LinqSil LSC200 liquid silicone junction coating resin

P‑N junction coating resins for diode assembly

Updat­ed Novem­ber 2016: CAPLINQ has devel­oped its own brand of Junc­tion Coat­ing Resin Sil­i­cones for thyris­tors and oth­er appli­ca­tions that require P‑N junc­tion coat­ing resins. LCS-100 is our alter­na­tive to the Shin-Etsu KJR-9060AWE.

Recent­ly, a cus­tomer using Shin-Etsu KJR-4013E, the indus­try-stan­dard for p‑n junc­tion coat­ing resins, asked if they could use the KJR-4013E at tem­per­a­tures of 500C for 10 min­utes. This because this was the sol­der pro­file used for sol­der reflow.

P-N Junction Coating Resin TGA
TGA Graph Junc­tion Coat­ing Silicone

KJR-4013E is a flex­i­ble, mois­ture-cure sil­i­cone most often used as p‑n junc­tion-coat­ing resins in the man­u­fac­ture of diodes. Ask us for the Tech­ni­cal Data Sheet (TDS) for Shin-Etsu KJR-4013. The KJR-4013E is a sil­i­cone mate­r­i­al and as such can with­stand high­er tem­per­a­tures. 500C is indeed a very high tem­per­a­ture, and it will def­i­nite­ly not sur­vive long times at this tem­per­a­ture. The point and the ques­tion how­ev­er is if it will sur­vive a short expo­sure time of 10 min­utes at that temperature.

An approx­i­mate degra­da­tion tem­per­a­ture for the KJR-4013E is around 300C after which it degrades quick­ly in time. If the mate­r­i­al is not degrad­ed, then it should still be able to pro­tect the P‑N junc­tion. A good way to test for this would be, use a ther­mo­cou­ple in the oven to mea­sure the exact time and tem­per­a­ture expo­sure of the mate­r­i­al dur­ing your sol­der­ing process and then to run a ther­mo­gravi­met­ric analy­sis (TGA) on the sil­i­cone for this same time/temperature profile.

As shown in the graph (Note: this is NOT the graph for KJR-4013E), once a mate­r­i­al goes beyond a cer­tain point, it begins to degrade quick­ly, and the process is irre­versible. The point at which the degra­da­tion accel­er­ates is dif­fer­ent for dif­fer­ent mate­ri­als, but for non-sol­vent con­tain­ing sil­i­cones, this can be as lit­tle as 3–4% of weight loss. Keep in mind with this graph that the tem­per­a­ture ramp is 10C per minute (as shown in the Method), and so the total time to gen­er­ate THIS graph up to 450C was 45 min­utes. This will NOT be the case with a 10 minute sol­der process, even as it ramps up to 500C, but a ther­mo­cou­ple through the oven will tell this sto­ry much more accurately.

Please vis­it our web­site for more infor­ma­tion about junc­tion coat­ing resin sil­i­cones, our sil­i­cones for LED encap­su­la­tion or any oth­er of our spe­cial­ty sil­i­cone prod­ucts. You can also con­tact us for more infor­ma­tion on P‑N junc­tion coat­ing resin silicones.

About Chris Perabo

Chris is an energetic and enthusiastic engineer and entrepreneur. He is always interested in taking highly technical subjects and distilling these to their essence so that even the layman can understand. He loves to get into the technical details of an issue and then understand how it can be useful for specific customers and applications. Chris is currently the Director of Business Development at CAPLINQ.

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