I have recently conducted some research on binding SMD components with glass and ceramic substrates using pure indium and indium alloys. The results are very satisfactory, and the technique may find some applications in HV and high power density solutions. One can directly solder a MOSFET to a ceramic heatsink or a string of HV resistors to an insulating glass plate without prior metalisation. The only thing to improve is the initial wettability. Do you happen to know of any tips regarding the composition of the alloy or the preparation of the substrate? Will indium bind to AlN? I have no sample to perform a test. Best regards, Piotr
Soldering to glass
Started by ●April 19, 2020
Reply by ●April 19, 20202020-04-19
Piotr Wyderski wrote...> > I have recently conducted some research on binding SMD components > with glass and ceramic substrates using pure indium and indium > alloys. The results are very satisfactory, and the technique may > find some applications in HV and high power density solutions. > One can directly solder a MOSFET to a ceramic heatsink or a > string of HV resistors to an insulating glass plate without > prior metalisation. > > The only thing to improve is the initial wettability. Do you > happen to know of any tips regarding the composition of the > alloy or the preparation of the substrate? > > Will indium bind to AlN? I have no sample to perform a test.Soldering HV components to a ceramic heatsink with indium is a fascinating idea. For those who often run things hot, its low 150C limit may be an issue, but alloys may be in order. -- Thanks, - Win
Reply by ●April 19, 20202020-04-19
On 2020-04-19 07:16, Winfield Hill wrote:> Piotr Wyderski wrote... >> >> I have recently conducted some research on binding SMD components >> with glass and ceramic substrates using pure indium and indium >> alloys. The results are very satisfactory, and the technique may >> find some applications in HV and high power density solutions. >> One can directly solder a MOSFET to a ceramic heatsink or a >> string of HV resistors to an insulating glass plate without >> prior metalisation. >> >> The only thing to improve is the initial wettability. Do you >> happen to know of any tips regarding the composition of the >> alloy or the preparation of the substrate? >> >> Will indium bind to AlN? I have no sample to perform a test. > > Soldering HV components to a ceramic heatsink with indium is > a fascinating idea. For those who often run things hot, its > low 150C limit may be an issue, but alloys may be in order.You can indium-solder to glass and ceramics. It's much easier if you have an ultrasonic soldering iron. Those cost kilobucks unfortunately, but they sure are fun. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 19, 20202020-04-19
On Sunday, 19 April 2020 16:59:13 UTC+1, Phil Hobbs wrote:> On 2020-04-19 07:16, Winfield Hill wrote: > > Piotr Wyderski wrote... > >> > >> I have recently conducted some research on binding SMD components > >> with glass and ceramic substrates using pure indium and indium > >> alloys. The results are very satisfactory, and the technique may > >> find some applications in HV and high power density solutions. > >> One can directly solder a MOSFET to a ceramic heatsink or a > >> string of HV resistors to an insulating glass plate without > >> prior metalisation. > >> > >> The only thing to improve is the initial wettability. Do you > >> happen to know of any tips regarding the composition of the > >> alloy or the preparation of the substrate? > >> > >> Will indium bind to AlN? I have no sample to perform a test. > > > > Soldering HV components to a ceramic heatsink with indium is > > a fascinating idea. For those who often run things hot, its > > low 150C limit may be an issue, but alloys may be in order. > > You can indium-solder to glass and ceramics. It's much easier if you > have an ultrasonic soldering iron. Those cost kilobucks unfortunately, > but they sure are fun.Another approach (which I have used) is to fire a patch of silver or silver/palladium thick film ink onto an alumina substrate and then solder onto that metallic coating. John
Reply by ●April 19, 20202020-04-19
On 19 Apr 2020 04:16:05 -0700, Winfield Hill <winfieldhill@yahoo.com> wrote:>Piotr Wyderski wrote... >> >> I have recently conducted some research on binding SMD components >> with glass and ceramic substrates using pure indium and indium >> alloys. The results are very satisfactory, and the technique may >> find some applications in HV and high power density solutions. >> One can directly solder a MOSFET to a ceramic heatsink or a >> string of HV resistors to an insulating glass plate without >> prior metalisation. >> >> The only thing to improve is the initial wettability. Do you >> happen to know of any tips regarding the composition of the >> alloy or the preparation of the substrate? >> >> Will indium bind to AlN? I have no sample to perform a test. > > Soldering HV components to a ceramic heatsink with indium is > a fascinating idea. For those who often run things hot, its > low 150C limit may be an issue, but alloys may be in order.Seems to me that epoxy would work as well, maybe better. If the parts are flat, epoxy with some compression would flow out to make a very thin layer. The glass or ceramic may well dominate theta anyhow. DPAK thick-film resistors are great for heatsinking. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●April 19, 20202020-04-19
