上季度陪一家连接器厂开新品评审会，议题是 0.635mm 间距的板端连接器用啥料。会上三个方案摆着：PA9T、PA6T、还有便宜一档的 PA46。研发说都行，采购说差价三成呢，品质说去年那个用 PA46 的批次针脚间距漂了……
会议开成一个半小时，最后拍板用的 PA9T——理由不是谁说服了谁，是有人把三家的长期耐温曲线和吸湿后尺寸变化摆到了同一张表上，数字替大家做了决定。
那场会留给我的印象很深：高温尼龙选型的正确打开方式，是不比名气、比三个硬指标——长期使用温度、回流焊耐受力、吸湿后的尺寸稳定。下面这些，是科隆新材参与连接器评审时反复用到的那张表的底稿。
一、PA9T 凭什么当尺寸之王
PA9T 的碳链更长（壬二胺 + 对苯二甲酸），这带来两个结果：
①吸水率降到 2-3%，是高温尼龙里最低的。长期尺寸稳定性最好——这是它能做精密连接器的根本原因。针脚间距在长期使用中不能漂移的件，PA9T 是答案。
②单体成本高、全球供应集中。这就是 PA9T 价格最高的原因，不是配方贵，是原料贵。
二、价格之王的账
PA9T 的适用判断很简单：当“高温”和“高精度”必须同时满足时，PA9T 基本没得替代。
反过来——如果精度要求不高，用 PA9T 是浪费。它的溢价只在尺寸稳定性上，其他地方并不比 PA6T 强。宁波科隆给客户算 PA9T 的账，就一句话：你为“尺寸不漂移”付的钱，值不值，由公差决定。
三、三个硬指标看 PA9T
指标一：回流焊温度。只要是无铅回流焊，直接跳到高温尼龙，没有第二条路。
指标二：壁厚与充填。现在的连接器越做越薄，0.3mm 甚至更薄很常见。极薄壁 + 高温 → 需要最高等级流动性的高流动级 PA9T。
指标三：精度要求（这一条决定要不要上 PA9T）。公差 ≥±0.1mm → PA6T 够用；公差 ±0.05mm 以内且长期稳定 → PA9T。间距越密，越没得商量。
四、加工铁律
模温必须 120-140℃，这一条没有商量余地。模温不够，结晶不完全：件脆、表面差、耐热缩水。配套模具：模温 130℃ 以上，普通模具的冷却水路和密封件可能扛不住，需要专门设计；高温料对模具磨损更大，建议硬化处理；热流道系统要选高温型。料温按牌号规格书走，别抄 PA66 的参数表。
五、长期可靠性：CAF
高温尼龙在高湿 + 高压 + 长期通电的环境下，存在电化学迁移（CAF）风险——这是连接器类产品的长期可靠性课题。选材时不能只看初始 CTI，还要看长期绝缘可靠性。科隆公司验精密连接器料，CAF 是长测项，这一项不过，前面性能再好也白搭。
六、最常见的坑
坑 1：拿 PA9T 做不需要精密的件。PA9T 的溢价全在尺寸稳定性上，精度不需要的件用 PA9T，是纯浪费——科隆新材见过最可惜的浪费，就是普通继电器底座用 PA9T，性能用不上，钱白付。
坑 2：以为 PA9T 是 PA6T 的全面升级。不是。它强在尺寸稳定和耐热，韧性、加工性不一定占优。按件选，不按名气选。
坑 3：忽略 CAF。只看初始 CTI，不看长期通电高湿环境下的电化学迁移，精密件会在质保期外开始失效。
坑 4：间距需求判断失误。0.35-0.5mm 间距的板对板连接器，PA46 直接被排除，PA6T 也悬——这一档就是 PA9T 的活。
坑 5：只看单价不看全生命周期。PA9T 单价高，但连接器接触不良的返修成本是料价的几十倍，尺寸稳定直接压这个风险。
边界声明：LED 支架、传感器外壳这类“高温但不极精密”的件，PA6T/PA10T 就够，别为用不上的精度付 PA9T 的溢价。判断标准就一条：针脚间距在长期使用中会不会漂移。会漂 → PA9T；不会 → PA6T/PA10T。
Last quarter, I accompanied a connector factory to a new product review meeting, and the topic was what materials to use for a 0.635mm pitch board-end connector. At the meeting, three options were presented: PA9T, PA6T, and the cheaper PA46. R&D said anything was fine, but procurement said the price difference was 30%, and the quality was that last year's batch with PA46 had a pin pitch that drifted......
