Problem with date in Yii2

I have a very annoying problem with yii2. I am able to do the insertion until 12/12 of the year that I want, but when I put the day above 13 it locks as empty and inserts in the bank the value 1970-01-01. I'll put the codes in the form, the model and the controller.

Controller

public function actionUpdate($id)
{
    $model = $this->findModel($id);
    if(Yii::$app->request->isAjax && $model->load($_POST))
    {
        Yii::$app->response->format = 'json';
        return \yii\widgets\ActiveForm::validate($model);
    } 
    if ($model->load(Yii::$app->request->post())) {
        $model->data_nascimento = date("Y-m-d", strtotime($model->data_nascimento));

        $data = $model->data_nascimento;
        var_dump($data);
        $delet = $model->niver_deleted;
        if ($delet == 0){
            $delet = 'false';
        }
        else{
            $delet = 'true';
        }

         $ano = substr($data, 0, 4);
         $mes =  substr($data, -2);
         $dia = substr($data, 5, 2);
         $query = Yii::$app->db2->createCommand("update funcionario set data_nascimento = '{$ano}-{$mes}-{$dia}', niver_deleted = {$delet} where id = '$id'")->queryAll();
        debug_print_backtrace();
        return $this->redirect(['view', 'id' => $model->id]);
    }
    $model->data_nascimento = Yii::$app->getFormatter()->asDate($model->data_nascimento);
    var_dump($model->data_nascimento);
    return $this->render('update', [
        'model' => $model,
    ]);
}

Form

        <?= $form->field($model, 'data_nascimento')->widget(DatePicker::className(), [
            'language' => 'pt-BR',
            'dateFormat' => 'php:d/m/Y',
            'options' => ['class' => 'form-control'],
        ])->textInput(['maxlength' => 10, 'placeholder' => "__/__/____"])   ?> 
    <?= $form->field($model, 'niver_deleted')->dropDownList(['1' => 'Sim', '0' => 'Não'],['prompt'=>'Selecione uma opção']) ?>
</div>
<div class="box-footer">
    <?= Html::submitButton(Yii::t('app', 'Salvar'), ['class' => 'btn btn-success btn-flat']) ?>
    <?= Html::a(Yii::t('app', 'Voltar'), ['index'], ['class' => 'btn btn-danger btn-flat']) ?>
</div>
<?php ActiveForm::end(); ?>
</div>
<script>
  jQuery(function($) {
    $("#aniversario-data_nascimento").mask("99/99/9999");
});
</script>

Model

 public function validateData($attribute, $params)
{
    $date = date('d/m/Y');
    if (strtotime($date) < strtotime($this->$attribute))
        $this->addError($attribute, 'Data não pode ser superior à hoje.');
}

/**
 * {@inheritdoc}
 */
public function rules()
{
    return [
        [['codigo', 'nome'], 'required'],
        [['data_nascimento'], 'safe'],
        [['niver_deleted'], 'boolean'],
        ['data_nascimento', 'date', 'format' => 'php:d/m/Y', 'message' => 'Data inválida.'],
        [['nome'], 'string', 'max' => 80],
        ['data_nascimento', 'validateData'],
    ];
}