hundred options with one material type. This range of options is what makes gap fillers a popular selection when it comes to thermal interface material.适应公差堆叠和带间隙填充物的多个设备
Since gap fillers are made from an elastomeric base material, it has a springy quality to it. This means it can be compressed and can apply pressure proportional to its deflection against the surfaces pressing against it. But instead of an axial spring, it’s an elastic surface that can be compressed varying amounts across its entire surface. This is why gap fillers are so effective in accommodating tolerance stack ups and multiple devices. Gap fillers will yield to varying heights, so if there’s a particular device where the tolerances stack up and have a bit of variance, the gap filler can still effectively connect a device to a heat sink. And it doesn’t need to be just one device, it could be multiple devices that need to connect to a single heat sink. With gap fillers, it’s possible.
某种可重复使用的热界面材料
填缝剂具有一定程度的可重复使用性。由于它们是弹性的，这些热界面材料具有弹回原位的能力。当我们用力过猛时，我们会在填缝剂中产生塑性变形，使其无法完全恢复其原始厚度。因此，如果我们保持在该范围内，我们可以再次使用间隙填充剂。如果填缝剂有粘合剂面，它可能无法很好地剥离，这也将限制其重复使用的能力。粘性或粘性表面还具有发现漂浮在周围的任何和每个颗粒的不可思议的能力，因此如果间隙填充物的拆卸和重新安装不在清洁和受控的环境中，表面可能会变脏。
导热膏
Thermal grease is a grease specially designed to have a high thermal conductivity. Most thermal greases are silicone based with small thermally conductive filler particles that increase the overall conductivity of the mixture. There are silicone-free greases on the market for applications that are sensitive to silicone. Applications that are concerned with the wettability and adhesion of surfaces that may come in contact with a thermal grease would benefit from using a silicone-free compound.广泛可用且常见的应用选择
Thermal grease is easy to acquire, making it popular for DIY projects or smaller quantity prototype or production runs. For applications that require consistency from one product to the next, it’s relatively simple to create a template for screening on thermal grease. This makes application specific grease patterns simple and cost effective. Other thermal interface materials require die cutting to produce custom shapes.低界面电阻，是平坦表面的理想选择
Applying pressure to thermal grease between two surfaces forces the grease to shear and spread thin between those surfaces. Minimizing the material thickness between the surfaces minimizes the thermal resistance your interface material will impose on heat transfers. This makes thermal grease ideal for flat and smooth surfaces. Rougher or more detailed surfaces with different heights have small pockets where the grease can’t quite fill, which is why other thermal interface materials like gap fillers were designed.Under Pressure: Spring Force Required
导热硅脂需要弹簧加载的安装力。当导热硅脂加热时，它会流出一点点并变薄。为确保两个表面始终接触并压缩润滑脂，最好使用弹性力来安装润滑脂表面。
Ginger Handling Required
Like any other grease, thermal greases can be tricky to clean up and keep contained well. In smaller quantities, grease is kept in tubes and syringes, allowing for more control over application. Larger quantities of thermal greases come in containers with big lids and applying grease from a open tub can make a mess.润滑脂不可重复使用
While there are many great things about thermal grease with is flexibility and ease of application, it comes with the drawback of not being reusable. After the grease is compressed and thins out, the grease can dry out and prevent reuse. Any attempt to reuse the grease is crumbly mess which will not meet earlier performance. The only way to get the same performance as before is to reapply fresh thermal grease. This is why manufacturers thermal solutions with thermal grease pre-screened on heat sinks in order to provide a consistent amount of grease along with a grease cover, to protect the grease until ready for installation.热垫和薄膜
导热垫和薄膜是用于将热量从一个表面传导到另一个表面的薄材料。这些界面材料也是远离热点散热的理想选择。除了少数导热垫和薄膜外，所有导热垫和薄膜都是柔性材料。与填缝剂一样，导热垫、薄膜和箔片通常被切割成标准设备尺寸或针对特定应用的定制形状。
Thermal Pads are typically made from a higher durometer silicone-based material than gap fillers. Like gap fillers, silicone pads also doped with more conductive materials like aluminum oxide or boron nitride. Additionally, thermal pads are reinforced by fiberglass or another material to increase tear resistance of the material. This makes thermal pads a robust and compliant replacement for thermal interface hardware.