The meeting lasted an hour and a half, and in the end, we decided on the PA9T—the reason wasn't that anyone convinced anyone, but someone put the long-term temperature resistance curves and dimensional changes after moisture absorption from all three companies on the same table, and the numbers made the decision for everyone.
That session left a deep impression on me: the correct way to select high-temperature nylon is not to compare reputation, but to compare three hard criteria—long-term use temperature, reflow soldering resistance, and dimensional stability after moisture absorption. The following are the drafts of the table repeatedly used by Kolon New Materials during connector evaluations.
1. Why is PA9T considered the king of sizes
PA9T its carbon chain is longer (nonenediamine + terephthalic acid), which leads to two results:
(1) Water absorption rate drops to 2-3%, the lowest among high-temperature nylons. Long-term dimensional stability is the best — this is the fundamental reason it can make precision connectors. For components where pin pitch cannot drift during long-term use, PA9T is the answer.
(2) High unit cost and global supply is concentrated. That's why PA9T is the most expensive—not because the formula is expensive, but because the raw materials are expensive.
2. The price king's
PA9T is easy to judge: when both "high temperature" and "high precision" must be met, PA9T is basically irreplaceable.
Conversely—if precision isn't required, using PA9T is wasteful. Its premium is only in dimensional stability; otherwise, it's not better than PA6T. Ningbo Cologne's calculations for customers on PA9T sum it up in one sentence: whether you pay for "dimensional stability" is worth it depends on tolerances.
Three, three hard metrics to look at PA9T .
Indicator One: Reflow soldering temperature. As long as it's lead-free reflow soldering, jump straight to high-temperature nylon—there's no other way.
Indicator Two: Wall thickness and filling. Nowadays, connectors are getting thinner, with 0.3mm or even thinner being common. Ultra-thin walls + high temperature → requires the highest flow level of high-flow PA9T.
Indicator Three: Precision requirements (this one determines whether to use PA9T). Tolerance ≥±0.1mm→ PA6T is sufficient; Tolerance ± within 0.05mm and stable over the long term → PA9T. The tighter the spacing, the less negotiable.
4. Iron Rules of Processing
Mold temperature must be 120-140°C, this rule is non-negotiable. Insufficient mold temperature, incomplete crystallization: brittle, poor surface, resistant to heat shrinkage. Matching mold: Mold temperature above 130°C, ordinary mold cooling water channels and seals may not withstand and require special design; High-temperature material causes greater wear on molds, so hardening treatment is recommended; Hot runner system should be high-temperature type. Material temperature should follow the grade specification manual; do not copy the PA66 parameter table.
5. Long-term reliability: CAF
High-temperature nylon carries electrochemical migration (CAF) risks under high humidity + high voltage + long-term power supply—this is a long-term reliability issue for connector products. When selecting materials, you shouldn't just look at the initial CTI; long-term insulation reliability must also be considered. Cologne tests precision connector materials, and CAF is a long-term test. However, no matter how good the previous performance is, it's useless.
6. Most common pitfalls
Pitfall 1: Using PA9T to make parts that don't require precision. The premium of PA9T is all about dimensional stability; using PA9T for parts that don't require precision is pure waste—the most regrettable waste I've seen from Cologne New Materials is using PA9T for ordinary relay bases, which don't perform well and cost nothing.
Pitfall 2: Thought PA9T was a comprehensive upgrade of PA6T. No. Its strength lies in dimensional stability and heat resistance; toughness and processability may not be better. Choose by part, not by reputation.
Pitfall 3: Ignore CAF. Only look at initial CTI, ignore electrochemical migration in long-term energized and high-humidity environments; precision parts will start to fail outside the warranty period.
Pitfall 4: Misjudgment of spacing requirements. For board-to-board connectors with a 0.35-0.5mm pitch, PA46 is completely excluded, and PA6T is also in trouble—this is where PA9T really shines.
Pitfall 5: Only look at unit price, not the full lifecycle. PA9T is expensive, but the cost of reworking connector poor contact is dozens of times higher than material price, and stable size directly offsets this risk.
Boundary Statement: For "high-temperature but not ultra-precise" parts like LED brackets and sensor housings, PA6T/PA10T are sufficient; don't pay a premium for PA9T for unused precision. The only criterion for judgment is whether pin pitch drifts over long-term use. It will drift → PA9T; No, → PA6T/PA10T
