Everyone knows how to prevent BPA bending and board warping from going through the reflow furnace. The following is an explanation for everyone:

1. Reduce the influence of temperature on PCB board stress

Memandangkan “suhu” adalah sumber utama tegasan papan, selagi suhu ketuhar aliran semula diturunkan atau kadar pemanasan dan penyejukan papan dalam ketuhar aliran semula diperlahankan, kejadian lenturan dan lenturan plat boleh menjadi sangat ketara. dikurangkan. Walau bagaimanapun, kesan sampingan lain mungkin berlaku, seperti litar pintas pateri.

2. Menggunakan kepingan Tg tinggi

Tg ialah suhu peralihan kaca, iaitu suhu di mana bahan berubah daripada keadaan kaca kepada keadaan getah. Semakin rendah nilai Tg bahan, semakin cepat papan mula lembut selepas memasuki ketuhar aliran semula, dan masa yang diperlukan untuk menjadi keadaan getah lembut Ia juga akan menjadi lebih lama, dan ubah bentuk papan sudah tentu akan menjadi lebih serius . Menggunakan plat Tg yang lebih tinggi boleh meningkatkan keupayaannya untuk menahan tekanan dan ubah bentuk, tetapi harga bahannya agak tinggi.

3. Tingkatkan ketebalan papan litar

In order to achieve the purpose of lighter and thinner for many electronic products, the thickness of the board has left 1.0mm, 0.8mm, and even a thickness of 0.6mm. It is really difficult for such a thickness to keep the board from deforming after the reflow furnace. It is recommended that if there is no requirement for lightness and thinness, the board* can use a thickness of 1.6mm, which can greatly reduce the risk of bending and deformation of the board.

4. Reduce the size of the circuit board and reduce the number of puzzles

Since most of the reflow furnaces use chains to drive the circuit board forward, the larger the size of the circuit board will be due to its own weight, dent and deformation in the reflow furnace, so try to put the long side of the circuit board as the edge of the board. On the chain of the reflow furnace, the depression and deformation caused by the weight of the circuit board can be reduced. The reduction in the number of panels is also based on this reason. Low dent deformation.

5. Lekapan dulang relau terpakai

If the above methods are difficult to achieve, *reflow carrier/template is used to reduce the amount of deformation. The reason why the reflow carrier/template can reduce the bending of the plate is because it is hoped whether it is thermal expansion or cold contraction. The tray can hold the circuit board and wait until the temperature of the circuit board is lower than the Tg value and start to harden again, and can also maintain the size of the garden.

Jika palet satu lapisan tidak dapat mengurangkan ubah bentuk papan litar, penutup mesti ditambah untuk mengapit papan litar dengan palet atas dan bawah. Ini boleh mengurangkan masalah ubah bentuk papan litar melalui relau aliran semula. Walau bagaimanapun, dulang ketuhar ini agak mahal, dan ia perlu diletakkan secara manual dan dikitar semula.

6. Gunakan Penghala bukannya V-Cut untuk menggunakan sub-board
Memandangkan V-Cut akan memusnahkan kekuatan struktur panel antara papan litar, cuba jangan gunakan sub-board V-Cut atau kurangkan kedalaman V-Cut.