![]() It's super frustrating to wreck boards, even though I have learned a good amount. OK, I will get new paste and try no lead again, but I'll also get lead for a backup. I could probably shim better, but I think I'll get some glue for the heavier components. I've read it would probably be fine, but still can't being nervous about it. I have a low temp solder, but I'm hesitant to use it on PCBs that I hope will be in service for many years. With no lead on one side and lead on the other, the no lead would melt at ~217C if I let the lead profile run to the end (235C). I had a heavier component (optocoupler) on the bottom side almost fall off when baking the top. Your tip with the dot of paste is nice, I'll try that, thanks! I had hoped to just pop in a board and walk away, but I think I'll have to watch every board and stop the oven manually. Here it is without cleaning and on top of the overcooked board, though the color difference is more noticeable in person: I used this for a different, smaller board but watched for when the solder melted (should be ~183C), which was near the start of ramping to 235C. ramp to 235C and hold that for 60 seconds.Also I baked another with the same profile and some unpopulated pads have what I assume is burnt flux: The red color of the PCB got quite dark, which didn't happen other times when the solder melted. RF, PLC, CAD, HW Startups, Robotics, Microcomputing, DIY Audio, DIY Gear, DIY, Mindstorms, ASM, EE Books, Product Design, LabVIEW, Breadboard, RTLSDR, Manufacturing, Electronic Circuits.įor leaded maybe I heated it too much, not too little. AskElectronics, Electronics, ECE, RPi, NiceChips, DevKit, Arduino, micro:bit, Nucleo, STM32F4, MSP430, PSoC, ARM, Amp Hour, FPGA, DSP,.How to solder: SMD Resistors, SMD ICs, SMD QFP IC, SMD Drag Solder, SMD Tips, 1980 Soldering Videos.Gerbv, GerberLogix, DFM Now, ViewMate, ZofzPCB, GC-Prevue. Pro ($$$$): Altium, Allegro, OrCAD, PADS, Xpedition. WIKI / FAQ / PCB Review Tips / 3D models / SPICE models / Book ListĮagle, Fritzing, Horizon, KiCad, LibrePCB, ( Comparison).Links within /r/PrintedCircuitBoard subreddit: This subreddit isn't meant for repairing PCBs. Cut back the time above liquidus (TAL) to 40–60 seconds.Official Printed Circuit Board Subreddit - schematic capture / PCB layout / gerber / review / electronics assembly / circuit simulation.Utilize a peak temperature ranging from 235°-240 ☌.Adjust the belt speed to decrease the total time in oven to a recommended ramp rate of 1 ☌/second from ambient to peak.Opt for a ramp to peak profile, as opposed to a soak profile.There are also steps to take when setting up one's reflow profile to reduce the amount of heat exposure to the solder paste during the reflow process and prevent graping: This pairing means that graping can be resolved as it occurs, which is ideal for miniaturization processes. Future solder paste flux formulations provide sufficient activity paired with re-oxidation mitigation capabilities. These solder powder characteristics help to eliminate the graping phenomenon. This barrier not only improves the paste release from the stencil, but also provides an ideal surface area-to-volume ratio. Solder powders are available that provide a tighter distribution range as well as a high oxidation barrier. This amount only refers to solder paste, so the actual amount will be higher because of the other evaporated materials. With a flux amount of 10.5, this equals about 300 grams flux in the cooling area every month. The graping phenomenon can be resolved utilizing proper solder materials in addition to correct reflow profile settings. The average solder paste consumption on this line is 3 kilograms per day. Finer particle sizes places added pressure on the solder paste flux to remove surface oxides, which leaves the outside of the joint not fully coalesced, producing the irregular surface finish known as graping. While solder paste can be manufactured using any size range, there has been a move towards finer particle sizes, especially for fine feature stencil printing. The increased surface oxidation is the result of smaller printed paste deposit volumes that cause a diminished surface area to flux ratio of the solder particle, resulting in flux exhaustion. Graping is also caused by increased surface oxidation. ![]() Lead-free reflow soldering temperatures are higher, which results in more graping. The viscosity of the flux decreases as the temperature of the reflow oven increases. Graping occurrence has continued to increase since it was first identified in 2006. The solder that is partially coalesced resembles a cluster of grapes, hence the derivation of the phenomenon’s name. Graping is a phenomenon marked by the appearance of unreflowed solder particles on top of the solder mass. Phenomenon occurring to unreflowed solder. ![]()
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