Thermal films are commonly made of polyimide, a transparent thermoset polymer that has great electrical isolation properties. You’ll also hear it referred to as its brand name Kapton. Films can be made from other materials, like graphite, which we’ll get into in a moment.
电气隔离
Not all thermal pads and films are considered electrically insulating. For those that are electrically insulating, they’re becoming a more popular option than insulating hardware because of their flexibility, lightweight, and extremely thin properties. This is especially advantageous for consumer electronics that continue to pack more power and components into thinner devices. If you’ve got high power applications and require some level of flexibility or compliance with your thermal interface material, thermal pads or thermal films are the preferred choice.石墨垫和薄膜
石墨薄膜是导热垫或薄膜一般规则的例外。石墨垫由一堆石墨烯片层叠而成，因此热量和电很容易在片内键合在一起的碳原子之间传播。石墨烯片不会牢固地结合在一起，因为碳键已经在石墨烯平面中形成，而不是在石墨烯平面之间形成。 虽然在沿其平面传播热量方面非常出色，但与其他薄膜和焊盘相比，石墨薄膜相对脆弱和脆。它们也是非电绝缘的，因为电子可以很容易地穿过石墨结构。
While that being said, graphite interface materials can effectively replace thermal pastes or greases. Graphite materials are a useful material when your application doesn’t reach melting temperatures of phase change materials. Graphite materials have high temperature resistance, so they can be used in applications at temperatures beyond 200°C. At extreme temperatures, beyond 200°C, placing graphite films in a vacuum environment should be considered. This will prevent oxidation of the carbon within the graphite films. graphite films to be used for EMI shielding up to the GHz range, with superior attenuation.
这些薄膜不可重复使用，因为压力会使石墨粘附在其接触的每个表面上。当由石墨垫连接的表面彼此去除时，石墨垫粘在表面上，但沿着垫的石墨烯的各个层剥离。
导热垫和薄膜的可重复使用性
由于一些垫子含有硅胶，它们类似于间隙填充热界面材料，如果将它们压缩超过某个点，它们会保持轻微压缩。幸运的是，大多数导热垫具有高硬度，并且需要很大的力来变形垫的形状和厚度。这使得导热垫成为理想的可重复使用的热界面材料。
当我们考虑可重用性时，电影更像是硬件。通常，如果热敏膜完好无损且没有折痕，则它可以像热硬件一样重复使用。如果薄膜有折痕，可能会产生不需要的气穴。
导热胶带
Thermal Tape is a common interface material. Thermal tapes are adhesive on one or both sides so can either stick to just one surface, or join two surfaces together. This is typically done with a pressure sensitive adhesive that you need to compress between surfaces to get the mechanical bond a thermal tape can provide. The biggest difference between thermal tapes and your everyday, run-of-the-mill double-sided tapes is that they are specially formulated using high thermal conductivity fillers and polymers. There are thermal tapes that are just an adhesive. They’re placed on a liner or carrier to keep them in a sheet or roll before they make they’re way to their application. These baseless thermal tapes can be tricky to manipulate and apply correctly if not cut and handled properly. If any part of the thermal tape starts sticking to something, it can be difficult to remove the tape without stretching the adhesive. This is why a good portion of thermal tapes have a base material. These carriers are usually a thermally conductive film with the adhesive applied to one or both sides.不用担心那个失去螺丝