On 2020-04-19 12:34, jrwalliker@gmail.com wrote:> On Sunday, 19 April 2020 16:59:13 UTC+1, Phil Hobbs wrote: >> On 2020-04-19 07:16, Winfield Hill wrote: >>> Piotr Wyderski wrote... >>>> >>>> I have recently conducted some research on binding SMD components >>>> with glass and ceramic substrates using pure indium and indium >>>> alloys. The results are very satisfactory, and the technique may >>>> find some applications in HV and high power density solutions. >>>> One can directly solder a MOSFET to a ceramic heatsink or a >>>> string of HV resistors to an insulating glass plate without >>>> prior metalisation. >>>> >>>> The only thing to improve is the initial wettability. Do you >>>> happen to know of any tips regarding the composition of the >>>> alloy or the preparation of the substrate? >>>> >>>> Will indium bind to AlN? I have no sample to perform a test. >>> >>> Soldering HV components to a ceramic heatsink with indium is >>> a fascinating idea. For those who often run things hot, its >>> low 150C limit may be an issue, but alloys may be in order. >> >> You can indium-solder to glass and ceramics. It's much easier if you >> have an ultrasonic soldering iron. Those cost kilobucks unfortunately, >> but they sure are fun. > > Another approach (which I have used) is to fire a patch of silver or > silver/palladium thick film ink onto an alumina substrate and then > solder onto that metallic coating. > > John >With what? I'd expect that to fall apart when you ablated the binder. The indium solder technique is hermetic, which helps in many cases. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 19, 20202020-04-19
On Sunday, April 19, 2020 at 4:16:16 AM UTC-7, Winfield Hill wrote:> Piotr Wyderski wrote... > > > > I have recently conducted some research on binding SMD components > > with glass and ceramic substrates using pure indium and indium > > alloys. The results are very satisfactory,> Soldering HV components to a ceramic heatsink with indium is > a fascinating idea. For those who often run things hot, its > low 150C limit may be an issue, but alloys may be in order.A possible concern, is that indium forms a transparent oxide that is conductive. How does one debug a HV circuit when conductive tracks on the board aren't carbonized, but... transparent and invisible?
Reply by ●April 19, 20202020-04-19
On Sunday, 19 April 2020 19:33:59 UTC+1, Phil Hobbs wrote:> On 2020-04-19 12:34, jrwalliker@gmail.com wrote:> > Another approach (which I have used) is to fire a patch of silver or > > silver/palladium thick film ink onto an alumina substrate and then > > solder onto that metallic coating.> With what? I'd expect that to fall apart when you ablated the binder. > > The indium solder technique is hermetic, which helps in many cases. >The thick-film inks are a blend of powdered glass and metal particles, so when the ink is fired the glass particles fuse to the glass binder in the alumina. (Most commercial alumina is made by sintering a mixture of alumina with a small percentage of glass.) The final result is a mostly metallic coating strongly bonded to the surface of the alumina. Tin/lead solder wets it nicely when the metal is silver or silver/palladium. The glass component means that it can be hermetic. I used this technique in an implantable medical application a long time ago. Indium is nice, but as already mentioned it is unsuitable for high temperatures. John
Reply by ●April 19, 20202020-04-19
On Sunday, 19 April 2020 19:45:05 UTC+1, whit3rd wrote:> On Sunday, April 19, 2020 at 4:16:16 AM UTC-7, Winfield Hill wrote: > > Piotr Wyderski wrote... > > > > > > I have recently conducted some research on binding SMD components > > > with glass and ceramic substrates using pure indium and indium > > > alloys. The results are very satisfactory, > > > Soldering HV components to a ceramic heatsink with indium is > > a fascinating idea. For those who often run things hot, its > > low 150C limit may be an issue, but alloys may be in order. > > A possible concern, is that indium forms a transparent oxide that is > conductive. How does one debug a HV circuit when conductive > tracks on the board aren't carbonized, but... transparent and > invisible?So does tin. John
Reply by ●April 19, 20202020-04-19
On 2020-04-19 14:45, whit3rd wrote:> On Sunday, April 19, 2020 at 4:16:16 AM UTC-7, Winfield Hill wrote: >> Piotr Wyderski wrote... >>> >>> I have recently conducted some research on binding SMD components >>> with glass and ceramic substrates using pure indium and indium >>> alloys. The results are very satisfactory, > >> Soldering HV components to a ceramic heatsink with indium is >> a fascinating idea. For those who often run things hot, its >> low 150C limit may be an issue, but alloys may be in order. > > A possible concern, is that indium forms a transparent oxide that is > conductive. How does one debug a HV circuit when conductive > tracks on the board aren't carbonized, but... transparent and > invisible? >The vapour pressure of indium is insignificant at soldering temperatures. It boils at around 2000 C. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