导热胶带可以减少对小型设备和散热器的安装硬件的需求，这些设备和散热器通常安装在一起。如果您在设计和旋转电路板后发现电路板上的小型设备需要一些热管理，这将特别有用。您可能没有空间安装硬件，但您仍然可以用一些热胶带将散热器贴在设备上。世界的重量
如果您有重型应用或尝试应用于表面的散热器，您可能需要重新考虑为您的应用使用导热胶带。较大散热器的重量可能会压倒导热胶带的机械强度。高水平的振动或冲击也可能压倒导热胶带的粘合力。虽然导热胶带具有一定程度的机械强度，并且在紧要关头表现良好，但它们通常不是粗糙应用的最佳热界面选择。坚持使用热敏胶带进行较小的应用。我被困在你身上
如果热敏胶带正在工作，则不可重复使用。他们想坚持你坚持他们的东西，不让他们走。有一些技巧，例如加热粘合剂，然后尝试将表面拉开以用热胶带拆卸组件。或者某些粘合剂需要某种溶剂或清洁剂来帮助去除表面上的任何残留物，这会破坏胶带的粘合能力。将导热胶带从其应用表面上剥离通常会使它们不均匀且作为未来应用的热界面材料无效。表面需要清洁，需要贴上新胶带。但是导热胶带相当容易应用，因此不一定排除需要返工或维护的应用使用导热胶带。
绝缘五金
硬件形式的热界面材料通常用于其高导热性和电绝缘性能。一些硬件也用作衬套或轴承表面。与其他 TIM 相比，热界面绝缘硬件以机械稳定性和更高的耐温性而闻名。绝缘五金材料
通常使用导热陶瓷，如氧化铝、氮化铝和氧化铍，因为它们价格实惠且相对容易制造成分立式硬件组件。云母是一种天然存在的矿物，具有片状结构，通过片状平面具有出色的导电性。由于云母广泛可用且易于加工，因此在电绝缘但导热的硬件组件方面也是一种流行的材料选择。硬件也可以由尼龙、PTFE 填充聚甲醛或邻苯二甲酸二烯丙酯等塑料制成。用于绝缘硬件的塑料需要高介电强度，以及良好的热稳定性和化学稳定性。
修改和定制不灵活
硬件需要以要使用的形状制造，尤其是陶瓷 TIM 硬件。大多数硬件都是特定于设备的，或者是为了适应非常特定的尺寸而创建的。The ceramics need to shaped for the device it will be used for and include proper lead and mounting holes before it’s fired. Otherwise, post machining would be required. Machining ceramics can be difficult and potentially hazardous. Ceramics are brittle and require delicate handling when machining and in the case of beryllium oxide, special precautions must be utilized to protect against inhalation of any particulates. Small particles of beryllium oxide are toxic when inhaled into the lungs. So all in all, it’s much easier to make ceramics the shape you need right from the get go and not after.
Plastics are a little more forgiving than ceramics when it comes to machining. Since most of these pieces are injection molded or extruded and cut to length, post processing typically isn’t required. But you may have an application that needs something a little different. In these cases, it tends to be easier to fabricate plastic insulating hardware in the final shape required since machining plastic can come with its own complications. Most machining processes heat up the plastic and cause unwanted deformation and warping. Some plastics can catch fire. Others may be too brittle and snap. In general, it’s best to get the shape you need for your plastic insulating hardware right when you purchase them.
与他人相处融洽
由于大多数硬件的弹性或可压缩性很小，因此它们与其他热界面材料结合使用。在表面不是非常光滑的情况下，可以使用更顺应的材料与绝缘硬件一起使用，以消除表面之间的气隙。导热硅脂可能不具有特定应用所需的电气隔离级别，将放置在硬件的两侧，以最大程度地减少任何气隙。这为应用提供了高导热性和表面之间的高电气隔离。在某些情况下，间隙垫或间隙填充器等材料应与硬件一起使用，尤其是在应用可能存在冲击和振动问题的情况下。在这些情况下，绝缘硬件热接口材料最好与另一种热接口材料类型一起使用。可重复使用的硬件
硬件，只要没有损坏，就可以像任何其他硬件一样重复使用。只需小心地从一个应用程序中取出，然后将硬件安装到新的组件中即可。但是，如果您将硬件与润滑脂等其他热界面材料结合使用，则需要清除润滑脂并更换以用于硬件的新应用。相变材料
相变材料是一种有趣的热界面材料类型。它由具有特定熔化温度的蜡物质组成，通常在 50-65°C 之间。 当材料从固体转变为液体时，材料的温度始终保持在其熔化温度，因为它会吸收热量。这为表面之间的温度控制提供了出色的效果。一旦相变材料吸收了其熔化潜热，即完全熔化固体所需的能量，那么相变材料将在液态下开始升高温度。
Many phase change materials are deposited onto a highly thermally conductive base material that is also installed in the application. Some use a thermal film or aluminum foil to hold the material before and while it’s installed. Other phase change materials have films on both sides so as you install the waxy material, the films from both sides are removed, leaving just the phase change material between the surfaces.
渗透到每一个角落和缝隙
当相变材料被加热到特定温度以上时，它会熔化并流入它之间的表面之间的任何现有角落和缝隙中。相变热界面材料甚至可以去除最微小的气穴，并在表面之间提供非常低的界面电阻。因此，在相变第一次熔化后，您可以指望在传递热量的表面之间始终保持低热阻。Mitigating Rough Patches
由于相变材料变成液体，它可以进入其他热界面材料无法完全进入的一些狭小空间。这也意味着它可以轻松处理更粗糙的表面。有瑕疵、粗糙斑点或任何不完美的表面都可以从使用相变材料进行传热中受益。不过，间隙填充物仍然是巨大身高差异的最佳选择。需要添加大量的相变材料，以占用与间隙填料相同的体积。必须爱泉
与导热硅脂一样，相变材料在首次应用于表面之间后会变薄。随着蜡熔化并填充任何可用的空隙，该材料现在是表面缺陷，不再增加材料的厚度。这就是为什么相变材料应与弹簧加载安装方法一起使用的原因。弹簧力将在相变材料处于液态时对其进行压缩。该力有助于使材料变薄，从而降低界面电阻。所有这些都有助于改善表面之间的热传递。
更换相变材料时易于清理
像导热硅脂一样，相变材料是不可重复使用的，但也不会像油脂那样一团糟地清理掉。与润滑脂不同，相变材料在冷却时会恢复为更坚固的形式，从而更容易刮掉表面。异丙醇等典型清洁液也可用于清洁蜡状相变材料，而无需对表面进行其他处理。
热环氧树脂
热环氧树脂是最坚固的热界面材料。热环氧树脂与其他环氧树脂的不同之处在于与树脂混合的导热填料。一些环氧树脂使用导热陶瓷颗粒，而另一些则使用小金属颗粒。像其他环氧树脂一样，有一部分和两部分树脂可以混合并应用于将表面连接在一起。使用的环氧树脂类型通常取决于连接在一起的材料。
具有多种材料的强度
环氧树脂可以做大多数其他热界面材料所没有的事情;热环氧树脂在其固化的表面之间产生牢固的机械粘合。这使得热环氧树脂既可以作为热界面材料，也可以作为安装方法。在某些情况下，这有助于减少产品或应用中使用的安装硬件数量。这就是为什么我们可以用环氧树脂制造散热器，我们称之为环氧树脂粘合散热器。
潜在的运输限制
热环氧树脂不可重复使用。像任何其他环氧树脂一样，一旦设置热环氧树脂，形成并附着在表面上的聚合物键就不会轻易断裂。这就是为什么在确定热环氧树脂适合您之前，您应该考虑可能需要对产品进行返工的原因。如果您需要对具有环氧树脂表面的设备进行维护，您将很难绕过散热器，甚至更难将其移除。
虽然市场上有溶剂可以去除特定的固化树脂，但它们是实验室或车间通常不会有的专用产品。有时你只需要把你的环氧树脂粘合带到节目中，然后看到或铣掉你一起环氧树脂的东西。当你在环氧树脂键的一侧有一个精致的电路板时，这当然是不可取的。
在环氧树脂固化之前，您确实有一些回旋余地来重新定向和重新安装环氧树脂粘结表面。这个时间取决于所用环氧树脂的温度、湿度和固化时间。如果您需要重做某些事情，清理未固化的环氧树脂通常更容易，因此您需要在混合环氧树脂之前确定自己在做什么，并在环氧树脂开始固化时确定。
具有多种材料的强度
构成热环氧树脂的树脂和固化剂中可能含有一些相当挥发性的化学物质。这就是为什么在运输未固化的环氧树脂时可能会有一些运输限制。未固化的热环氧树脂可能需要陆运，因为空运可能会带来空运公司不想管理的风险。
Next Steps: Reach Out to Boyd for Help in Selecting Your Interface Material
Contact Boyd to discuss your application and assess the thermal interface material options best suited for you.
